US20160198976A1 - Locating features in the heart using radio frequency imaging - Google Patents
Locating features in the heart using radio frequency imaging Download PDFInfo
- Publication number
- US20160198976A1 US20160198976A1 US14/996,145 US201614996145A US2016198976A1 US 20160198976 A1 US20160198976 A1 US 20160198976A1 US 201614996145 A US201614996145 A US 201614996145A US 2016198976 A1 US2016198976 A1 US 2016198976A1
- Authority
- US
- United States
- Prior art keywords
- antenna
- feature
- signals
- patient
- waves
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/42—Details of probe positioning or probe attachment to the patient
- A61B8/4245—Details of probe positioning or probe attachment to the patient involving determining the position of the probe, e.g. with respect to an external reference frame or to the patient
- A61B8/4254—Details of probe positioning or probe attachment to the patient involving determining the position of the probe, e.g. with respect to an external reference frame or to the patient using sensors mounted on the probe
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/0507—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves using microwaves or terahertz waves
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
- A61B5/6813—Specially adapted to be attached to a specific body part
- A61B5/6823—Trunk, e.g., chest, back, abdomen, hip
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
- A61N1/365—Heart stimulators controlled by a physiological parameter, e.g. heart potential
- A61N1/36514—Heart stimulators controlled by a physiological parameter, e.g. heart potential controlled by a physiological quantity other than heart potential, e.g. blood pressure
- A61N1/36578—Heart stimulators controlled by a physiological parameter, e.g. heart potential controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by mechanical motion of the heart wall, e.g. measured by an accelerometer or microphone
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
- A61B2560/04—Constructional details of apparatus
- A61B2560/0406—Constructional details of apparatus specially shaped apparatus housings
- A61B2560/0412—Low-profile patch shaped housings
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/02—Details of sensors specially adapted for in-vivo measurements
- A61B2562/0209—Special features of electrodes classified in A61B5/24, A61B5/25, A61B5/283, A61B5/291, A61B5/296, A61B5/053
- A61B2562/0217—Electrolyte containing
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/14—Coupling media or elements to improve sensor contact with skin or tissue
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/16—Details of sensor housings or probes; Details of structural supports for sensors
- A61B2562/166—Details of sensor housings or probes; Details of structural supports for sensors the sensor is mounted on a specially adapted printed circuit board
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/06—Devices, other than using radiation, for detecting or locating foreign bodies ; determining position of probes within or on the body of the patient
- A61B5/061—Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/08—Detecting organic movements or changes, e.g. tumours, cysts, swellings
- A61B8/0833—Detecting organic movements or changes, e.g. tumours, cysts, swellings involving detecting or locating foreign bodies or organic structures
- A61B8/085—Detecting organic movements or changes, e.g. tumours, cysts, swellings involving detecting or locating foreign bodies or organic structures for locating body or organic structures, e.g. tumours, calculi, blood vessels, nodules
Definitions
- the present invention relates generally to methods and systems for medical diagnostic imaging, and specifically to radio frequency (RF)-based imaging.
- RF radio frequency
- Narrowing of the coronary arteries due to atherosclerosis is commonly treated by implantation of a stent, using a catheter, to hold the artery open.
- the treated artery closes up again due to in-stent restenosis, necessitating further treatment.
- Accurate assessment of such restenosis generally requires re-catheterization.
- a number of non-invasive techniques have been proposed, such as in U.S. Pat. No. 6,729,336, in which an electromagnetic wave transmitter is used to excite a stent, and an acoustic sensor detects stent acoustic oscillations.
- RF imaging is best known in the context of radar systems, but RF diagnostic imaging systems have also been developed for medical applications.
- U.S. Patent Application Publication 2008/0169961 whose disclosure is incorporated herein by reference, describes computerized tomography using radar, which may be used for generating an image of living tissue.
- U.S. Pat. No. 7,454,242 whose disclosure is incorporated herein by reference, describes tissue-sensing adaptive radar imaging for breast tumor detection.
- U.S. Pat. No. 6,061,589 whose disclosure is incorporated herein by reference, describes a microwave antenna for use in a system for detecting an incipient tumor in living tissue, such as that of a human breast, in accordance with differences in relative dielectric characteristics.
- a composite Maltese Cross or bow-tie antenna construction is employed to irradiate the living tissue and to collect backscatter or other scatter returns.
- Embodiments of the present invention that are described hereinbelow provide improved devices and methods for detecting features inside a living body using RF imaging techniques. Although some of these embodiments are directed specifically to detection of features in the heart, and specifically in the coronary arteries, the principles of these embodiments may similarly be applied in imaging, detection and tracking of features elsewhere in the body.
- diagnostic apparatus including an antenna, which is configured to direct radio frequency (RF) electromagnetic waves into a living body and to generate signals responsively to the waves that are scattered from within the body.
- Processing circuitry is configured to process the signals so as to locate a feature in a blood vessel in the body.
- RF radio frequency
- the apparatus includes an ultrasound transducer, and the processing circuitry is configured to guide the ultrasound transducer to direct an ultrasonic beam toward the feature.
- the feature located by the processing circuitry includes a stent, and the ultrasound transducer is configured to generate a Doppler signal responsively to a flow of blood through the stent.
- the apparatus includes a tracking unit, which is configured to track respective coordinates of the antenna and of the ultrasound transducer, and the processing circuitry is configured to guide the ultrasound transducer responsively to the respective coordinates.
- the apparatus typically includes position transducers fixed respectively to the ultrasound transducer and to the antenna, wherein the tracking unit is configured to track the respective coordinates responsively to position signals exchanged between the position transducers and the tracking system.
- the apparatus includes a display, wherein the processing circuitry is configured to guide the ultrasound transducer by driving the display to present to an operator of the ultrasound transducer an indication of a direction in which the ultrasound transducer should be aimed.
- the blood vessel is a coronary artery.
- the processing circuitry may be configured to track a cyclical motion of the feature over multiple cycles of the heart.
- the processing circuitry is configured to locate the feature responsively to a difference in a dielectric constant of the feature relative to surrounding tissue.
- diagnostic apparatus including an antenna, having a front surface configured to brought into contact with an outer surface of a living body so as to direct radio frequency (RF) electromagnetic waves into the body and to generate signals responsively to the waves that are scattered from within the body.
- RF radio frequency
- a dielectric gel is adapted to be spread between the outer surface of the body and the front surface of the antenna.
- Processing circuitry is configured to process the signals so as to locate a feature in the body.
- the body has a first dielectric constant
- the gel has a second dielectric constant that is chosen to match the first dielectric constant.
- the gel has a dielectric constant that is between 30 and 75.
- the gel may be adhesive.
- the gel is water-based and includes an additive selected from a group of additives consisting of an alcohol, a salt, a sugar, and glycerin.
- the gel includes silicone and an additive having a dielectric constant greater than 70.
- diagnostic apparatus including an antenna, which has a front surface and is configured to direct radio frequency (RF) electromagnetic waves from the front surface into a living body and to generate signals responsively to the waves that are scattered from within the body, and which includes an array of antenna elements, each antenna element including a planar element at the front surface of the antenna and a cavity behind the planar element.
- Processing circuitry is configured to process the signals so as to locate a feature in the body.
- the front surface of the antenna includes a printed circuit board, and the planar element of each antenna element includes a conductive radiator printed on the printed circuit board.
- the printed circuit board may include multiple conductive vias surrounding the radiator for isolating the antenna elements from one another.
- diagnostic apparatus including an antenna, including an array of antenna elements, which are configured to direct radio frequency (RF) electromagnetic waves into a living body and to generate signals responsively to the waves that are scattered from within the body.
- Excitation circuitry is coupled to apply a RF excitation waveform at multiple different frequencies to different transmitting antenna elements, selected from the array, according to a predetermined temporal pattern.
- Processing circuitry is coupled to receive the signals from different receiving antenna elements, selected from the array, and to process the signals at the different frequencies due to the different transmitting and receiving antenna elements so as to locate a feature in the body.
- the excitation circuitry includes a driver circuit, which is configured to generate the RF excitation waveform with a variable frequency, and a switching matrix, which is configured to select sets of the antenna elements in alternation, each set including at least one transmitting antenna element and one receiving antenna element, and for each selected set, to couple the driver circuit to excite the at least one transmitting antenna element at a selected frequency while coupling the processing circuitry to receive the signals from the at least one receiving antenna element.
- the driver circuit and the switching matrix are coupled to select pairs of one transmitting antenna element and one receiving antenna element, and to excite the transmitting antenna in each pair at each of a plurality of frequencies in accordance with the predetermined temporal pattern.
- the apparatus includes a signal conditioning unit, which is configured to cancel a background component of the signals that arises from direct coupling between the transmitting and receiving antenna elements before the processing circuitry receives the signals.
- the signal conditioning unit may include an amplitude and phase modulator, which is coupled to receive the RF excitation waveform from the driver circuit, to modify a phase and amplitude of the received waveform so as to generate an anti-phased signal matching the background component, and to add the anti-phased signal to a signal received from the at least one receiving antenna element in order to cancel the background component.
- the processing circuitry is configured to transform the signals received at the different frequencies due to the different transmitting and receiving antenna elements into a three-dimensional (3D) image, and to process the 3D image in order to find a location of the feature.
- the processing circuitry is configured to compute a weighted sum of the signals received at the different frequencies due to the different transmitting and receiving antenna elements, using respective weights provided for a plurality of voxels in the 3D image, to determine values of the voxels in the 3D image.
- a method for diagnosis including directing radio frequency (RF) electromagnetic waves into a living body and generating signals responsively to the waves that are scattered from within the body.
- the signals are processed so as to locate a feature in a blood vessel in the body.
- RF radio frequency
- a method for diagnosis including spreading a dielectric gel between an outer surface of a living body and a front surface of an antenna.
- the front surface of the antenna is brought into contact, via the dielectric gel, with the outer surface of the living body so as to direct radio frequency (RF) electromagnetic waves into the body and to generate signals in the antenna responsively to the waves that are scattered from within the body.
- the signals are processed so as to locate a feature in the body.
- RF radio frequency
- a method for diagnosis including providing an antenna, which has a front surface and which includes an array of antenna elements, each antenna element including a planar element at the front surface of the antenna and a cavity behind the planar element.
- Radio frequency (RF) electromagnetic waves are directed from the antenna elements via the front surface of the antenna into a living body and generating signals, using the antenna elements, responsively to the waves that are scattered from within the body.
- the signals are processed so as to locate a feature in the body.
- RF radio frequency
- a method for diagnosis including defining a temporal pattern specifying a sequence of multiple different frequencies and spatial channels associated with an array of antenna elements.
- Radio frequency (RF) electromagnetic waves are directed at the multiple different frequencies into a living body from multiple different transmitting antenna elements that are selected from the array in accordance with the temporal pattern.
- Signals are generated responsively to the waves that are scattered from within the body and are received at multiple different receiving antenna elements that are selected from the array in accordance with the temporal pattern.
- the signals from the different receiving antenna elements at the different frequencies are processed so as to locate a feature in the body.
- FIG. 1 is a schematic, pictorial illustration of a system for tracking and assessment of a feature in a human body, in accordance with an embodiment of the present invention
- FIG. 2 is a block diagram that schematically shows elements of a system for tracking and assessment of a feature in a human body, in accordance with an embodiment of the present invention
- FIG. 3 is a schematic, pictorial illustration of an antenna array, in accordance with an embodiment of the present invention.
- FIG. 4 is a schematic, exploded view of an antenna element, in accordance with an embodiment of the present invention.
- FIG. 5 is a block diagram that schematically illustrates a feature detection subsystem, in accordance with an embodiment of the present invention
- FIG. 6 is a timing diagram that schematically illustrates an excitation pattern that is applied to an antenna array, in accordance with an embodiment of the present invention.
- FIG. 7 is a flow chart that schematically illustrates a method for measuring blood flow through a stent, in accordance with an embodiment of the present invention.
- Embodiments of the present invention that are described hereinbelow use radar imaging techniques to identify and locate features in the body. Features are thus identified based on the difference in their complex dielectric constant (referring to both permittivity and conductivity) relative to the dielectric constant of the surrounding tissue. These techniques are particularly useful in detecting and tracking metal objects in the body, but they may also be used to locate features of other kinds, including both introduced objects, such as plastic objects, and naturally-occurring features, such as calcifications, and even pockets of air or other gases.
- feature as used in the context of the present patent application and in the claims, should therefore be understood as referring to any item or location in the body having a distinct dielectric constant.
- Some embodiments of the present invention are directed to locating features in the heart, and particularly in the coronary blood vessels.
- an antenna directs RF electromagnetic waves toward the heart and receives the waves that are scattered from within the body.
- Processing circuitry processes the signals generated by the antenna due to the received waves in order to locate the feature or features of interest, and possibly to track the movement of such features over the course of the heart cycle.
- the radar-based location of a feature may be used in guiding the beam of an ultrasound transducer toward the feature.
- the antenna and processing circuitry find the location of a stent in an artery and guide the ultrasound transducer to direct its beam toward the stent.
- the ultrasound transducer may operate in Doppler mode in order to measure the flow of blood through the stent and thus non-invasively assess possible restenosis in the stent.
- the antenna comprises an array of antenna elements, with a front surface that is brought into contact with the outer surface (i.e., the skin) of the patient's body.
- a dielectric gel may be spread between the body surface and the front surface of the antenna in order to match the dielectric constants and thus improve the penetration of the RF waves into the body.
- the antenna elements may comprise a cavity and possibly other features to enhance the efficiency of coupling of electromagnetic energy from the antenna elements into the body while reducing loss and crosstalk between the elements.
- excitation circuitry applies a RF excitation waveform at multiple different frequencies to different transmitting antenna elements in the array.
- the processing circuitry receives signals from different receiving antenna elements.
- the selection of transmitting and receiving antennas, as well as the selection of excitation frequency, follows a predetermined temporal pattern, which may be implemented by a switching matrix connected to the antenna elements.
- the processing circuitry receives and processes signals from multiple spatial channels (corresponding to different pairs of antennas) at multiple different frequencies for each channel. Taken together in the time domain, these multi-frequency signals are equivalent to short pulses of RF energy.
