WO2008062451A2

WO2008062451A2 - Echogenic surface for surgical instrument

Info

Publication number: WO2008062451A2
Application number: PCT/IN2007/000431
Authority: WO
Inventors: Gautam Allahbadia
Original assignee: Gautam Allahbadia
Priority date: 2006-09-07
Filing date: 2007-09-06
Publication date: 2008-05-29
Also published as: WO2008062451A3

Abstract

An echogenic surface surgical instrument, more particularly an echogenic surface surgical needle for use in ultrasonic imaging to facilitate real-time ultrasound imaging and monitoring of the needle during surgical procedures. At least a portion of a structural surface of the needle comprises grooves to entrap gas column.

Description

TITLE: ECHOGENIC SURFACE FOR SURGICAL INSTRUMENT

Technical Field of the Invention

In general there is provided an echogenic surgical instrument for use in ultrasonic imaging to facilitate real-time monitoring of the position and location of the surgical instrument during surgical procedures. More particularly, the invention relates to an echogenic surface needle covered with entrapped gas column for facilitating monitoring of the needle as it is positioned within the body of a patient.

Relevant Prior Art

During recent years ultrasonic imaging has become widely used and accepted in clinical and medical diagnosis, particularly in obstetrics, gynecology and urology. Physicians often use μltrasound to image a wide variety of medical abnormalities including malignant and non- malignant cysts and tumors and fetal status in uterus. In such applications it is often desirable for a physician to have an image of a surgical instrument which been positioned within the body of a patient Ultrasonic imaging is also used for real-time monitoring of surgical instrument, for example, needle location during medical procedures such as ovum pickup, ovarian puncture, embryo transfer, fetal blood sampling, amniocentesis, tissue aspiration biopsy and core biopsy. In recent developments, considerable efforts have been expended to significantly enhance the ultrasound image of a needle, at least its point or tip, to accurately locate its placement and advancement over real-time ultrasonic guidance by enhancing the acoustic reflection coefficient of the instruments/needles. Such measures not only are critical in guiding accurately in obtaining proper sampling, but also necessary to avoid puncturing or damaging of tissues.

In ultrasqnic imaging, Echogenicity is referred to relative, intrinsic or innate degree of extent that a surface reflects incident ultrasound wave energy directly back to sensor, which is proximal to the source or emitter. In theory, the degree of echogenicity is directly interdependent on two primary factors: (1) the density of the 'target' receiving and reflecting the sound energy, and (2) the elasticity of the 'target' being ultrasonically imaged. These^ two factors are, in fact, professed to be the essential factors why air and/or water in tissue or organs are more echogenic or alter the echogenicity. The same is applicable to dense metal, such as shaft of a needle.

US Patent No. 4,401,124 outlines some of the problems associated with monitoring the insertion and guidance of needles and other instruments. The patent teaches a proposed solution by providing, in an ultrasound pulse-echo imaging system, a diffracting grating disposed on the surface of the surgical instrument. The diffraction grating exemplified to have a specified distance between the depths of adjacent grooves, that distance being a function of various parameters including the center wavelength of the transducer and the angle between the incident beam and a line along the surface of the instrument and perpendiculars to the grooves. The reference also discloses other attempts directed toward monitoring the location of a surgical instrument, such as a needle, inside the body as well as discussing their drawbacks. Although system with its helical diffraction grating around the tip of the needle, along with other needles having similar rings, may provide some degree of signal reinforcement along the axis of incident energy, the overall image if far from ideal. Further, needles of this type typically exhibit a marked loss of resolution, as the needle is oriented away from an optimum angle relative to the incident ultrasound beam, which angle depends upon the particular ring parameters.