- the processing circuitry applies a spatial transform to the set of received signals.
- the transform may, for example, comprise an inverse spherical Radon transform or an algebraic approximation of such a transform.
- a signal conditioning unit is used to adaptively cancel the background component out of the signals that are passed to the processing circuitry.
- the signal conditioning unit or another element of the processing circuitry may even be configured to cancel all parts of the signals that do not vary over time.
- FIG. 1 is a schematic, pictorial illustration of a system 20 for tracking and assessment of a feature in a body of a patient 26 , in accordance with an embodiment of the present invention.
- an operator 22 such as a physician, directs an ultrasonic beam from an ultrasound transducer 24 into the chest of patient 26 .
- the probe containing transducer 24 operates in Doppler mode, as is known in the art, in order to measure the velocity of blood flowing through a coronary artery of the patient, and specifically through a stent (not shown) that is implanted in one of the patient's coronary arteries.
- a console 28 drives transducer 24 and processes the signals that are output by the transducer in order to extract the Doppler information and displays the results on a monitor 30 .
- the operator steers the probe toward the location of the stent under guidance from system 20 , as explained in detail hereinbelow.
- system 20 uses radar imaging in order to find the location of the stent and guide operator 22 .
- an antenna 32 directs RF waves into the patient's chest.
- a layer of a dielectric gel 33 is spread between the front surface of the antenna and the patient's skin.
- the gel may also have adhesive qualities, in order to aid in holding the antenna in place during the procedure.
- gel 33 has a dielectric constant that is between 30 and 75. This value defines the effective dielectric constant of the antenna in its near-field. It is chosen to be close to the effective dielectric constant of the tissue layers in the path to the target region in the body.
- the desired dielectric constant may be achieved by increasing or decreasing the concentration of certain additives in the gel.
- the additive may be an alcohol (such as ethanol), salt, sugar, or glycerin.
- a silicone gel may be used with an additive such as barium, having generally a dielectric constant greater than 70.
- Antenna 32 is coupled by a cable or wireless link to a radar control unit 34 .
- the control unit comprises processing circuitry 36 , which drives the antenna to emit the RF waves into the body and processes the signals generated by the antenna due to reception of scattered waves from the body. Based on the received signals, circuitry 36 forms a 3D radar image of the interior of the body, and specifically, in the present embodiment, finds the location of the stent. These functions of circuitry 36 are described in detail hereinbelow.
- system 20 includes a tracking subsystem, comprising a tracking transmitter 38 , which generates a field that is detected by sensors 40 and 42 on the antenna and on the ultrasound transducer, respectively.
- Transmitter 38 may, for example, generate a magnetic field
- sensors 40 and 42 may be magnetic sensors, as in the trakSTARTM system distributed by Ascension Technology Corporation (Milton, Vt.).
- sensors 40 and 42 may be replaced by transmitting elements, which generate fields that are detected by a fixed sensor.
- position transducer is used herein to refer to the elements that are attached to ultrasound transducer 24 and antenna 32 , such as sensors 40 and 42 , for the purpose of finding their coordinates, regardless of the specific choice of position sensing technology.
- ultrasonic transducer 24 and antenna 32 may be mechanically fixed in a common frame of reference.
- sensors 40 and 42 output signals to processing circuitry 36 .
- the processing circuitry processes the signals to find location and orientation coordinates of the sensors, and hence of antenna 32 and transducer 42 , in a common coordinate frame. Based on these coordinates, processing circuitry 36 registers the ultrasonic images formed by transducer 24 with the radar images formed by antenna 32 .
- the processing circuitry finds the location of the stent in the radar image, and may also estimate its orientation. On this basis, the circuitry guides operator 22 to aim transducer 24 toward the stent along the stent axis, i.e., along the direction of blood flow, in order to maximize the Doppler component in the ultrasound signals.
- the processing circuitry drives a guidance display 44 , which indicates to the operator how to aim the ultrasound transducer toward the target.
- ultrasound transducer 24 may be held and manipulated by a robot arm, which is guided automatically by processing circuitry to aim the transducer in the desired direction.
- FIG. 1 shows a particular type of antenna and mode of coupling the antenna to the patient's body
- the antenna may mounted in a cushion below the patient's back, in a wearable element that fits over the patient's body, or in any other suitable mount.
- Some alternative configurations of this sort are shown in the above-mentioned U.S. patent application Ser. No. 12/127,544.
- FIG. 2 is a block diagram that schematically shows key elements of system 20 , and particularly of processing circuitry 36 , in accordance with an embodiment of the present invention. Some of these elements are described in greater detail hereinbelow.
- Antenna 32 is driven by and outputs signals to a feature detection subsystem 50 .
- the antenna typically comprises an array of antenna elements 48 , which are connected to a switching matrix 54 in a front end 52 of subsystem 50 .
- the switching matrix selects different sets of the antennas to transmit and receive signals at different, respective times and frequencies, in a predetermined temporal pattern. Typically, the sets comprise pairs of antennas—one transmitting and one receiving—although other groupings may also be used.
- the pattern of antenna control is described in detail hereinbelow.
- a driver circuit 58 generates signals, at multiple different frequencies, for exciting the transmitting antennas and demodulates the signals received by the receiving antennas. Typically, the signals are in the range of about 400 MHz to about 4 GHz, although higher and lower frequencies outside this range may also be used.
- a signal conditioning unit 56 between the driver circuit and switching matrix 54 amplifies the outgoing and the incoming signals and also cancels background components in the received signals. This functionality is also described below.
- Front end 52 outputs the demodulated received signals (as intermediate-frequency or baseband signals) to a digital data acquisition unit 60 , which samples and digitizes the signals.
- Unit 60 typically comprises a high-resolution analog/digital converter, such as a 14-bit converter, with suitable sampling circuits as are known in the art.
- a target detection, measurement and tracking unit 62 receives and processes the digital samples.
- Unit 62 processes the sampled signals in order to generate a 3D radar image of the interior of the chest of patient 26 .
- unit 62 identifies and measures the location coordinates of the stent relative to antenna 32 .
- unit 62 may also track and model the motion of the stent in order to more precisely guide ultrasound transducer 24 .
- the direction of motion of the stent during the heart cycle also gives an indication of the direction of the stent axis (along which the ultrasound transducer should be aimed): Since the axis of the stent is oriented along the coronary artery in which the stent is implanted, and the coronary artery runs along the heart wall, the stent axis will typically be perpendicular to the direction of motion of the heart wall, and hence to the axis of motion of the stent in the radar image. As noted above, operator 22 is guided to aim ultrasound transducer 24 toward the stent in a direction along, or at least close to, the stent axis.
- the present embodiment relates specifically to identification and tracking of a stent
- the techniques and circuits that are described here may be used, by the same token, in locating and tracking other features in the coronary blood vessels, such as calcifications, as well as features elsewhere in the body.
- a tracking unit 64 communicates with tracking transmitter 38 and receives position signals from position sensors 40 and 42 .
- the tracking unit processes these signals in order to compute the coordinates of ultrasound transducer 24 and antenna 32 in the frame of reference of transmitter 38 .
- the tracking unit may be a commercially-available device, such as in the above-mentioned FASTRAK system.
- a guidance processor 66 receives the position (location and orientation) coordinates from tracking unit 64 and the position coordinates of the stent from feature detection subsystem 50 .
- Guidance processor 66 registers the coordinates of the stent in the coordinate frame of the tracking unit or, equivalently, registers the coordinates of ultrasound transducer 24 in the coordinate frame of antenna 32 , in which the stent coordinates have been found.
- the guidance processor is then able to compute the geometrical skew and offset between the present viewing axis of the ultrasound transducer and the desired viewing axis, which will intercept the stent along (or close to) the stent axis. Based on the computed skew and offset, the guidance processor may drive guidance display 44 to show operator 22 the required correction.
- the guidance display may show, for example, target crosshairs and directional arrows, or any other suitable sort of directional indication.
- console 28 may use the computed skew in adjusting the Doppler velocity readings to account for the angle of measurement relative to the flow.
- Processing circuitry 36 typically comprises a combination of dedicated hardware circuits (such as in front end 52 and digital data acquisition unit 60 ) and programmable components. The front end circuits are described in detail hereinbelow.
- Target detection, measurement and tracking unit 62 and guidance processor 66 typically comprise programmable processors, such as a general-purpose microprocessor or a digital signal processor, which are programmed in software to carry out the functions that are described herein.
- these elements of circuitry 36 may comprise dedicated or programmable digital logic units such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).
- ASIC application-specific integrated circuit
- FPGA field-programmable gate array
- units 62 and 64 and processor 66 are shown, for the sake of conceptual clarity, as separate functional blocks, in practice at least some of the functions of these different blocks may be carried out by a single processor. Alternatively, the functions of a given block may be divided up among two or more separate processors.
- FIG. 3 is a schematic, pictorial illustration of antenna 32 , in accordance with an embodiment of the present invention.
- Antenna 32 is a planar ultra-wideband, unidirectional antenna, comprising an array of antenna elements 48 .
- the antenna is designed for high-permittivity surroundings, enabling transmission and reception of ultra-wideband signals to and from the human body with minimal loss.
- the antenna comprises twelve antenna elements 48 , which are spread in a rectangular plane to allow Cartesian acquisition of an image.
- the antenna may comprise a larger or smaller number of antenna elements, in a rectangular or non-rectangular array.
- Each antenna element 48 comprises a planar element comprising a conductive radiator 70 , which is printed on a circuit board 72 .
- This circuit board serves as the front surface of antenna, which is brought into contact with the patient's body.
- Circuit board 72 comprises multiple conductive vias 74 surrounding each radiator 70 for isolating antenna elements 48 from one another. The antenna elements are enclosed from behind by a case 76 .
- FIG. 4 is a schematic, exploded view of one of antenna elements 48 , in accordance with an embodiment of the present invention.
- Each antenna element is constructed as an ellipse-shaped slotted antenna, excited electrically at its center feed point.
- Circuit board 72 comprises a dielectric substrate, such as an FR4 laminate, with a component (front) side that includes radiator 70 and a ground plane 80 .
- the radiator shape is optimized with an elliptical template to maintain a low voltage standing wave ratio (VSWR), with high antenna gain and flatness at boresight. This flatness assures good coverage of the entire region of interest (ROI) in the patient's body with constant antenna gain.
- VSWR voltage standing wave ratio
- the printed (rear) side of board 72 includes an excitation transmission line 82 feeding the center point of radiator 70 through a conductive via.
- Transmission line 82 comprises a fifty-ohm microstrip, with a micro-miniature coaxial (MMCX) connector (not shown) for connecting to front end 50 .
- MMCX micro-miniature coaxial
- a conductive cavity 84 is attached to the component side of board 72 behind each radiator 70 in order to reduce antenna reverberations from back-lobe scattering and to increase the overall gain.
- Antenna element 48 as shown in FIG. 4 has a nominal gain of 7 dBi at boresight.
- Cavity 84 comprises a hollow waveguide 86 , with dimensions designed such that the cutoff frequency of the lowest propagating mode (TE10) in the waveguide is higher than the upper band frequency limit of antenna 32 ,
- C 0 is the speed of light
- ⁇ r is the permittivity of the interior of the waveguide
- a is the largest transverse dimension of the waveguide.
- the depth of waveguide 86 is 15 mm.
- the waveguide creates an imaginary characteristic impedance, causing back-lobe radiation from radiator 70 to reflect from the cavity in phase with the back-lobe waves. This reflection enhances the external buffering of the antenna and attenuates non-TE and TM modes, and therefore reduces interference and noise.
- Cross-coupling between antenna elements 48 can cause interference, which reduces the dynamic range and may saturate the receiver circuits.
- This cross-coupling is reduced in antenna 32 by appropriately setting the distance between the antenna elements in the array and by surrounding radiators 70 with conductive vias 74 , as noted above.
- the vias serve as an electric wall that prevents internal waves from traveling between elements. They also create a conductive continuity between ground plane 80 on the component side of board 72 and the top conductive transverse plane of waveguide 86 located on the print side.
- Antenna 32 is sealed against liquids and gels, thus preventing unwanted materials from reaching the print side and cavities of the antenna elements.
- Case 76 including cavities 84 , can be constructed from a molded plastic with a suitable conducting coating. Additionally or alternatively, the antenna elements may be printed on the molded plastic after coating.
- switching matrix 54 is shown and described herein as a part of processing circuitry 36 , it may alternatively be incorporated into antenna 32 or mounted adjacent to the antenna, thereby performing the switching alongside the patient and reducing the weight and rigidity of the cable from the antenna to control unit 34 .
- antenna 32 is shown here as a unitary assembly containing antenna elements 48 , the antenna elements (of similar design to that shown in FIG. 4 ) may alternatively be used singly or as dual- or multi-element panels, which can be attached to different body locations. Multiple position sensors can be used to compute and register the respective positions of the antenna elements. In such embodiments, system 20 may be configured to measure and analyze both waves reflected from the region of interest of the body and waves transmitted through the region and scattered by the target.
- FIG. 5 is a block diagram that schematically shows details of feature detection subsystem 50 , in accordance with an embodiment of the present invention.
- switching matrix 54 connects antenna elements 48 to the other circuits of front end 52 .
- Each antenna element connects to a respective single-pole double-throw (SPDT) switch 90 , which determines whether the switch is to transmit or to receive waves at any given time.
- SPDT single-pole double-throw
- the transmit antenna element is selected, from among the multiple antenna elements, by a transmit switch 92 , while the receive antenna element is selected by a receive switch 94 .
- the switching matrix thus permits any pair of the antenna elements to be selected as the transmitter and receiver at any given time.
- Switching matrix 54 is designed for high isolation between channels, typically better than 40 dB over the entire frequency range of antenna 32 .
- Switches 90 , 92 and 94 are digitally controlled by a digital output control module 104 and allow fast (non-mechanical) switching. This fast switching is required in order to allow the entire waveform sequence of different antenna pairs and frequencies to be completed in a short frame time, as described hereinbelow.
- matrix 54 is typically configured to achieve a switching time of less than 1 ⁇ s.
- Driver circuit 58 comprises a broadband signal generator 98 , which generates the RF excitation waveform to drive the transmitting antenna elements, and a receiver 114 , which receives and demodulates the signals generated by the receiving antenna elements.
- Signal generator 98 and receiver 114 are both synchronized and sweep their frequencies according to a predefined frequency plan, which is shown in FIG. 6 , based on a shared local oscillator 96 .
- the frequency plan specifies the frequencies and power levels to be generated by the signal generator, in synchronization with an external trigger.
- the driving waveform entering signal conditioning unit 56 from signal generator 98 is sampled by a broadband coupler 100 , amplified by a power amplifier 102 according to the required transmit power level, and transferred to switching matrix 54 .
- Receiver 114 is a tuned super-heterodyne receiver, which is able to adjust its bandwidth and gain according to the received signal.
- the receiver demodulates the received signals coherently, in synchronization with local oscillator 96 , in order to extract both the amplitude and the phase of the signals.
- the complex ratio between the transmitted and received signals, as measured by detection, measurement and tracking unit 62 for each antenna pair at each selected frequency, indicates the frequency response along corresponding paths through the region of interest. This region includes the chest, thoracic cavity, beating heart and the stent itself.
- the signals received from antenna 32 by signal conditioning unit 56 may still include a strong background component due to the direct coupling between the transmitting and receiving antenna elements.
- This background component raises the noise level due to transmitter nonlinearity and impurities in the transmitted signal and can even cause receiver 114 to saturate. It is therefore desirable to reduce the level of the background component that reaches the receiver in order to enhance the dynamic range of the radar image.
- signal conditioning unit 56 comprises an amplitude and phase modulator, referred to here as an IQ modulator 108 , which receives the sampled RF excitation waveform from coupler 100 .
- the IQ modulator modifies the phase and amplitude of the sampled signal, under the control of an analog output control module 110 , so as to generate an anti-phased signal matching the background component that is to be canceled.
- the amplitude and phase values of IQ modulator 108 are periodically updated and are then kept constant per frequency and per channel until coupling values change significantly and need updating.
- IQ modulator 108 outputs a signal that is equal in amplitude to the background component but 180° out of phase.
- a coupler 106 adds this anti-phased signal to the received signal from switching matrix 54 and thus cancels the background component without degrading the actual radar signal from the body.
- An amplifier 112 amplifies the signal following background cancellation for input to receiver 114 .
- FIG. 6 is a timing diagram that schematically illustrates a temporal excitation pattern that front end 52 applies to antenna 32 , in accordance with an embodiment of the present invention.
- the front end generates a sequence of frames 120 .
- Each frame 120 comprises multiple frequency sub-frames 122 according to the number of frequencies to be used in image reconstruction. In the example shown in FIG. 6 , there are 128 such sub-frames, each lasting 750 ⁇ s.
- the frequencies in this example span the range between 400 MHz and 4 GHz.
- Each sub-frame 122 begins with a settling time 126 (typically a few hundred microseconds) for locking the amplitude and phase of signal generator 98 .
- switching matrix 54 selects different channels 124 in sequence.
- Each channel uses one transmitting antenna element and one receiving antenna element, up to a total of n channels (for example, one hundred such channels in the example shown in FIG. 6 , each open for 5 ⁇ s).
- detection, measurement and tracking unit 62 collects samples of the received signal from receiver 114 for subsequent use in multi-frequency/multi-channel radar image reconstruction.
- a selected antenna element may serve as both transmitter and receiver, as opposed to bistatic or multistatic configurations, in which each antenna either transmits or receives.
- antenna elements may simply transmit and receive broadband RF pulses, rather than multiple narrowband pulses as in the embodiment described above.
- detection, measurement and tracking unit 62 Based on the collected samples of the received signals, detection, measurement and tracking unit 62 detects small reflecting volumes within the region of interest (ROI) in the patient's body. As noted above, the corresponding reflections arise at the boundaries of media having different dielectric properties.
- the information provided by coherent detection of the signals over the broad range of frequencies covered in each frame is equivalent mathematically to the temporal information that would be provided by reflection of a single short pulse.
- the locations of the reflectors may be found by integrating over the propagation paths of the reflected waves, using an inverse spherical Radon transformation, for example.
- detection, measurement and tracking unit 62 implements a first-order approximation of the inverse spherical Radon transform: For each voxel (x, y, z) in the ROI and for each frequency f and pair of antenna elements, a complex weight W(x,y,z,f,pair) is pre-calculated, either using an empirical calibration procedure or mathematical modeling.
- the weight is, in effect, the normalized complex amplitude (with conjugated phase) of the reflection that would be received at the receiving antenna in the pair from a point object at location (x,y,z) when irradiated by the transmitting antenna with a wave of frequency f. Because the body tissue through which the waves propagate is inhomogeneous, the weights may be adjusted, either empirically or by model calculation, to account for the specific tissue layers (skin, fat, muscle, lungs, etc.) through which the waves pass.
- the set of weights thus derived defines a sort of matched filter. Detection, measurement and tracking unit 62 applies this filter to the matrix of complex signals Sig(f,pair) that it receives in any given frame in order to compute the reflection intensity V for each voxel, as a weighted sum over the received signals:
- V ⁇ ( x , y , z ) ⁇ pair ⁇ ⁇ ⁇ f ⁇ ⁇ W ⁇ ( x , y , z , pair , f ) ⁇ Sig ⁇ ( pair , f ) ( 1 )
- FIG. 7 is a flow chart that schematically illustrates a method for measuring blood flow through a stent, in accordance with an embodiment of the present invention.
- the method is described hereinbelow, for the sake of clarity, with reference to the elements of system 20 that have been described above, but the same techniques may similarly be implemented in other system configurations.
- the elements of this method that relate to locating the stent in the body of patient 26 may likewise be applied, mutatis mutandis, for locating other features, both natural and artificial, in the coronary blood vessels, as well as elsewhere in the body.
- Front end 52 drives antenna 32 to emit and receive RF waves over multiple frequencies and spatial channels (antenna pairs), at a scanning step 130 , as described above.
- Detection, measurement and tracking unit 62 collects samples of the received signals and applies the weights defined in equation (1) to transform the signal values to voxel intensities, at an image reconstruction step 132 .
- the processing circuitry may apply additional image processing operations, such as subtracting the mean voxel value from all voxels in the image.
- the mean value may be smoothed over multiple successive images using a recursive filter.
- Unit 62 then identifies the coordinates of the target feature, i.e., the stent or another strong reflector, in the 3D image, at a target identification step 134 .
- detection, measurement and tracking unit 62 tracks the motion of the target in the successive images, at a target tracking step 136 .
- unit 62 may apply a Kalman filter, as is known in the art, to estimate the motion trajectory of the target.
- Guidance processor 66 registers the coordinates of ultrasound transducer 24 with antenna 32 , at a coordinate registration step 138 .
- the processor uses the position coordinates provided by position sensors 40 and 42 at this step, as explained above. Based on these coordinates, the processor registers the ultrasound beam in the coordinate frame of the 3D image that was reconstructed at step 132 .
- Guidance processor 66 drives guidance display 44 to guide operator 22 in aiming the ultrasound beam toward the target, at an aiming step 140 . It could be possible but would probably be impractical for a human operator, to move ultrasound transducer 24 continually back and forth in synchronism with the motion of the heart. (Such tracking could be feasible for a robot driven by the processing circuitry.) To alleviate this difficulty, the guidance processor selects a single location within the trajectory of motion found at step 136 and guides the operator to aim at the selected location. Console 28 measures the flow through the stent at this location, at a flow measurement step 142 , and thus provides an indication of the extent of any restenosis.
- guidance processor 66 may, for example, find the center of mass of the trajectory found at step 136 , and then choose a point that is displaced from the center toward the end of the trajectory that has the greater dwell time, which is the diastolic end. Blood flow through the coronary arteries occurs mainly during diastole, so that the diastolic end of the trajectory will give the strongest Doppler signal. Furthermore, aiming the ultrasound transducer toward the end of the trajectory with the greater dwell permits the ultrasonic beam to capture the stent for a longer part of each heart cycle and thus improves the signal/noise ratio.
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Heart & Thoracic Surgery (AREA)
- Veterinary Medicine (AREA)
- Public Health (AREA)
- Biophysics (AREA)
- General Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Animal Behavior & Ethology (AREA)
- Cardiology (AREA)
- Surgery (AREA)
- Medical Informatics (AREA)
- Pathology (AREA)
- Physics & Mathematics (AREA)
- Molecular Biology (AREA)
- Radiology & Medical Imaging (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Physiology (AREA)
- Hematology (AREA)
- Radar Systems Or Details Thereof (AREA)
- Ultra Sonic Daignosis Equipment (AREA)
- Pulmonology (AREA)
- Vascular Medicine (AREA)
- Dentistry (AREA)
- Oral & Maxillofacial Surgery (AREA)
Abstract
Diagnostic apparatus (20) includes an antenna 32, which is configured to direct radio frequency (RF) electromagnetic waves into a living body and to generate signals responsively to the waves that are scattered from within the body. Processing circuitry (36) is configured to process the signals so as to locate a feature in a blood vessel in the body.
Description
- This application is a continuation-in-part of U.S. patent application Ser. No. 12/127,544, filed May 27, 2008, which is assigned to the assignee of the present patent application and whose disclosure is incorporated herein by reference.
- The present invention relates generally to methods and systems for medical diagnostic imaging, and specifically to radio frequency (RF)-based imaging.
- Narrowing of the coronary arteries due to atherosclerosis is commonly treated by implantation of a stent, using a catheter, to hold the artery open. In a large fraction of cases, however, the treated artery closes up again due to in-stent restenosis, necessitating further treatment. Accurate assessment of such restenosis generally requires re-catheterization. A number of non-invasive techniques have been proposed, such as in U.S. Pat. No. 6,729,336, in which an electromagnetic wave transmitter is used to excite a stent, and an acoustic sensor detects stent acoustic oscillations.
- RF imaging is best known in the context of radar systems, but RF diagnostic imaging systems have also been developed for medical applications. For example, U.S. Patent Application Publication 2008/0169961, whose disclosure is incorporated herein by reference, describes computerized tomography using radar, which may be used for generating an image of living tissue. As another example, U.S. Pat. No. 7,454,242, whose disclosure is incorporated herein by reference, describes tissue-sensing adaptive radar imaging for breast tumor detection.
- Various antenna designs have been proposed for RF imaging of body tissues. For example, U.S. Pat. No. 6,061,589, whose disclosure is incorporated herein by reference, describes a microwave antenna for use in a system for detecting an incipient tumor in living tissue, such as that of a human breast, in accordance with differences in relative dielectric characteristics. A composite Maltese Cross or bow-tie antenna construction is employed to irradiate the living tissue and to collect backscatter or other scatter returns.
- Embodiments of the present invention that are described hereinbelow provide improved devices and methods for detecting features inside a living body using RF imaging techniques. Although some of these embodiments are directed specifically to detection of features in the heart, and specifically in the coronary arteries, the principles of these embodiments may similarly be applied in imaging, detection and tracking of features elsewhere in the body.
- There is therefore provided, in accordance with an embodiment of the present invention, diagnostic apparatus, including an antenna, which is configured to direct radio frequency (RF) electromagnetic waves into a living body and to generate signals responsively to the waves that are scattered from within the body. Processing circuitry is configured to process the signals so as to locate a feature in a blood vessel in the body.
- In disclosed embodiments, the apparatus includes an ultrasound transducer, and the processing circuitry is configured to guide the ultrasound transducer to direct an ultrasonic beam toward the feature. In one embodiment, the feature located by the processing circuitry includes a stent, and the ultrasound transducer is configured to generate a Doppler signal responsively to a flow of blood through the stent.
- Additionally or alternatively, the apparatus includes a tracking unit, which is configured to track respective coordinates of the antenna and of the ultrasound transducer, and the processing circuitry is configured to guide the ultrasound transducer responsively to the respective coordinates. The apparatus typically includes position transducers fixed respectively to the ultrasound transducer and to the antenna, wherein the tracking unit is configured to track the respective coordinates responsively to position signals exchanged between the position transducers and the tracking system.
- Further additionally or alternatively, the apparatus includes a display, wherein the processing circuitry is configured to guide the ultrasound transducer by driving the display to present to an operator of the ultrasound transducer an indication of a direction in which the ultrasound transducer should be aimed.
- In a disclosed embodiment, the blood vessel is a coronary artery. The processing circuitry may be configured to track a cyclical motion of the feature over multiple cycles of the heart.
- Typically, the processing circuitry is configured to locate the feature responsively to a difference in a dielectric constant of the feature relative to surrounding tissue.
- There is also provided, in accordance with an embodiment of the present invention, diagnostic apparatus, including an antenna, having a front surface configured to brought into contact with an outer surface of a living body so as to direct radio frequency (RF) electromagnetic waves into the body and to generate signals responsively to the waves that are scattered from within the body. A dielectric gel is adapted to be spread between the outer surface of the body and the front surface of the antenna. Processing circuitry is configured to process the signals so as to locate a feature in the body.
- Typically, the body has a first dielectric constant, and the gel has a second dielectric constant that is chosen to match the first dielectric constant. In disclosed embodiments, the gel has a dielectric constant that is between 30 and 75. The gel may be adhesive.
- In one embodiment, the gel is water-based and includes an additive selected from a group of additives consisting of an alcohol, a salt, a sugar, and glycerin. Alternatively, the gel includes silicone and an additive having a dielectric constant greater than 70.
- There is additionally provided, in accordance with an embodiment of the present invention, diagnostic apparatus, including an antenna, which has a front surface and is configured to direct radio frequency (RF) electromagnetic waves from the front surface into a living body and to generate signals responsively to the waves that are scattered from within the body, and which includes an array of antenna elements, each antenna element including a planar element at the front surface of the antenna and a cavity behind the planar element. Processing circuitry is configured to process the signals so as to locate a feature in the body.