Another US Patent No. 5,201,314 refers about an echogenic material in which small pellets of other material is used to make a density difference from the surrounding tissues. Such material with different acoustic impedance is mixed with the material right in the extrusion process or blasted later on onto it. One problem with this approach is that the interface layer is generated during the extrusion process for forming a plastic device, or by soldering, or ion beam deposition, Which is inapplicable to many devices, and is expensive and difficult to control. Also the differences in acoustical properties between glass or metal aηd body cavities are not very large, so echogenicity is not greatly enhanced. Further, the described devices are not smooth since the echogenicity is produced either by indentations in the surface or the addition of metal or glass balls of diameter greater than the thickness of the interface layer. The presence of the particles complicates the manufacturing process, and may weaken the surface the device, which can lead to sloughing of particles, device failure, or instability of the desired effect.

Another US Patent No. 6,610,016 describes echogenic coating, which has a highly porous surface. Due to the porous nature of the surface, air is trapped in it to form a low-density material. This density difference makes application of such device difficult and unsuitable for medical procedures/use. There is still an essential need for accurate monitoring of a surgical instrument such as a needle inserted within the body of a patient, which does not require a specific angle of orientation for its efficiency, and is inexpensive to manufacture.

Summary of the Invention

In the view of above, there is provided a surgical instrument having an echogenic surface in use with ultrasonic imaging for enhancing real-time monitoring of the position and location of the surgical instrument. In comparison to conventionally known devices, the surgical instrument of the present invention preferably has relatively high practical echogenicity, useful in avoiding complications such as poor ultrasonic imaging during surgical procedures. In particularly, there is provided an echogenic surgical needle which is covered with the entrapped gas column to enable a physician to precisely needle position within body of a patient.

In accordance with various aspects of the present invention, there is provided an echogenic surface surgical needle for facilitating real-time imaging and monitoring of the needle position using conventionally ultrasonic imaging technology/system, where the needle is inserted and guided through the body of a patient for medical procedures such as ovum pickup, fetal blood sampling, amniocentesis or tissue aspiration biopsy.

In accordance with one of the embodiment, a specific structural surface portion of the needle is removed and grooved in specific pattern, which is coated with non-sagging material, converting groove into a gas column. Further aspects and advantages of the present invention will become apparent from the following description.

Brief Description of Drawings

The embodiments in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. However, like parts do not always have like reference numerals.

FlG.1 is an top view of virgin needle which no grooves, having a specific cut at the distal end which is well-known in the prior art. Ultrasonic beam (8) is incident on the needle, which is reflected (9) back. Because there is no specific treatment, there is no beam reflected in direction (19)

FIG.2 is an top view of needle having longitudinal grooves (10), covered with a thin transparent polymer (15).

FiG.3 is an top view of needle with circumferential groove (45). Ultrasound beam (40) is incident on the gas column, and beam is reflected in all directions (42). The needle is covered with a thin sheet (46) of biocompatible polymer.

Fig 4 represents the principle of working of ultrasound imaging technology. The incident beam (31) Is partly transmitted (33) and partly reflected (32).