- In disclosed embodiments, the front surface of the antenna includes a printed circuit board, and the planar element of each antenna element includes a conductive radiator printed on the printed circuit board. The printed circuit board may include multiple conductive vias surrounding the radiator for isolating the antenna elements from one another.
- There is further provided, in accordance with an embodiment of the present invention, diagnostic apparatus, including an antenna, including an array of antenna elements, which are configured to direct radio frequency (RF) electromagnetic waves into a living body and to generate signals responsively to the waves that are scattered from within the body. Excitation circuitry is coupled to apply a RF excitation waveform at multiple different frequencies to different transmitting antenna elements, selected from the array, according to a predetermined temporal pattern. Processing circuitry is coupled to receive the signals from different receiving antenna elements, selected from the array, and to process the signals at the different frequencies due to the different transmitting and receiving antenna elements so as to locate a feature in the body.
- In some embodiments, the excitation circuitry includes a driver circuit, which is configured to generate the RF excitation waveform with a variable frequency, and a switching matrix, which is configured to select sets of the antenna elements in alternation, each set including at least one transmitting antenna element and one receiving antenna element, and for each selected set, to couple the driver circuit to excite the at least one transmitting antenna element at a selected frequency while coupling the processing circuitry to receive the signals from the at least one receiving antenna element. In a disclosed embodiment, the driver circuit and the switching matrix are coupled to select pairs of one transmitting antenna element and one receiving antenna element, and to excite the transmitting antenna in each pair at each of a plurality of frequencies in accordance with the predetermined temporal pattern.
- In some embodiments, the apparatus includes a signal conditioning unit, which is configured to cancel a background component of the signals that arises from direct coupling between the transmitting and receiving antenna elements before the processing circuitry receives the signals. The signal conditioning unit may include an amplitude and phase modulator, which is coupled to receive the RF excitation waveform from the driver circuit, to modify a phase and amplitude of the received waveform so as to generate an anti-phased signal matching the background component, and to add the anti-phased signal to a signal received from the at least one receiving antenna element in order to cancel the background component.
- In disclosed embodiments, the processing circuitry is configured to transform the signals received at the different frequencies due to the different transmitting and receiving antenna elements into a three-dimensional (3D) image, and to process the 3D image in order to find a location of the feature. In one embodiment, the processing circuitry is configured to compute a weighted sum of the signals received at the different frequencies due to the different transmitting and receiving antenna elements, using respective weights provided for a plurality of voxels in the 3D image, to determine values of the voxels in the 3D image.
- There is moreover provided, in accordance with an embodiment of the present invention, a method for diagnosis, including directing radio frequency (RF) electromagnetic waves into a living body and generating signals responsively to the waves that are scattered from within the body. The signals are processed so as to locate a feature in a blood vessel in the body.
- There is furthermore provided, in accordance with an embodiment of the present invention, a method for diagnosis, including spreading a dielectric gel between an outer surface of a living body and a front surface of an antenna. The front surface of the antenna is brought into contact, via the dielectric gel, with the outer surface of the living body so as to direct radio frequency (RF) electromagnetic waves into the body and to generate signals in the antenna responsively to the waves that are scattered from within the body. The signals are processed so as to locate a feature in the body.
- There is also provided, in accordance with an embodiment of the present invention, a method for diagnosis, including providing an antenna, which has a front surface and which includes an array of antenna elements, each antenna element including a planar element at the front surface of the antenna and a cavity behind the planar element. Radio frequency (RF) electromagnetic waves are directed from the antenna elements via the front surface of the antenna into a living body and generating signals, using the antenna elements, responsively to the waves that are scattered from within the body. The signals are processed so as to locate a feature in the body.
- There is additionally provided, in accordance with an embodiment of the present invention, a method for diagnosis, including defining a temporal pattern specifying a sequence of multiple different frequencies and spatial channels associated with an array of antenna elements. Radio frequency (RF) electromagnetic waves are directed at the multiple different frequencies into a living body from multiple different transmitting antenna elements that are selected from the array in accordance with the temporal pattern. Signals are generated responsively to the waves that are scattered from within the body and are received at multiple different receiving antenna elements that are selected from the array in accordance with the temporal pattern. The signals from the different receiving antenna elements at the different frequencies are processed so as to locate a feature in the body.
- The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which:
-
FIG. 1 is a schematic, pictorial illustration of a system for tracking and assessment of a feature in a human body, in accordance with an embodiment of the present invention; -
FIG. 2 is a block diagram that schematically shows elements of a system for tracking and assessment of a feature in a human body, in accordance with an embodiment of the present invention; -
FIG. 3 is a schematic, pictorial illustration of an antenna array, in accordance with an embodiment of the present invention; -
FIG. 4 is a schematic, exploded view of an antenna element, in accordance with an embodiment of the present invention; -
FIG. 5 is a block diagram that schematically illustrates a feature detection subsystem, in accordance with an embodiment of the present invention; -
FIG. 6 is a timing diagram that schematically illustrates an excitation pattern that is applied to an antenna array, in accordance with an embodiment of the present invention; and -
FIG. 7 is a flow chart that schematically illustrates a method for measuring blood flow through a stent, in accordance with an embodiment of the present invention. - Embodiments of the present invention that are described hereinbelow use radar imaging techniques to identify and locate features in the body. Features are thus identified based on the difference in their complex dielectric constant (referring to both permittivity and conductivity) relative to the dielectric constant of the surrounding tissue. These techniques are particularly useful in detecting and tracking metal objects in the body, but they may also be used to locate features of other kinds, including both introduced objects, such as plastic objects, and naturally-occurring features, such as calcifications, and even pockets of air or other gases. The term “feature,” as used in the context of the present patent application and in the claims, should therefore be understood as referring to any item or location in the body having a distinct dielectric constant.
- Some embodiments of the present invention are directed to locating features in the heart, and particularly in the coronary blood vessels. In these embodiments, an antenna directs RF electromagnetic waves toward the heart and receives the waves that are scattered from within the body. Processing circuitry processes the signals generated by the antenna due to the received waves in order to locate the feature or features of interest, and possibly to track the movement of such features over the course of the heart cycle.
- The radar-based location of a feature may be used in guiding the beam of an ultrasound transducer toward the feature. In one such embodiment, the antenna and processing circuitry find the location of a stent in an artery and guide the ultrasound transducer to direct its beam toward the stent. The ultrasound transducer may operate in Doppler mode in order to measure the flow of blood through the stent and thus non-invasively assess possible restenosis in the stent.
- In the embodiments that are described hereinbelow, the antenna comprises an array of antenna elements, with a front surface that is brought into contact with the outer surface (i.e., the skin) of the patient's body. A dielectric gel may be spread between the body surface and the front surface of the antenna in order to match the dielectric constants and thus improve the penetration of the RF waves into the body. Additionally or alternatively, the antenna elements may comprise a cavity and possibly other features to enhance the efficiency of coupling of electromagnetic energy from the antenna elements into the body while reducing loss and crosstalk between the elements.
- In the disclosed embodiments, excitation circuitry applies a RF excitation waveform at multiple different frequencies to different transmitting antenna elements in the array. Meanwhile, the processing circuitry receives signals from different receiving antenna elements. The selection of transmitting and receiving antennas, as well as the selection of excitation frequency, follows a predetermined temporal pattern, which may be implemented by a switching matrix connected to the antenna elements.
- As a result of this scheme of excitation and reception, the processing circuitry receives and processes signals from multiple spatial channels (corresponding to different pairs of antennas) at multiple different frequencies for each channel. Taken together in the time domain, these multi-frequency signals are equivalent to short pulses of RF energy. To reconstruct a three-dimensional (3D) image of the interior of the body and find the location of a feature or features, the processing circuitry applies a spatial transform to the set of received signals. The transform may, for example, comprise an inverse spherical Radon transform or an algebraic approximation of such a transform.
- Despite measures that are taken to reduce coupling between antenna elements within the array, this sort of direct coupling still generates a strong background component, which tends to mask the signals due to scattered waves from the body. (The term “direct coupling,” as used in the context of the present patent application and in the claims, refers to short-range passage of RF waves between antenna elements by paths other than through the region of interest in the patient's body, including coupling that occurs within the array and near-field reflections.) In order to reduce this masking and enhance the dynamic range of the signals, in some embodiments a signal conditioning unit is used to adaptively cancel the background component out of the signals that are passed to the processing circuitry. To improve visibility of moving features, such as features in the heart, the signal conditioning unit or another element of the processing circuitry may even be configured to cancel all parts of the signals that do not vary over time.
-
FIG. 1 is a schematic, pictorial illustration of a system 20 for tracking and assessment of a feature in a body of apatient 26, in accordance with an embodiment of the present invention. In this embodiment, anoperator 22, such as a physician, directs an ultrasonic beam from anultrasound transducer 24 into the chest ofpatient 26. Theprobe containing transducer 24 operates in Doppler mode, as is known in the art, in order to measure the velocity of blood flowing through a coronary artery of the patient, and specifically through a stent (not shown) that is implanted in one of the patient's coronary arteries. Aconsole 28drives transducer 24 and processes the signals that are output by the transducer in order to extract the Doppler information and displays the results on amonitor 30. The operator steers the probe toward the location of the stent under guidance from system 20, as explained in detail hereinbelow. - Aiming the ultrasound probe correctly under these circumstances is difficult: The stent is small and is typically embedded in clutter in the ultrasound image due to other anatomical features; and the stent and surrounding features of the heart are in continual motion. Therefore, system 20 uses radar imaging in order to find the location of the stent and
guide operator 22. For this purpose, anantenna 32 directs RF waves into the patient's chest. For good dielectric matching, in order to enhance the penetration of the RF waves into the body, a layer of adielectric gel 33 is spread between the front surface of the antenna and the patient's skin. The gel may also have adhesive qualities, in order to aid in holding the antenna in place during the procedure. - Typically,
gel 33 has a dielectric constant that is between 30 and 75. This value defines the effective dielectric constant of the antenna in its near-field. It is chosen to be close to the effective dielectric constant of the tissue layers in the path to the target region in the body. The desired dielectric constant may be achieved by increasing or decreasing the concentration of certain additives in the gel. For example, if a water-based gel is used, the additive may be an alcohol (such as ethanol), salt, sugar, or glycerin. Alternatively, a silicone gel may be used with an additive such as barium, having generally a dielectric constant greater than 70. -
Antenna 32 is coupled by a cable or wireless link to aradar control unit 34. The control unit comprises processingcircuitry 36, which drives the antenna to emit the RF waves into the body and processes the signals generated by the antenna due to reception of scattered waves from the body. Based on the received signals,circuitry 36 forms a 3D radar image of the interior of the body, and specifically, in the present embodiment, finds the location of the stent. These functions ofcircuitry 36 are described in detail hereinbelow. - In order to guide the direction of
ultrasound transducer 24, the position coordinates (location and orientation) of the transducer and ofantenna 32 are registered in a common coordinate frame. For this purpose, system 20 includes a tracking subsystem, comprising a trackingtransmitter 38, which generates a field that is detected bysensors Transmitter 38 may, for example, generate a magnetic field, andsensors sensors - Further alternatively, other types of tracking devices may be used, such as optical, ultrasonic or mechanical position sensing devices, as are known in the art. For the sake of generality, the term “position transducer” is used herein to refer to the elements that are attached to
ultrasound transducer 24 andantenna 32, such assensors ultrasonic transducer 24 andantenna 32 may be mechanically fixed in a common frame of reference. A variety of alternative configurations are described in the above-mentioned U.S. patent application Ser. No. 12/127,544 and may similarly be used with the elements of system 20. - In the system configuration shown in
FIG. 1 ,sensors circuitry 36. The processing circuitry processes the signals to find location and orientation coordinates of the sensors, and hence ofantenna 32 andtransducer 42, in a common coordinate frame. Based on these coordinates, processingcircuitry 36 registers the ultrasonic images formed bytransducer 24 with the radar images formed byantenna 32. The processing circuitry finds the location of the stent in the radar image, and may also estimate its orientation. On this basis, the circuitry guidesoperator 22 to aimtransducer 24 toward the stent along the stent axis, i.e., along the direction of blood flow, in order to maximize the Doppler component in the ultrasound signals. For this purpose, the processing circuitry drives aguidance display 44, which indicates to the operator how to aim the ultrasound transducer toward the target. - In an alternative embodiment (not shown in the figures),
ultrasound transducer 24 may be held and manipulated by a robot arm, which is guided automatically by processing circuitry to aim the transducer in the desired direction. - Although
FIG. 1 shows a particular type of antenna and mode of coupling the antenna to the patient's body, other antenna types and configurations may also be used for the purposes described herein. For example, the antenna may mounted in a cushion below the patient's back, in a wearable element that fits over the patient's body, or in any other suitable mount. Some alternative configurations of this sort are shown in the above-mentioned U.S. patent application Ser. No. 12/127,544. -
FIG. 2 is a block diagram that schematically shows key elements of system 20, and particularly of processingcircuitry 36, in accordance with an embodiment of the present invention. Some of these elements are described in greater detail hereinbelow.Antenna 32 is driven by and outputs signals to afeature detection subsystem 50. The antenna typically comprises an array ofantenna elements 48, which are connected to a switchingmatrix 54 in afront end 52 ofsubsystem 50. The switching matrix selects different sets of the antennas to transmit and receive signals at different, respective times and frequencies, in a predetermined temporal pattern. Typically, the sets comprise pairs of antennas—one transmitting and one receiving—although other groupings may also be used. The pattern of antenna control is described in detail hereinbelow. - A
driver circuit 58 generates signals, at multiple different frequencies, for exciting the transmitting antennas and demodulates the signals received by the receiving antennas. Typically, the signals are in the range of about 400 MHz to about 4 GHz, although higher and lower frequencies outside this range may also be used. Asignal conditioning unit 56 between the driver circuit and switchingmatrix 54 amplifies the outgoing and the incoming signals and also cancels background components in the received signals. This functionality is also described below. -
Front end 52 outputs the demodulated received signals (as intermediate-frequency or baseband signals) to a digitaldata acquisition unit 60, which samples and digitizes the signals.Unit 60 typically comprises a high-resolution analog/digital converter, such as a 14-bit converter, with suitable sampling circuits as are known in the art. - A target detection, measurement and
tracking unit 62 receives and processes the digital samples.Unit 62, as described in detail hereinbelow, processes the sampled signals in order to generate a 3D radar image of the interior of the chest ofpatient 26. Within this image, elements having a dielectric constant that is different from that of the surrounding tissue, such as a metal stent in a coronary artery, stand out. On this basis,unit 62 identifies and measures the location coordinates of the stent relative toantenna 32. - Since the heart is in constant motion,
unit 62 may also track and model the motion of the stent in order to more precisely guideultrasound transducer 24. The direction of motion of the stent during the heart cycle also gives an indication of the direction of the stent axis (along which the ultrasound transducer should be aimed): Since the axis of the stent is oriented along the coronary artery in which the stent is implanted, and the coronary artery runs along the heart wall, the stent axis will typically be perpendicular to the direction of motion of the heart wall, and hence to the axis of motion of the stent in the radar image. As noted above,operator 22 is guided to aimultrasound transducer 24 toward the stent in a direction along, or at least close to, the stent axis. - Although the present embodiment relates specifically to identification and tracking of a stent, the techniques and circuits that are described here may be used, by the same token, in locating and tracking other features in the coronary blood vessels, such as calcifications, as well as features elsewhere in the body.
- A
tracking unit 64 communicates with trackingtransmitter 38 and receives position signals fromposition sensors ultrasound transducer 24 andantenna 32 in the frame of reference oftransmitter 38. The tracking unit may be a commercially-available device, such as in the above-mentioned FASTRAK system. - A
guidance processor 66 receives the position (location and orientation) coordinates from trackingunit 64 and the position coordinates of the stent fromfeature detection subsystem 50.Guidance processor 66 registers the coordinates of the stent in the coordinate frame of the tracking unit or, equivalently, registers the coordinates ofultrasound transducer 24 in the coordinate frame ofantenna 32, in which the stent coordinates have been found. The guidance processor is then able to compute the geometrical skew and offset between the present viewing axis of the ultrasound transducer and the desired viewing axis, which will intercept the stent along (or close to) the stent axis. Based on the computed skew and offset, the guidance processor may driveguidance display 44 to showoperator 22 the required correction. For this purpose, the guidance display may show, for example, target crosshairs and directional arrows, or any other suitable sort of directional indication. Alternatively,console 28 may use the computed skew in adjusting the Doppler velocity readings to account for the angle of measurement relative to the flow. -
Processing circuitry 36 typically comprises a combination of dedicated hardware circuits (such as infront end 52 and digital data acquisition unit 60) and programmable components. The front end circuits are described in detail hereinbelow. Target detection, measurement andtracking unit 62 andguidance processor 66 typically comprise programmable processors, such as a general-purpose microprocessor or a digital signal processor, which are programmed in software to carry out the functions that are described herein. Alternatively or additionally, these elements ofcircuitry 36 may comprise dedicated or programmable digital logic units such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). Althoughunits processor 66 are shown, for the sake of conceptual clarity, as separate functional blocks, in practice at least some of the functions of these different blocks may be carried out by a single processor. Alternatively, the functions of a given block may be divided up among two or more separate processors. -
FIG. 3 is a schematic, pictorial illustration ofantenna 32, in accordance with an embodiment of the present invention.Antenna 32 is a planar ultra-wideband, unidirectional antenna, comprising an array ofantenna elements 48. The antenna is designed for high-permittivity surroundings, enabling transmission and reception of ultra-wideband signals to and from the human body with minimal loss. In the pictured embodiment, the antenna comprises twelveantenna elements 48, which are spread in a rectangular plane to allow Cartesian acquisition of an image. Alternatively, the antenna may comprise a larger or smaller number of antenna elements, in a rectangular or non-rectangular array. - Each
antenna element 48 comprises a planar element comprising aconductive radiator 70, which is printed on acircuit board 72. This circuit board serves as the front surface of antenna, which is brought into contact with the patient's body.Circuit board 72 comprises multipleconductive vias 74 surrounding eachradiator 70 for isolatingantenna elements 48 from one another. The antenna elements are enclosed from behind by acase 76. -
FIG. 4 is a schematic, exploded view of one ofantenna elements 48, in accordance with an embodiment of the present invention. Each antenna element is constructed as an ellipse-shaped slotted antenna, excited electrically at its center feed point.Circuit board 72 comprises a dielectric substrate, such as an FR4 laminate, with a component (front) side that includesradiator 70 and aground plane 80. The radiator shape is optimized with an elliptical template to maintain a low voltage standing wave ratio (VSWR), with high antenna gain and flatness at boresight. This flatness assures good coverage of the entire region of interest (ROI) in the patient's body with constant antenna gain. - The printed (rear) side of
board 72 includes anexcitation transmission line 82 feeding the center point ofradiator 70 through a conductive via.Transmission line 82 comprises a fifty-ohm microstrip, with a micro-miniature coaxial (MMCX) connector (not shown) for connecting tofront end 50. Alternatively, other types of radiator shapes and feed lines may be used. - A
conductive cavity 84 is attached to the component side ofboard 72 behind eachradiator 70 in order to reduce antenna reverberations from back-lobe scattering and to increase the overall gain. (Antenna element 48 as shown inFIG. 4 has a nominal gain of 7 dBi at boresight.)Cavity 84 comprises ahollow waveguide 86, with dimensions designed such that the cutoff frequency of the lowest propagating mode (TE10) in the waveguide is higher than the upper band frequency limit ofantenna 32, -
- wherein C0 is the speed of light, ∈r is the permittivity of the interior of the waveguide, and a is the largest transverse dimension of the waveguide. In the present example, with a frequency limit of 4 GHz, the depth of
waveguide 86 is 15 mm. The waveguide creates an imaginary characteristic impedance, causing back-lobe radiation fromradiator 70 to reflect from the cavity in phase with the back-lobe waves. This reflection enhances the external buffering of the antenna and attenuates non-TE and TM modes, and therefore reduces interference and noise. - Cross-coupling between
antenna elements 48 can cause interference, which reduces the dynamic range and may saturate the receiver circuits. This cross-coupling is reduced inantenna 32 by appropriately setting the distance between the antenna elements in the array and by surroundingradiators 70 withconductive vias 74, as noted above. The vias serve as an electric wall that prevents internal waves from traveling between elements. They also create a conductive continuity betweenground plane 80 on the component side ofboard 72 and the top conductive transverse plane ofwaveguide 86 located on the print side. -
Antenna 32 is sealed against liquids and gels, thus preventing unwanted materials from reaching the print side and cavities of the antenna elements.Case 76, includingcavities 84, can be constructed from a molded plastic with a suitable conducting coating. Additionally or alternatively, the antenna elements may be printed on the molded plastic after coating. Although switchingmatrix 54 is shown and described herein as a part ofprocessing circuitry 36, it may alternatively be incorporated intoantenna 32 or mounted adjacent to the antenna, thereby performing the switching alongside the patient and reducing the weight and rigidity of the cable from the antenna to controlunit 34. - Although
antenna 32 is shown here as a unitary assembly containingantenna elements 48, the antenna elements (of similar design to that shown inFIG. 4 ) may alternatively be used singly or as dual- or multi-element panels, which can be attached to different body locations. Multiple position sensors can be used to compute and register the respective positions of the antenna elements. In such embodiments, system 20 may be configured to measure and analyze both waves reflected from the region of interest of the body and waves transmitted through the region and scattered by the target. -
FIG. 5 is a block diagram that schematically shows details offeature detection subsystem 50, in accordance with an embodiment of the present invention. As noted earlier, switchingmatrix 54 connectsantenna elements 48 to the other circuits offront end 52. Each antenna element connects to a respective single-pole double-throw (SPDT)switch 90, which determines whether the switch is to transmit or to receive waves at any given time. The transmit antenna element is selected, from among the multiple antenna elements, by a transmitswitch 92, while the receive antenna element is selected by a receiveswitch 94. The switching matrix thus permits any pair of the antenna elements to be selected as the transmitter and receiver at any given time. -
Switching matrix 54 is designed for high isolation between channels, typically better than 40 dB over the entire frequency range ofantenna 32.Switches output control module 104 and allow fast (non-mechanical) switching. This fast switching is required in order to allow the entire waveform sequence of different antenna pairs and frequencies to be completed in a short frame time, as described hereinbelow. For this purpose,matrix 54 is typically configured to achieve a switching time of less than 1 μs. -
Driver circuit 58 comprises abroadband signal generator 98, which generates the RF excitation waveform to drive the transmitting antenna elements, and areceiver 114, which receives and demodulates the signals generated by the receiving antenna elements.Signal generator 98 andreceiver 114 are both synchronized and sweep their frequencies according to a predefined frequency plan, which is shown inFIG. 6 , based on a sharedlocal oscillator 96. The frequency plan specifies the frequencies and power levels to be generated by the signal generator, in synchronization with an external trigger. The driving waveform enteringsignal conditioning unit 56 fromsignal generator 98 is sampled by abroadband coupler 100, amplified by apower amplifier 102 according to the required transmit power level, and transferred to switchingmatrix 54. -
Receiver 114 is a tuned super-heterodyne receiver, which is able to adjust its bandwidth and gain according to the received signal. The receiver demodulates the received signals coherently, in synchronization withlocal oscillator 96, in order to extract both the amplitude and the phase of the signals. The complex ratio between the transmitted and received signals, as measured by detection, measurement andtracking unit 62 for each antenna pair at each selected frequency, indicates the frequency response along corresponding paths through the region of interest. This region includes the chest, thoracic cavity, beating heart and the stent itself. - Despite the measures described above for reducing coupling between
different antenna elements 48 inantenna 32, the signals received fromantenna 32 bysignal conditioning unit 56 may still include a strong background component due to the direct coupling between the transmitting and receiving antenna elements. This background component raises the noise level due to transmitter nonlinearity and impurities in the transmitted signal and can even causereceiver 114 to saturate. It is therefore desirable to reduce the level of the background component that reaches the receiver in order to enhance the dynamic range of the radar image. - For this purpose,
signal conditioning unit 56 comprises an amplitude and phase modulator, referred to here as anIQ modulator 108, which receives the sampled RF excitation waveform fromcoupler 100. The IQ modulator modifies the phase and amplitude of the sampled signal, under the control of an analogoutput control module 110, so as to generate an anti-phased signal matching the background component that is to be canceled. The amplitude and phase values ofIQ modulator 108 are periodically updated and are then kept constant per frequency and per channel until coupling values change significantly and need updating. In other words,IQ modulator 108 outputs a signal that is equal in amplitude to the background component but 180° out of phase. Acoupler 106 adds this anti-phased signal to the received signal from switchingmatrix 54 and thus cancels the background component without degrading the actual radar signal from the body. Anamplifier 112 amplifies the signal following background cancellation for input toreceiver 114. -
FIG. 6 is a timing diagram that schematically illustrates a temporal excitation pattern thatfront end 52 applies toantenna 32, in accordance with an embodiment of the present invention. The front end generates a sequence of frames 120. Each time a radar measurement is triggered (ten times per second, for example), the frame defines a sweep of the excitation signal both in frequency and over spatial channels (antenna pairs). Each frame 120 comprisesmultiple frequency sub-frames 122 according to the number of frequencies to be used in image reconstruction. In the example shown inFIG. 6 , there are 128 such sub-frames, each lasting 750 μs. The frequencies in this example, as noted above, span the range between 400 MHz and 4 GHz. - Each
sub-frame 122 begins with a settling time 126 (typically a few hundred microseconds) for locking the amplitude and phase ofsignal generator 98. Following this initial delay, switchingmatrix 54 selectsdifferent channels 124 in sequence. Each channel uses one transmitting antenna element and one receiving antenna element, up to a total of n channels (for example, one hundred such channels in the example shown inFIG. 6 , each open for 5 μs). During each channel period, detection, measurement andtracking unit 62 collects samples of the received signal fromreceiver 114 for subsequent use in multi-frequency/multi-channel radar image reconstruction. - In alternative embodiments (not shown in the figures), other sorts of channel configurations may be used. For example, in monostatic configurations, a selected antenna element may serve as both transmitter and receiver, as opposed to bistatic or multistatic configurations, in which each antenna either transmits or receives. As another option, antenna elements may simply transmit and receive broadband RF pulses, rather than multiple narrowband pulses as in the embodiment described above.
- Based on the collected samples of the received signals, detection, measurement and
tracking unit 62 detects small reflecting volumes within the region of interest (ROI) in the patient's body. As noted above, the corresponding reflections arise at the boundaries of media having different dielectric properties. The information provided by coherent detection of the signals over the broad range of frequencies covered in each frame is equivalent mathematically to the temporal information that would be provided by reflection of a single short pulse. The locations of the reflectors may be found by integrating over the propagation paths of the reflected waves, using an inverse spherical Radon transformation, for example. - In an embodiment of the present invention, detection, measurement and
tracking unit 62 implements a first-order approximation of the inverse spherical Radon transform: For each voxel (x, y, z) in the ROI and for each frequency f and pair of antenna elements, a complex weight W(x,y,z,f,pair) is pre-calculated, either using an empirical calibration procedure or mathematical modeling. The weight is, in effect, the normalized complex amplitude (with conjugated phase) of the reflection that would be received at the receiving antenna in the pair from a point object at location (x,y,z) when irradiated by the transmitting antenna with a wave of frequency f. Because the body tissue through which the waves propagate is inhomogeneous, the weights may be adjusted, either empirically or by model calculation, to account for the specific tissue layers (skin, fat, muscle, lungs, etc.) through which the waves pass. - The set of weights thus derived defines a sort of matched filter. Detection, measurement and
tracking unit 62 applies this filter to the matrix of complex signals Sig(f,pair) that it receives in any given frame in order to compute the reflection intensity V for each voxel, as a weighted sum over the received signals: -
- The inventors have found that this simplified approximation of the inverse spherical Radon transform is both robust and computationally efficient.