Description of the Preferred Embodiments

For the purposes of promoting an understanding of the working principles of the invention, reference will be made to the embodiments illustrated in the drawings along with the detailed description. However, it will be appreciated that the detailed description refers to preferred embodiments of the present invention and that modifications of detail may be made within the scope of the invention. The standard ultrasonic imaging system employed in the medical field is based upon the pulse-echo method wherein pulses of ultrasonic energy are periodically generated by a sizable piezoelectric transducer. Each short pulse of ultrasonic energy is focused to a narrow beam to pass through the body of a patient wherein it eventually encounters the desired 'target' surface. A portion of the ultrasonic energy is reflected back from the target surface to the ultrasound senor for correlation and interpretation. FIG.1 represents a standard, virgin needle (1) made of an appropriate material such as stainless steei. Needle (1) has smooth outer surface (3) and bore (2), commonly use in the medical field. Needle (1 ) is more echogenic when it is at a right angle to incident ultrasonic beams (8). The majority of the reflected beams (9) are picked up by a sensor, located proximal to the source or emitter of incident beams (8). As shown in Fig 4, the incident beam (31) is partly reflected (32) and partly transmitted (33). The amount of beam reflected proportional to the ratio of the density difference D1/ D2. When needle (1) is oriented at an angle to the emitter and sensor, the density of direct echoes returned or reflected to the sensor, decreases. Although the density and elasticity of needle do not change, the echogenicity of needle (1) is significantly decreased as the introductory or advancement angle of the needle (1) is varied away from 9OG with respect to incident beams (8) there is no reflection in the direction (19). Referring FIG.2 and FIG. 3, needle are prepared in accordance with the preferred embodiment of the present invention. A virgin needle such as needle (1) shown in FIG. 1 is cut superficially into different shapes such as shown in FIG 2 and 3. FIG 2 shows superficial longitudinal grooves made on needle (10). However, the smooth surface (3) will show normal reflectance under ultrasound. The grooves (10) and (45) are covered with a thin polymeric material (15) and (46) respectively, which is essentially biocompatible. The material should be thin enough not to disturb the surrounding tissue while inserting such needle into the body cavity or there should be proper contours made to that effect. The material may be coated by dip coating or a thin sheet may be wrapped around the needle to create gas column. Dipping the grooved need\e into a high viscosity polymer solution containing tiny air bubbles can also create gas column. Due to high viscosity the polymer will not flow into the grooves creating gas columns. As shown in FIG 3, the grooves can be made circumferential. The advantage of this shape is that the needle can be seen under ultrasound from any direction. There are no black spots when used in this shape. Other shapes such as spiral grooves and dots can also be developed. As shown in Fig 3 due to the gas columh, the ultrasound wave (40) gets reflected in all directions (42). The advantage of this column is that the needle can be held in any desired direction, giving same echogenic reflection.

Alternative embodiment are contemplated where in the gas column can be made up of any gas or vacuum. The gas column may be created in the material of construction of the surgical instrument which and that would result in similar effect of enhancing the echogenecity. Also it is contemplated that where gas column is trapped by any means other than disclosed here the needle would have the same echogenic effect. The effective gas column dimension can be as small as 5 microns to as large as the circumference of the needle.

Claims

ClaimsWhat I claim is -

1. An echogenic surface surgical instrument for enhancing real-time imaging of the surgical instrument in use with an ultrasonic imaging system, comprising a surgical instrument wherein at least a portion of a structural surface of the instrument comprises of grooves, wherein the grooves are covered with a polymeric material to create one or more gas column.

2. An echogenic surface surgical instrument for enhancing real-time monitoring of the surgical instrument in use with an ultrasonic imaging system, comprising a surgical instrument wherein at least a portion of a structural surface of the instrument comprises of grooves, wherein the grooves are covered with a polymeric material to create one or more gas column.

3. An echogenic surface surgical instrument for enhancing real-time imaging of the surgical instrument in use with an ultrasonic imaging system, comprising a surgical needle wherein at least a portion of a structural surface of the needle comprises of grooves which is dipped into a polymer solution to create one or more gas column.

4. An echogenic surface surgical instrument for enhancing real-time monitoring of the surgical instrument in use with an ultrasonic imaging system, comprising a surgical needle wherein at least a portion of a structural surface of the needle comprises of grooves which is dipped into a polymer solution to create one or more gas column.

5. The surgical instrument according to claim 1 and 2, wherein the polymeric material is biocompatible.

6. The surgical instrument according to claim 3 and 4, wherein the polymer solution contains tiny air bubbles.

7. The surgical instrument according to claim 1, 2, 3 and 4, the surgical instrument is a surgical needle, ovum pick up needle, biopsy needle used for ultrasonic surgical or diagnostic intervention on the human body.

8. An echogenic surface surgical instrument for enhancing real-time imaging and monitoring of the surgical instrument in use with an ultrasonic imaging system, comprising a surgical instrument wherein the gas is trapped in the material used for making such instrument.