-
FIG. 7 is a flow chart that schematically illustrates a method for measuring blood flow through a stent, in accordance with an embodiment of the present invention. The method is described hereinbelow, for the sake of clarity, with reference to the elements of system 20 that have been described above, but the same techniques may similarly be implemented in other system configurations. Furthermore, the elements of this method that relate to locating the stent in the body ofpatient 26 may likewise be applied, mutatis mutandis, for locating other features, both natural and artificial, in the coronary blood vessels, as well as elsewhere in the body. -
Front end 52drives antenna 32 to emit and receive RF waves over multiple frequencies and spatial channels (antenna pairs), at ascanning step 130, as described above. Detection, measurement andtracking unit 62 collects samples of the received signals and applies the weights defined in equation (1) to transform the signal values to voxel intensities, at animage reconstruction step 132. To improve the clarity of the image, the processing circuitry may apply additional image processing operations, such as subtracting the mean voxel value from all voxels in the image. The mean value may be smoothed over multiple successive images using a recursive filter.Unit 62 then identifies the coordinates of the target feature, i.e., the stent or another strong reflector, in the 3D image, at atarget identification step 134. - Features in the coronary arteries (or elsewhere in the heart), such as the stent, move regularly with the heart rhythm, as well as with chest movement due to respiration. In order to guide the ultrasound transducer, detection, measurement and
tracking unit 62 tracks the motion of the target in the successive images, at atarget tracking step 136. For example,unit 62 may apply a Kalman filter, as is known in the art, to estimate the motion trajectory of the target. -
Guidance processor 66 registers the coordinates ofultrasound transducer 24 withantenna 32, at a coordinateregistration step 138. The processor uses the position coordinates provided byposition sensors step 132. -
Guidance processor 66drives guidance display 44 to guideoperator 22 in aiming the ultrasound beam toward the target, at an aimingstep 140. It could be possible but would probably be impractical for a human operator, to moveultrasound transducer 24 continually back and forth in synchronism with the motion of the heart. (Such tracking could be feasible for a robot driven by the processing circuitry.) To alleviate this difficulty, the guidance processor selects a single location within the trajectory of motion found atstep 136 and guides the operator to aim at the selected location.Console 28 measures the flow through the stent at this location, at aflow measurement step 142, and thus provides an indication of the extent of any restenosis. - To select the target location at
step 140,guidance processor 66 may, for example, find the center of mass of the trajectory found atstep 136, and then choose a point that is displaced from the center toward the end of the trajectory that has the greater dwell time, which is the diastolic end. Blood flow through the coronary arteries occurs mainly during diastole, so that the diastolic end of the trajectory will give the strongest Doppler signal. Furthermore, aiming the ultrasound transducer toward the end of the trajectory with the greater dwell permits the ultrasonic beam to capture the stent for a longer part of each heart cycle and thus improves the signal/noise ratio. - It will be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.
Claims (24)
1-58. (canceled)
59. A radio-frequency (RF) monitoring and/or diagnostic apparatus, comprising:
a planar antenna configured to direct RF electromagnetic waves into the body of a patient and to generate signals responsively to the waves that are scattered from within the body, wherein a first surface of the antenna comprises a printed circuit board; and
processing circuitry configured to process the signals so as to determine a feature in the body responsively to a difference in a dielectric constant of the feature relative to surrounding tissue;
wherein, the antenna is configured to be positioned in close proximity to a surface of the body of the patient.
60. The apparatus of claim 59 , wherein close proximity to a surface of the body of the patient comprises the antenna being in contact with the skin of the patient.
61. The apparatus of claim 59 , further comprising a first material configured for arrangement between the body of the patient and the antenna.
62. The apparatus of claim 61 , wherein the first material comprises at least one of an adhesive, a gel, and apparel.
63. The apparatus of claim 59 , wherein determining the feature in the body comprises identifying and tracking a movement of the feature in the body.
64. The apparatus of claim 63 , wherein tracking the movement of the feature in the body includes imaging the feature and estimating a trajectory of the feature based on analysis of the image of the feature.
65. The apparatus of claim 59 , wherein the feature comprises a tissue in the body.
66. The apparatus of claim 59 , wherein the RF electromagnetic waves are in a frequency range of from about 400 MHz to about 4 GHz.
67. A radio-frequency (RF) monitoring and/or diagnostic apparatus comprising:
a planar antenna configured to direct RF electromagnetic waves into the body of a patient and to generate signals responsively to the waves that are scattered from within the body, wherein a first surface of the antenna comprises a printed circuit board;
processing circuitry configured to process the signals so as to determine a feature in the body responsively to a difference in a dielectric constant of the feature relative to surrounding tissue; and
a first material configured for arrangement between the antenna and the skin of the patient during use.
68. The apparatus of claim 67 , wherein the first material comprises at least one of an adhesive, a gel and apparel.
69. The apparatus of claim 67 , wherein the first material is configured so as to substantially affix the antenna in close proximity to the skin of the body.
70. The apparatus of claim 67 , further comprising a cavity proximate the antenna and configured to at least increase overall gain of the signals.
71. The apparatus of claim 70 , wherein the cavity comprises a waveguide.
72. The apparatus of claim 71 , wherein the waveguide includes dimensions configured such that a cutoff frequency of the lowest propagating mode in the waveguide exceeds an upper band frequency limit of the antenna.
73. The apparatus of claim 67 , further comprising a case for sealing the planar antenna against the first material and/or a liquid.
74. The apparatus of claim 67 , wherein the RF electromagnetic waves are in a frequency range of from about 400 MHz to about 4 GHz.
75. A radio-frequency (RF) monitoring and/or diagnostic apparatus comprising:
a planar antenna configured to direct RF electromagnetic waves into the body of a patient and to generate signals responsively to the waves that are scattered from within the body, wherein a first surface of the antenna comprises a printed circuit board;
processing circuitry configured to process the signals so as to determine a feature in the body responsively to a difference in a dielectric constant of the feature relative to surrounding tissue; and
a wearable element comprising at least one of the planar antenna and the processing circuitry, the wearable element configured to abut skin of the body of the patient.
76. The apparatus of claim 75 , wherein the planar antenna is a multi-element antenna, and further comprising a switching matrix configured to switch elements of the multi-element antenna between a transmitter and a receiver.
77. The apparatus of claim 75 , wherein determining a feature in the body comprises identifying and tracking a movement of the feature in the body.
78. The apparatus of claim 75 , wherein tracking the movement of the feature in the body includes imaging the feature and estimating a trajectory of the feature based on analysis of the image of the feature.
79. The apparatus of claim 75 , wherein the planar antenna includes a plurality of antenna elements, the plurality of antenna elements positioned about the body of the patient such that a first antenna element receives reflected waves and a second antenna element receives the scattered waves.
80. The apparatus of claim 79 , further comprising one or more position sensors configured to determine respective positions of the plurality of antenna elements.
81. The apparatus of claim 75 , wherein the RF electromagnetic waves are in a frequency range of from about 400 MHz to about 4 GHz.
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/996,145 US20160198976A1 (en) | 2008-05-27 | 2016-01-14 | Locating features in the heart using radio frequency imaging |
US15/206,021 US10588599B2 (en) | 2008-05-27 | 2016-07-08 | Methods and systems for determining fluid content of tissue |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US12/127,544 US8352015B2 (en) | 2008-05-27 | 2008-05-27 | Location tracking of a metallic object in a living body using a radar detector and guiding an ultrasound probe to direct ultrasound waves at the location |
PCT/IB2009/055438 WO2011067623A1 (en) | 2009-12-01 | 2009-12-01 | Locating features in the heart using radio frequency imaging |
US201213513396A | 2012-09-12 | 2012-09-12 | |
US14/996,145 US20160198976A1 (en) | 2008-05-27 | 2016-01-14 | Locating features in the heart using radio frequency imaging |
Related Parent Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/513,396 Continuation US9265438B2 (en) | 2008-05-27 | 2009-12-01 | Locating features in the heart using radio frequency imaging |
PCT/IB2009/055438 Continuation WO2011067623A1 (en) | 2008-05-27 | 2009-12-01 | Locating features in the heart using radio frequency imaging |
Related Child Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US12/127,544 Continuation US8352015B2 (en) | 2008-05-27 | 2008-05-27 | Location tracking of a metallic object in a living body using a radar detector and guiding an ultrasound probe to direct ultrasound waves at the location |
US15/206,021 Continuation US10588599B2 (en) | 2008-05-27 | 2016-07-08 | Methods and systems for determining fluid content of tissue |
Publications (1)
Publication Number | Publication Date |
---|---|
US20160198976A1 true US20160198976A1 (en) | 2016-07-14 |
Family
ID=44069436
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/513,396 Active 2031-08-23 US9265438B2 (en) | 2008-05-27 | 2009-12-01 | Locating features in the heart using radio frequency imaging |
US14/996,145 Abandoned US20160198976A1 (en) | 2008-05-27 | 2016-01-14 | Locating features in the heart using radio frequency imaging |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/513,396 Active 2031-08-23 US9265438B2 (en) | 2008-05-27 | 2009-12-01 | Locating features in the heart using radio frequency imaging |
Country Status (5)
Country | Link |
---|---|
US (2) | US9265438B2 (en) |
EP (1) | EP2506762B1 (en) |
JP (1) | JP5975879B2 (en) |
CA (1) | CA2782499A1 (en) |
WO (1) | WO2011067623A1 (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10136833B2 (en) | 2010-07-21 | 2018-11-27 | Zoll Medical Israel, Ltd. | Implantable radio-frequency sensor |
US10548485B2 (en) | 2015-01-12 | 2020-02-04 | Zoll Medical Israel Ltd. | Systems, apparatuses and methods for radio frequency-based attachment sensing |
US10588599B2 (en) | 2008-05-27 | 2020-03-17 | Zoll Medical Israel Ltd. | Methods and systems for determining fluid content of tissue |
US10680324B2 (en) | 2013-10-29 | 2020-06-09 | Zoll Medical Israel Ltd. | Antenna systems and devices and methods of manufacture thereof |
US11013420B2 (en) | 2014-02-05 | 2021-05-25 | Zoll Medical Israel Ltd. | Systems, apparatuses and methods for determining blood pressure |
US11020002B2 (en) | 2017-08-10 | 2021-06-01 | Zoll Medical Israel Ltd. | Systems, devices and methods for physiological monitoring of patients |
US11259715B2 (en) | 2014-09-08 | 2022-03-01 | Zoll Medical Israel Ltd. | Monitoring and diagnostics systems and methods |
Families Citing this family (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7047058B1 (en) | 2001-02-06 | 2006-05-16 | Medrad, Inc. | Apparatuses, systems and methods for extravasation detection |
US9265438B2 (en) | 2008-05-27 | 2016-02-23 | Kyma Medical Technologies Ltd. | Locating features in the heart using radio frequency imaging |
US11234608B2 (en) | 2011-09-02 | 2022-02-01 | Battelle Memorial Institute | Extravasation and infiltration detection device with fluid guide provided on a substrate of the detection device to adjust fluid rate based on detection signal |
DE102011083408A1 (en) * | 2011-09-26 | 2013-03-28 | Siemens Aktiengesellschaft | An imaging method and apparatus for displaying vessels or organs in an examination area of a patient |
US10413251B2 (en) | 2012-10-07 | 2019-09-17 | Rhythm Diagnostic Systems, Inc. | Wearable cardiac monitor |
TWI536959B (en) * | 2012-12-24 | 2016-06-11 | 財團法人工業技術研究院 | Aortic artery measuring probe, device and method of measuring diameter of aortic artery |
US20140180057A1 (en) * | 2012-12-24 | 2014-06-26 | Industrial Technology Research Institute | Aortic artery measuring probe, device and method of measuring diameter of aortic artery |
US9504404B1 (en) * | 2013-04-10 | 2016-11-29 | The University Of North Carolina At Charlotte | Antipodal vivaldi antenna array for biomedical imaging |
JP6214201B2 (en) * | 2013-05-02 | 2017-10-18 | キヤノン株式会社 | Image acquisition device |
WO2015101921A1 (en) * | 2013-12-30 | 2015-07-09 | University Of Manitoba | Imaging using gated elements |
WO2016005909A1 (en) | 2014-07-07 | 2016-01-14 | University Of Manitoba | Imaging using reconfigurable antennas |
DE102014220513A1 (en) * | 2014-09-30 | 2016-04-14 | Siemens Aktiengesellschaft | Multi-channel radar and multi-channel radar system |
US10856806B2 (en) * | 2015-02-12 | 2020-12-08 | University Of Hawaii | Lung water content measurement system and calibration method |
US10231644B2 (en) * | 2015-06-12 | 2019-03-19 | St Reproductive Technologies Llc | Calf bolus |
ES2729990T3 (en) * | 2016-01-20 | 2019-11-07 | Univ Pompeu Fabra | Medical system and device based on microwave technology for disease prevention and diagnosis |
US9869641B2 (en) | 2016-04-08 | 2018-01-16 | Ellumen, Inc. | Microwave imaging device |
US10976428B2 (en) * | 2017-02-14 | 2021-04-13 | The Trustees Of The Stevens Institute Of Technology | Synthetic ultra-wideband millimeter-wave imaging for tissue diagnostics |
US10128894B1 (en) * | 2017-05-09 | 2018-11-13 | Analog Devices Global | Active antenna calibration |
JP2022546991A (en) | 2019-08-28 | 2022-11-10 | アールディーエス | Vital signs or health monitoring system and method |
DE102020123169A1 (en) | 2020-09-04 | 2022-03-10 | Technische Universität Dresden, Körperschaft des öffentlichen Rechts | ENDOSCOPE DEVICE AND METHOD OF OPERATING THE SAME |
US11582511B2 (en) | 2021-03-15 | 2023-02-14 | Qualcomm Incorporated | Radio frequency sensing in a television environment |
TWI771103B (en) * | 2021-07-14 | 2022-07-11 | 立積電子股份有限公司 | Radar apparatus and signal receiving method thereof |
Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5829437A (en) * | 1994-07-01 | 1998-11-03 | Interstitial, Inc. | Microwave method and system to detect and locate cancers in heterogenous tissues |
US5841288A (en) * | 1996-02-12 | 1998-11-24 | Microwave Imaging System Technologies, Inc. | Two-dimensional microwave imaging apparatus and methods |
US6161036A (en) * | 1997-12-25 | 2000-12-12 | Nihon Kohden Corporation | Biological signal transmission apparatus |
US20040077943A1 (en) * | 2002-04-05 | 2004-04-22 | Meaney Paul M. | Systems and methods for 3-D data acquisition for microwave imaging |
US20090281412A1 (en) * | 2007-12-18 | 2009-11-12 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | System, devices, and methods for detecting occlusions in a biological subject |
US20100076315A1 (en) * | 2006-09-29 | 2010-03-25 | Koninklijke Philips Electronics N. V. | Method and apparatus for hands-free ultrasound |
US20110040176A1 (en) * | 2008-02-19 | 2011-02-17 | Helmholtz Zentrum Muenchen Deutsches Forschungszentrum fur Gesundheit und | Method and device for near-field dual-wave modality imaging |
Family Cites Families (126)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4240445A (en) | 1978-10-23 | 1980-12-23 | University Of Utah | Electromagnetic energy coupler/receiver apparatus and method |
FI58719C (en) | 1979-06-01 | 1981-04-10 | Instrumentarium Oy | DIAGNOSTISERINGSANORDNING FOER BROESTKANCER |
US4557272A (en) | 1980-03-31 | 1985-12-10 | Microwave Associates, Inc. | Microwave endoscope detection and treatment system |
US4344440A (en) | 1980-04-01 | 1982-08-17 | Trygve Aaby | Microprobe for monitoring biophysical phenomena associated with cardiac and neural activity |
US4986870A (en) | 1984-03-09 | 1991-01-22 | R.W.Q., Inc. | Apparatus for laminating multilayered printed circuit boards having both rigid and flexible portions |
US4632128A (en) | 1985-06-17 | 1986-12-30 | Rca Corporation | Antenna apparatus for scanning hyperthermia |
DE3623711A1 (en) | 1985-07-12 | 1987-01-15 | Med & Tech Handels Gmbh | Device for the determination of properties, variations and changes of the human or animal body |
US4640280A (en) | 1985-08-12 | 1987-02-03 | Rca Corporation | Microwave hyperthermia with dielectric lens focusing |
US4774961A (en) | 1985-11-07 | 1988-10-04 | M/A Com, Inc. | Multiple antennae breast screening system |
US4926868A (en) | 1987-04-15 | 1990-05-22 | Larsen Lawrence E | Method and apparatus for cardiac hemodynamic monitor |
US4825880A (en) | 1987-06-19 | 1989-05-02 | The Regents Of The University Of California | Implantable helical coil microwave antenna |
US4958638A (en) | 1988-06-30 | 1990-09-25 | Georgia Tech Research Corporation | Non-contact vital signs monitor |
US5003622A (en) | 1989-09-26 | 1991-03-26 | Astec International Limited | Printed circuit transformer |
US5404877A (en) | 1993-06-04 | 1995-04-11 | Telectronics Pacing Systems, Inc. | Leadless implantable sensor assembly and a cardiac emergency warning alarm |
JPH07136146A (en) * | 1993-06-24 | 1995-05-30 | Toshiba Corp | Mri apparatus |
US5394882A (en) | 1993-07-21 | 1995-03-07 | Respironics, Inc. | Physiological monitoring system |
US5549650A (en) | 1994-06-13 | 1996-08-27 | Pacesetter, Inc. | System and method for providing hemodynamically optimal pacing therapy |
US5704355A (en) | 1994-07-01 | 1998-01-06 | Bridges; Jack E. | Non-invasive system for breast cancer detection |
EP0694282B1 (en) * | 1994-07-01 | 2004-01-02 | Interstitial, LLC | Breast cancer detection and imaging by electromagnetic millimeter waves |
US5573012A (en) | 1994-08-09 | 1996-11-12 | The Regents Of The University Of California | Body monitoring and imaging apparatus and method |
US5540727A (en) | 1994-11-15 | 1996-07-30 | Cardiac Pacemakers, Inc. | Method and apparatus to automatically optimize the pacing mode and pacing cycle parameters of a dual chamber pacemaker |
US6019724A (en) | 1995-02-22 | 2000-02-01 | Gronningsaeter; Aage | Method for ultrasound guidance during clinical procedures |
US5668555A (en) * | 1995-09-01 | 1997-09-16 | Starr; Jon E. | Imaging system and apparatus |
US6093141A (en) | 1997-07-17 | 2000-07-25 | Hadasit Medical Research And Development Company Ltd. | Stereotactic radiotreatment and prevention |
US5967986A (en) | 1997-11-25 | 1999-10-19 | Vascusense, Inc. | Endoluminal implant with fluid flow sensing capability |
KR100285779B1 (en) * | 1997-12-10 | 2001-04-16 | 윤종용 | Base station antennas for mobile communications |
US6064903A (en) | 1997-12-29 | 2000-05-16 | Spectra Research, Inc. | Electromagnetic detection of an embedded dielectric region within an ambient dielectric region |
IL122839A0 (en) * | 1997-12-31 | 1998-08-16 | Ultra Guide Ltd | Calibration method and apparatus for calibrating position sensors on scanning transducers |
US6755856B2 (en) | 1998-09-05 | 2004-06-29 | Abbott Laboratories Vascular Enterprises Limited | Methods and apparatus for stenting comprising enhanced embolic protection, coupled with improved protection against restenosis and thrombus formation |
US6233479B1 (en) | 1998-09-15 | 2001-05-15 | The Regents Of The University Of California | Microwave hematoma detector |
US6330479B1 (en) | 1998-12-07 | 2001-12-11 | The Regents Of The University Of California | Microwave garment for heating and/or monitoring tissue |
US6193669B1 (en) | 1998-12-11 | 2001-02-27 | Florence Medical Ltd. | System and method for detecting, localizing, and characterizing occlusions, stent positioning, dissections and aneurysms in a vessel |
US6454711B1 (en) | 1999-04-23 | 2002-09-24 | The Regents Of The University Of California | Microwave hemorrhagic stroke detector |
CN1199536C (en) | 1999-10-26 | 2005-04-27 | 伊比登株式会社 | Multilayer printed wiring board and method of producing multilayer printed wiring board |
US6480733B1 (en) | 1999-11-10 | 2002-11-12 | Pacesetter, Inc. | Method for monitoring heart failure |
EP2324761A3 (en) | 2000-04-17 | 2014-06-18 | Adidas AG | Systems and methods for ambulatory monitoring of physiological signals |
US6526318B1 (en) | 2000-06-16 | 2003-02-25 | Mehdi M. Ansarinia | Stimulation method for the sphenopalatine ganglia, sphenopalatine nerve, or vidian nerve for treatment of medical conditions |
AU2001288417B2 (en) * | 2000-08-25 | 2004-07-22 | The Cleveland Clinic Foundation | Apparatus and method for assessing loads on adjacent bones |
US20020045836A1 (en) | 2000-10-16 | 2002-04-18 | Dima Alkawwas | Operation of wireless biopotential monitoring system |
JP2002198723A (en) | 2000-11-02 | 2002-07-12 | Ace Technol Co Ltd | Wideband directional antenna |
US6592518B2 (en) | 2001-04-05 | 2003-07-15 | Kenergy, Inc. | Cardiac monitoring system and method with multiple implanted transponders |
EP1411829A4 (en) | 2001-07-06 | 2010-03-10 | Wisconsin Alumni Res Found | Space-time microwave imaging for cancer detection |
EP1834667B1 (en) | 2001-07-26 | 2017-08-23 | Bayer Healthcare LLC | Electromagnetic sensors for biological tissue applications |
EP1622502A2 (en) | 2001-07-26 | 2006-02-08 | Medrad, Inc. | Detection of fluids in tissue |
US7191000B2 (en) | 2001-07-31 | 2007-03-13 | Cardiac Pacemakers, Inc. | Cardiac rhythm management system for edema |
US7505811B2 (en) | 2001-11-19 | 2009-03-17 | Dune Medical Devices Ltd. | Method and apparatus for examining tissue for predefined target cells, particularly cancerous cells, and a probe useful in such method and apparatus |
US6729336B2 (en) * | 2001-11-27 | 2004-05-04 | Pearl Technology Holdings, Llc | In-stent restenosis detection device |
US6730033B2 (en) | 2002-05-16 | 2004-05-04 | Siemens Medical Systems, Inc. | Two dimensional array and methods for imaging in three dimensions |
JP2003347787A (en) | 2002-05-23 | 2003-12-05 | Shin Etsu Chem Co Ltd | Electromagnetic wave absorbing composition |
US8892189B2 (en) | 2002-05-30 | 2014-11-18 | Alcatel Lucent | Apparatus and method for heart size measurement using microwave doppler radar |
WO2004013611A2 (en) | 2002-08-01 | 2004-02-12 | California Institute Of Technology | Remote-sensing method and device |
US7020508B2 (en) | 2002-08-22 | 2006-03-28 | Bodymedia, Inc. | Apparatus for detecting human physiological and contextual information |
US20040077952A1 (en) | 2002-10-21 | 2004-04-22 | Rafter Patrick G. | System and method for improved diagnostic image displays |
US7493154B2 (en) | 2002-10-23 | 2009-02-17 | Medtronic, Inc. | Methods and apparatus for locating body vessels and occlusions in body vessels |
US7697972B2 (en) | 2002-11-19 | 2010-04-13 | Medtronic Navigation, Inc. | Navigation system for cardiac therapies |
US7267651B2 (en) | 2003-04-25 | 2007-09-11 | Board Of Control Of Michigan Technological Univ. | Method and apparatus for blood flow measurement using millimeter wave band |
US7130681B2 (en) | 2003-05-09 | 2006-10-31 | Medtronic, Inc. | Use of accelerometer signal to augment ventricular arrhythmia detection |
EP1633276A2 (en) | 2003-05-29 | 2006-03-15 | Secor Medical, LLC | Filament based prosthesis |
US6932776B2 (en) | 2003-06-02 | 2005-08-23 | Meridian Medicalssystems, Llc | Method and apparatus for detecting and treating vulnerable plaques |
US20040249257A1 (en) | 2003-06-04 | 2004-12-09 | Tupin Joe Paul | Article of manufacture for extracting physiological data using ultra-wideband radar and improved signal processing techniques |
US7993460B2 (en) | 2003-06-30 | 2011-08-09 | Lam Research Corporation | Substrate support having dynamic temperature control |
US6940457B2 (en) | 2003-09-09 | 2005-09-06 | Center For Remote Sensing, Inc. | Multifrequency antenna with reduced rear radiation and reception |
US7454242B2 (en) | 2003-09-17 | 2008-11-18 | Elise Fear | Tissue sensing adaptive radar imaging for breast tumor detection |
US7280863B2 (en) | 2003-10-20 | 2007-10-09 | Magnetecs, Inc. | System and method for radar-assisted catheter guidance and control |
WO2005043100A2 (en) | 2003-10-24 | 2005-05-12 | Medrad, Inc. | Systems for detecting fluid changes and sensor devices therefor |
US7266407B2 (en) | 2003-11-17 | 2007-09-04 | University Of Florida Research Foundation, Inc. | Multi-frequency microwave-induced thermoacoustic imaging of biological tissue |
US7474918B2 (en) | 2004-03-24 | 2009-01-06 | Noninvasive Medical Technologies, Inc. | Thoracic impedance monitor and electrode array and method of use |
DE102004015859A1 (en) * | 2004-03-31 | 2005-10-20 | Siemens Ag | Method for generating magnetic resonance recordings of an examination object, dielectric element and use of the dielectric element |
US7210966B2 (en) | 2004-07-12 | 2007-05-01 | Medtronic, Inc. | Multi-polar feedthrough array for analog communication with implantable medical device circuitry |
US20080097199A1 (en) * | 2004-08-20 | 2008-04-24 | David Mullen | Tissue Marking Devices and Systems |
CN101094611B (en) | 2005-01-04 | 2010-08-18 | 株式会社日立医药 | Ultrasonographic device |
GB0502651D0 (en) * | 2005-02-09 | 2005-03-16 | Univ Bristol | Methods and apparatus for measuring the internal structure of an object |
US7872605B2 (en) | 2005-03-15 | 2011-01-18 | Fractus, S.A. | Slotted ground-plane used as a slot antenna or used for a PIFA antenna |
US20070016032A1 (en) | 2005-04-05 | 2007-01-18 | Gerard Aknine | Microwave devices for treating biological samples and tissue and methods for imaging |
US20060265034A1 (en) | 2005-04-05 | 2006-11-23 | Ams Medical Sa | Microwave devices for treating biological samples and tissue and methods for using same |
US20090048500A1 (en) | 2005-04-20 | 2009-02-19 | Respimetrix, Inc. | Method for using a non-invasive cardiac and respiratory monitoring system |
JP2006319767A (en) * | 2005-05-13 | 2006-11-24 | Sony Corp | Flat antenna |
US7671784B2 (en) | 2005-05-31 | 2010-03-02 | L-3 Communications Cyterra Corporation | Computerized tomography using radar |
US7312742B2 (en) | 2005-05-31 | 2007-12-25 | L-3 Communications Security And Detection Systems, Inc. | Computerized tomography using radar |
US7638341B2 (en) | 2005-06-09 | 2009-12-29 | The Regents Of The University Of California | Volumetric induction phase shift detection system for determining tissue water content properties |
US8162837B2 (en) * | 2005-06-13 | 2012-04-24 | Spentech, Inc. | Medical doppler ultrasound system for locating and tracking blood flow |
WO2007010460A2 (en) | 2005-07-15 | 2007-01-25 | Koninklijke Philips Electronics N.V. | Apparatus for the detection of heart activity |
US7529398B2 (en) | 2005-08-09 | 2009-05-05 | Gil Zwirn | High resolution radio frequency medical imaging and therapy system |
JP4803529B2 (en) | 2005-08-31 | 2011-10-26 | 国立大学法人 長崎大学 | Mammography method using microwave and mammography apparatus |
US7760082B2 (en) | 2005-09-21 | 2010-07-20 | Chon Meng Wong | System and method for active monitoring and diagnostics of life signs using heartbeat waveform and body temperature remotely giving the user freedom to move within its vicinity without wires attachment, gel, or adhesives |
US8369950B2 (en) | 2005-10-28 | 2013-02-05 | Cardiac Pacemakers, Inc. | Implantable medical device with fractal antenna |
US8204586B2 (en) | 2005-11-22 | 2012-06-19 | Proteus Biomedical, Inc. | External continuous field tomography |
US7927288B2 (en) | 2006-01-20 | 2011-04-19 | The Regents Of The University Of Michigan | In situ tissue analysis device and method |
KR101414586B1 (en) * | 2006-03-06 | 2014-07-03 | 센시오텍 아이엔씨 | Ultra wideband monitoring systems and antennas |
US7844081B2 (en) | 2006-05-15 | 2010-11-30 | Battelle Memorial Institute | Imaging systems and methods for obtaining and using biometric information |
EP1860458A1 (en) | 2006-05-22 | 2007-11-28 | Interuniversitair Microelektronica Centrum | Detection of resonant tags by UWB radar |
US8562526B2 (en) | 2006-06-01 | 2013-10-22 | Resmed Sensor Technologies Limited | Apparatus, system, and method for monitoring physiological signs |
WO2008076464A2 (en) | 2006-06-21 | 2008-06-26 | Surgisense Corporation | Wireless medical telemetry system and methods using radio-frequency energized biosensors |
JP4622954B2 (en) | 2006-08-01 | 2011-02-02 | 株式会社デンソー | Line waveguide converter and wireless communication device |
US20080167566A1 (en) * | 2006-08-08 | 2008-07-10 | Kamil Unver | Systems and methods for determining systolic time intervals |
US7808434B2 (en) | 2006-08-09 | 2010-10-05 | Avx Corporation | Systems and methods for integrated antennae structures in multilayer organic-based printed circuit devices |
EP2068703A4 (en) | 2006-09-21 | 2011-07-20 | Noninvasive Medical Technologies Inc | Apparatus and method for non-invasive thoracic radio interrogation |
CA2664166A1 (en) | 2006-09-21 | 2008-03-27 | Noninvasive Medical Technologies, Inc. | Antenna for thoracic radio interrogation |
US7479790B2 (en) | 2006-11-09 | 2009-01-20 | The Boeing Company | Capacitive plate dielectrometer method and system for measuring dielectric properties |
US7612676B2 (en) | 2006-12-05 | 2009-11-03 | The Hong Kong University Of Science And Technology | RFID tag and antenna |
EP2101641A2 (en) | 2006-12-07 | 2009-09-23 | Philometron, Inc. | Platform for detection of tissue content and/or structural changes with closed-loop control in mammalian organisms |
JP4378378B2 (en) * | 2006-12-12 | 2009-12-02 | アルプス電気株式会社 | Antenna device |
US7792588B2 (en) | 2007-01-26 | 2010-09-07 | Medtronic, Inc. | Radio frequency transponder based implantable medical system |
RU2331894C1 (en) | 2007-02-14 | 2008-08-20 | Открытое акционерное общество Научно-производственная Компания "Высокие Технологии" | Method of dielectric properties measurement for material bodies and device for its implementation |
DE602007008821D1 (en) | 2007-03-02 | 2010-10-14 | Saab Ab | Hull integrated antenna |
US20080294036A1 (en) * | 2007-04-23 | 2008-11-27 | Device Evolutions, Llc | Surgical Metal Detection Apparatus and Methods |
WO2008148040A1 (en) | 2007-05-24 | 2008-12-04 | Lifewave, Inc. | System and method for non-invasive instantaneous and continuous measurement of cardiac chamber volume |
WO2009005912A2 (en) | 2007-05-30 | 2009-01-08 | Massachusetts Institute Of Technology | Notch antenna having a low profile stripline feed |
US7747302B2 (en) | 2007-08-08 | 2010-06-29 | Lifescan, Inc. | Method for integrating facilitated blood flow and blood analyte monitoring |
US20110160549A1 (en) | 2007-09-05 | 2011-06-30 | Saroka Amir | Method, system and apparatus for using electromagnetic radiation for monitoring a tissue of a user |
US20090076349A1 (en) | 2007-09-14 | 2009-03-19 | Corventis, Inc. | Adherent Multi-Sensor Device with Implantable Device Communication Capabilities |
GB0721694D0 (en) | 2007-11-05 | 2007-12-12 | Univ Bristol | Methods and apparatus for measuring the contents of a search volume |
US20090153412A1 (en) | 2007-12-18 | 2009-06-18 | Bing Chiang | Antenna slot windows for electronic device |
JP5550100B2 (en) | 2007-12-26 | 2014-07-16 | 日本電気株式会社 | Electromagnetic bandgap element, antenna and filter using the same |
EP2248274A4 (en) | 2008-02-01 | 2015-10-07 | Smith & Nephew Inc | System and method for communicating with an implant |
US8352015B2 (en) | 2008-05-27 | 2013-01-08 | Kyma Medical Technologies, Ltd. | Location tracking of a metallic object in a living body using a radar detector and guiding an ultrasound probe to direct ultrasound waves at the location |
US9265438B2 (en) | 2008-05-27 | 2016-02-23 | Kyma Medical Technologies Ltd. | Locating features in the heart using radio frequency imaging |
US8989837B2 (en) | 2009-12-01 | 2015-03-24 | Kyma Medical Technologies Ltd. | Methods and systems for determining fluid content of tissue |
WO2009152625A1 (en) | 2008-06-18 | 2009-12-23 | Solianis Holding Ag | Method and device for characterizing the effect of a skin treatment agent on skin |
US10667715B2 (en) | 2008-08-20 | 2020-06-02 | Sensible Medical Innovations Ltd. | Methods and devices of cardiac tissue monitoring and analysis |
US9002427B2 (en) | 2009-03-30 | 2015-04-07 | Lifewave Biomedical, Inc. | Apparatus and method for continuous noninvasive measurement of respiratory function and events |
JP2012525952A (en) | 2009-06-03 | 2012-10-25 | カーディアック ペースメイカーズ, インコーポレイテッド | System and method for monitoring cardiovascular pressure |
US8325094B2 (en) | 2009-06-17 | 2012-12-04 | Apple Inc. | Dielectric window antennas for electronic devices |
US9610450B2 (en) | 2010-07-30 | 2017-04-04 | Medtronics, Inc. | Antenna for an implantable medical device |
US8542151B2 (en) | 2010-10-21 | 2013-09-24 | Mediatek Inc. | Antenna module and antenna unit thereof |
US20120104103A1 (en) | 2010-10-29 | 2012-05-03 | Nxp B.V. | Integrated pcb uhf rfid matching network/antenna |
-
2009
- 2009-12-01 US US13/513,396 patent/US9265438B2/en active Active
- 2009-12-01 EP EP09851811.1A patent/EP2506762B1/en active Active
- 2009-12-01 JP JP2012541588A patent/JP5975879B2/en active Active
- 2009-12-01 CA CA2782499A patent/CA2782499A1/en not_active Abandoned
- 2009-12-01 WO PCT/IB2009/055438 patent/WO2011067623A1/en active Application Filing
-
2016
- 2016-01-14 US US14/996,145 patent/US20160198976A1/en not_active Abandoned
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5829437A (en) * | 1994-07-01 | 1998-11-03 | Interstitial, Inc. | Microwave method and system to detect and locate cancers in heterogenous tissues |
US5841288A (en) * | 1996-02-12 | 1998-11-24 | Microwave Imaging System Technologies, Inc. | Two-dimensional microwave imaging apparatus and methods |
US6161036A (en) * | 1997-12-25 | 2000-12-12 | Nihon Kohden Corporation | Biological signal transmission apparatus |
US20040077943A1 (en) * | 2002-04-05 | 2004-04-22 | Meaney Paul M. | Systems and methods for 3-D data acquisition for microwave imaging |
US20100076315A1 (en) * | 2006-09-29 | 2010-03-25 | Koninklijke Philips Electronics N. V. | Method and apparatus for hands-free ultrasound |
US20090281412A1 (en) * | 2007-12-18 | 2009-11-12 | Searete Llc, A Limited Liability Corporation Of The State Of Delaware | System, devices, and methods for detecting occlusions in a biological subject |
US20110040176A1 (en) * | 2008-02-19 | 2011-02-17 | Helmholtz Zentrum Muenchen Deutsches Forschungszentrum fur Gesundheit und | Method and device for near-field dual-wave modality imaging |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10588599B2 (en) | 2008-05-27 | 2020-03-17 | Zoll Medical Israel Ltd. | Methods and systems for determining fluid content of tissue |
US10660609B2 (en) | 2009-12-01 | 2020-05-26 | Zoll Medical Israel Ltd. | Methods and systems for determining fluid content of tissue |
US11471127B2 (en) | 2009-12-01 | 2022-10-18 | Zoll Medical Israel Ltd. | Methods and systems for determining fluid content of tissue |
US10136833B2 (en) | 2010-07-21 | 2018-11-27 | Zoll Medical Israel, Ltd. | Implantable radio-frequency sensor |
US10680324B2 (en) | 2013-10-29 | 2020-06-09 | Zoll Medical Israel Ltd. | Antenna systems and devices and methods of manufacture thereof |
US11539125B2 (en) | 2013-10-29 | 2022-12-27 | Zoll Medical Israel Ltd. | Antenna systems and devices, and methods of manufacture thereof |
US11108153B2 (en) | 2013-10-29 | 2021-08-31 | Zoll Medical Israel Ltd. | Antenna systems and devices and methods of manufacture thereof |
US11883136B2 (en) | 2014-02-05 | 2024-01-30 | Zoll Medical Israel Ltd. | Systems, apparatuses and methods for determining blood pressure |
US11013420B2 (en) | 2014-02-05 | 2021-05-25 | Zoll Medical Israel Ltd. | Systems, apparatuses and methods for determining blood pressure |
US11259715B2 (en) | 2014-09-08 | 2022-03-01 | Zoll Medical Israel Ltd. | Monitoring and diagnostics systems and methods |
US11241158B2 (en) | 2015-01-12 | 2022-02-08 | Zoll Medical Israel Ltd. | Systems, apparatuses and methods for radio frequency-based attachment sensing |
US10548485B2 (en) | 2015-01-12 | 2020-02-04 | Zoll Medical Israel Ltd. | Systems, apparatuses and methods for radio frequency-based attachment sensing |
US11020002B2 (en) | 2017-08-10 | 2021-06-01 | Zoll Medical Israel Ltd. | Systems, devices and methods for physiological monitoring of patients |
US11872012B2 (en) | 2017-08-10 | 2024-01-16 | Zoll Medical Israel Ltd. | Systems, devices and methods for physiological monitoring of patients |
Also Published As
Publication number | Publication date |
---|---|
CA2782499A1 (en) | 2011-06-09 |
JP5975879B2 (en) | 2016-08-23 |
WO2011067623A1 (en) | 2011-06-09 |
US9265438B2 (en) | 2016-02-23 |
EP2506762A4 (en) | 2013-07-24 |
EP2506762B1 (en) | 2019-03-06 |
EP2506762A1 (en) | 2012-10-10 |
US20120330151A1 (en) | 2012-12-27 |
JP2013512064A (en) | 2013-04-11 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9265438B2 (en) | Locating features in the heart using radio frequency imaging | |
EP2234539B1 (en) | Synthetic aperture radar system | |
US8784320B2 (en) | Ultrasound garment | |
US7647089B2 (en) | Surface identification using microwave signals for microwave-based detection of cancer | |
US7809427B2 (en) | Time domain inverse scattering techniques for use in microwave imaging | |
EP2506917B1 (en) | Microwave monitoring of heart function | |
Leib et al. | Vital signs monitoring with a UWB radar based on a correlation receiver | |
US20120289827A1 (en) | Multi-Modality Ultrasound and Radio Frequency Methodology for Imaging Tissue | |
US20200000366A1 (en) | In-body backscatter communication and localization | |
US10993619B2 (en) | Systems and methods for ultra-wideband (UWB) radar detection and tracking of tumors in real-time | |
US20120296204A1 (en) | Multi-Modality Ultrasound and Radio Frequency System for Imaging Tissue | |
US20210137406A1 (en) | Scanning device for living objects | |
JP2015045655A (en) | Locating features in heart using radio frequency imaging | |
EP2692287A1 (en) | Multi-modality ultrasound and radio frequency methodology for imaging tissue | |
Solimene et al. | An incoherent radar imaging system for medical applications | |
Alexopoulos et al. | Standoff tracking of medical interventional devices using non-contact microwave thermoacoustic detection | |
Dominic et al. | Evaluation of Imaging Algorithms for Medical Applications with a Multi-Channel Ultra-Wideband Radar System | |
Kromer et al. | Ultra-Wideband Microwave Radar for Medical Imaging Applications | |
Lazaro et al. | Weighted centroid method for breast tumor localization using an UWB radar | |
Zhang et al. | MANUAL MODEL BACKGROUND SUBTRACTION METHOD FOR RADAR-BASED BREAST CANCER DETECTION EXPERIMENT | |
Zhang et al. | A shape reconstruction method using ir-uwb by illuminating the target from multiple aspects | |
Fathy et al. | 8 Biomedical Applications of UWB Technology | |
Cheeseman et al. | Limited multi-static calibration technique without a phantom for the detection of breast cancer | |
Ünal et al. | Analysis of dispersive effects of breast phantom model on ultra wideband microwave imaging of breast cancer tumor | |
Dhieb et al. | UWB radar’s detection and measurement of human heart beating rate |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: KYMA MEDICAL TECHNOLOGIES LTD., ISRAEL Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:WEINSTEIN, URIEL;BERNSTEIN, ASSAF;COHEN, EYAL;AND OTHERS;REEL/FRAME:038175/0576 Effective date: 20120904 |
|
AS | Assignment |
Owner name: ZOLL MEDICAL ISRAEL LTD., ISRAEL Free format text: CHANGE OF NAME;ASSIGNOR:KYMA MEDICAL TECHNOLOGIES LTD.;REEL/FRAME:043260/0219 Effective date: 20161123 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |