CN101545960B - Cylindrical surface coil and method and system for processing radio frequency signal for same - Google Patents
Cylindrical surface coil and method and system for processing radio frequency signal for same Download PDFInfo
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- CN101545960B CN101545960B CN2008100841393A CN200810084139A CN101545960B CN 101545960 B CN101545960 B CN 101545960B CN 2008100841393 A CN2008100841393 A CN 2008100841393A CN 200810084139 A CN200810084139 A CN 200810084139A CN 101545960 B CN101545960 B CN 101545960B
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Abstract
The invention provides a method for processing a radio frequency signal for a cylindrical surface coil, which comprises the following steps: forming N paths of coil output signals on the basis of M paths of radio frequency signals acquired by M coil units in the cylindrical surface coil, wherein N is an even integer more than one and less than or equal to M, the N paths of the coil output signals can be divided into N/2 pairs, and two paths of the coil output signals in each pair come from the coil units at symmetrical positions in the cylindrical surface coil respectively; and multiplying model values of the two paths of the coil output signals in each pair of the coil output signals to obtain N/2 products, summing the N/2 products, performing extraction of square root on the results of the summing, and generating cross sectional images according to the results of the extraction of square root. The invention also discloses a system for processing the radio frequency signal and the cylindrical surface coil. The signal intensity and the evenness of signal-noise ratio in an imaging region can be improved by applying the method, the system and the cylindrical surface coil.
Description
Technical field
The present invention relates to Magnetic resonance imaging (MRI, Magnetic Resonance Imaging) technology, particularly cylindrical surface coil, the frequency signal processing method that is used for cylindrical surface coil and system.
Background technology
The ultimate principle of MRI is: the hydrogen atom (can be other also, but hydrogen atom being the most frequently used) in the tissue can produce under the effect of fixed magnetic field and align; When adding a radio-frequency pulse, these hydrogen atoms will deflect under the effect of radio-frequency pulse; After radio-frequency pulse disappears, these hydrogen atoms all will return to original state; In the process of recovering, the radiofrequency signal that these hydrogen atoms produce is sampled, use the signal that collects to carry out image reconstruction then, just can obtain the image of tissue.Because the distribution of hydrogen atom in different tissues is different, therefore, can distinguish different tissues through resulting image.
Coil is the device that is used to gather said signal in the MRI equipment, and its ultimate principle is similar to a footpath receiving antenna.Coil can be divided into according to the relation with human body: body coil, surface coils etc.; Can be divided into according to shape: tubular coil, planar coil, helmet shape coil, fan-shaped coil etc.Knee coil is a kind of cylindrical surface coil, is example with the knee coil below, and the structure and the imaging characteristic thereof of existing cylindrical surface coil is described.
Fig. 1 shows the composition structural representation of existing knee coil.Referring to Fig. 1, wherein:
(a) part is tubular for the outward appearance of existing knee coil;
(b) part is the deployed configuration signal of existing knee endoprosthesis coil; According to deployed configuration signal, the composition unit of coil is a coil unit, among Fig. 1, is 6 to describe with the quantity of coil unit, shown in E1～E6 represent coil unit;
(c) part is 6 coil units when surrounding tubular, the position relation signal between each coil unit.
In the course of work of MRI equipment; Each coil unit all collects corresponding radiofrequency signal; The radiofrequency signal that is collected is a vector; These radiofrequency signals are sent out to the radiofrequency signal disposal system in the MRI equipment, and therefore, the signal that coil is sent to the radiofrequency signal disposal system is called coil output signal.The radiofrequency signal disposal system is used for coil output signal is carried out sending to image re-construction system to carry out image reconstruction after the radiofrequency signal processing, and Fig. 2 shows the structural representation of existing radiofrequency signal disposal system 200.Referring to Fig. 2, existing radiofrequency signal disposal system 200 comprises: N receiving cable 210 and a radiofrequency signal processing module 220.
Radiofrequency signal processing module 220 is used for that the coil output signal that receives is carried out radiofrequency signal and handles.In the prior art, said radiofrequency signal is handled and is exactly: to square summation of the mould value of each map output signal of receiving, and to obtain and extraction of square root.The result of said extraction of square root can be used for carrying out image reconstruction.With coil shown in Figure 1 is example, supposes that the quantity N of receiving cable equals the quantity M of coil neutralization coil unit, and then said radiofrequency signal is handled promptly: calculate square (S01
2+ S0
2+ ... + S06
2), wherein square representes extraction of square root, wherein S01, S02 ... S06 representes respectively from coil unit E1, E2 ... The radiofrequency signal of E6.
Image reconstruction will obtain three kinds of primary images: cross sectional image, sagittal view picture and coronal image, the image of other faces can be carried out certain conversion through said three kinds of primary images and obtained.
The signal intensity that coil unit collects in close in the surface coils is much larger than the signal intensity that collects at distant location.This just causes in the image that obtains according to said method; Zones of different (for example; The surf zone of cylindrical surface coil and central area) between the two difference of signal intensity and the signal to noise ratio (S/N ratio) that is directly proportional with signal intensity all bigger, that is: the uniformity coefficient of signal intensity and signal to noise ratio (S/N ratio) is poor in the imaging region.
Fig. 3 and Fig. 4 are the computer screen sectional drawing, show the cross sectional image of existing knee coil and the signal to noise ratio (S/N ratio) distribution schematic diagram of sagittal view picture respectively.Since the signal to noise ratio (S/N ratio) of coronal image distribute have with sagittal view as identical characteristic, therefore, the signal to noise ratio (S/N ratio) of not shown coronal image distributes in the present specification.Among Fig. 3 and Fig. 4, with isocontour embodied organization internal and tissue surface signal to noise ratio (S/N ratio), curve is intensive more, explains that difference is big more.Visible by Fig. 3 and Fig. 4; In the cross sectional image and sagittal view picture that the employing prior art obtains; The signal intensity of the signal intensity ratio organization internal of tissue surface is much bigger; Correspondingly, the signal to noise ratio (S/N ratio) of tissue surface is also big more a lot of than the signal to noise ratio (S/N ratio) of organization internal, that is: the uniformity coefficient of signal intensity in the imaging region and signal to noise ratio (S/N ratio) is all relatively poor.
Summary of the invention
In view of this; The invention discloses a kind of frequency signal processing method of cylindrical surface coil, a kind of radiofrequency signal disposal system and a kind of cylindrical surface coil that is used for cylindrical surface coil of being used for, to improve the uniformity coefficient of signal intensity in the cross sectional image imaging region and signal to noise ratio (S/N ratio).
For achieving the above object, technical scheme of the present invention specifically is achieved in that
A kind of frequency signal processing method that is used for cylindrical surface coil; Said cylindrical surface coil comprises M coil unit; M is the even number greater than 1; It is right that a said M coil unit is divided into M/2, and two coil units of every centering are arranged in the symmetric position in the said cylindrical surface coil, and this method comprises:
The M road radiofrequency signal that collects based on a said M coil unit; Form N map output signal; Wherein, N is greater than 1 and smaller or equal to the even number of M, and it is right that said N map output signal can be divided into N/2, and the two-way coil output signal of every centering is respectively from the coil unit that is arranged in said cylindrical surface coil symmetric position;
Mould value with two-way coil output signal in said every pair of coil output signal multiplies each other respectively, obtains N/2 product, said N/2 product is sued for peace, and the result of said summation is extracted square root, and the result of said extraction of square root is used to produce cross sectional image.
This method further comprises: with the mould value addition of said N map output signal, the result of said addition is used to produce sagittal view picture and/or coronal image.
When N equaled M, the step of said formation N map output signal comprised: the radiofrequency signal that each coil unit collects is exported signal as a map.
In one embodiment; As N during less than M; The step of said formation N map output signal comprises: all or part of coil unit in the said M coil unit is divided into N group, has at least two groups to comprise a coil unit, and have at least two groups to comprise the coil unit more than; It is right that a said N group can be divided into N/2, and two groups of coil units of every centering are arranged in the symmetric position of said cylindrical surface coil; For the group that includes only a coil unit, the radiofrequency signal that coil unit in this group collects is exported signal as a map; For the group that comprises more than a coil unit, the radiofrequency signal that all coils unit in this group is collected synthesizes map output signal.
In another embodiment; As N during less than M; The step of said formation N map output signal comprises: with the coil sections dividing elements in the said M coil unit is N group; Every group comprises a coil unit, and it is right that a said N group can be divided into N/2, and two groups of coil units of every centering are arranged in the symmetric position of said cylindrical surface coil; The radiofrequency signal that coil unit in every group is collected is as map output signal.
In another embodiment; As N during less than M; The step of said formation N map output signal comprises: all or part of coil unit in the said M coil unit is divided into N group; Every group comprises the coil unit more than, and a said N group can be divided into N/2 right, two groups of coil units of every centering are arranged in the symmetric position of said cylindrical surface coil; The radiofrequency signal that all coils unit in every group is collected synthesizes map output signal.
A kind of radiofrequency signal disposal system that is used for cylindrical surface coil; Said cylindrical surface coil comprises M coil unit; M is the even number greater than 1; It is right that a said M coil unit can be divided into M/2, and two coil units of every centering are arranged in the symmetric position of said cylindrical surface coil, and said radiofrequency signal disposal system comprises:
N receiving cable; Said N is greater than 1 and smaller or equal to the even number of M; Said radiofrequency signal disposal system receives the N map output signal from cylindrical surface coil through said N receiving cable; It is right that said N map output signal can be divided into N/2, and the two-way coil output signal of every centering is respectively from the coil unit that is arranged in said cylindrical surface coil symmetric position;
A multiplication unit is used for respectively the mould value of every pair of line output signal two-way coil output signal is multiplied each other, and obtains N/2 product;
One first adder unit is used for said N/2 product summation, the result who obtains suing for peace;
An extraction of square root unit is used for the result's extraction of square root to said summation, and the result of said extraction of square root is used to produce cross sectional image.
This radiofrequency signal disposal system may further include: one second adder unit, be used for mould value addition with said N map output signal, and the result of said addition is used to produce sagittal view picture and/or coronal image.
A kind of cylindrical surface coil comprises M coil unit, and M is the even number greater than 1, and it is right that a said M coil unit can be divided into M/2, and two coil units of every centering are arranged in the symmetric position of said cylindrical surface coil, and said cylindrical surface coil also comprises:
Memory module; The part or all of coil unit that is used for quantity N and a said M coil unit of storage coil output signal is divided into N the grouping when organizing and concerns; Wherein, N is greater than 1 and smaller or equal to the even number of M, it is right that a said N group can be divided into N/2, and two groups of coil units of every centering are arranged in the symmetric position of said cylindrical surface coil;
Signal forms module; Be used for according to said grouping relation; For the group that includes only a coil unit, the radiofrequency signal that this coil unit collects is exported signal as a map, and/or; For the group that comprises more than a coil unit, the radiofrequency signal that all coils unit in this group is collected synthesizes map output signal.
A said M coil unit constitutes a plurality of cartridges, and each cartridge comprises a plurality of coil units; Said a plurality of cartridge has the axis of coincidence, and adjacent successively on axis direction, and the adjacent cartridge half line coil unit that on the tangential of cross-sectional circumferential, staggers.
Visible by technique scheme; The present invention is in the process that the radiofrequency signal of cylindrical surface coil is handled; Mainly be used to mould long-pending sum on duty from the radiofrequency signal of symmetric position coil unit and replaced in the prior art quadratic sum from the radiofrequency signal of coil unit; Reduced effectively coil unit its nearby with the influence of the signal intensity difference that is collected at a distance; Thereby reduced in the cross sectional image imaging region difference of signal intensity and signal to noise ratio (S/N ratio) everywhere; Make that signal intensity and signal to noise ratio (S/N ratio) in the cross sectional image imaging region are more even with respect to prior art, thereby reached the purpose of improving interior signal intensity of imaging region and signal to noise ratio (S/N ratio) uniformity coefficient.In addition; The present invention is through the mould value addition with said N map output signal; Result according to addition produces sagittal view picture and/or coronal image; Reduced equally coil unit its nearby with the influence of the signal intensity difference that is collected at a distance, thereby improved signal intensity and signal to noise ratio (S/N ratio) uniformity coefficient in sagittal plane, the tubular cover imaging region.
Description of drawings
Describe exemplary embodiment of the present invention below with reference to accompanying drawings in detail, make clearer above-mentioned and other feature and advantage of the present invention of those of ordinary skill in the art, in the accompanying drawing:
Fig. 1 shows the composition structural representation of existing knee coil;
Fig. 2 shows the composition structural representation of existing radiofrequency signal disposal system;
Fig. 3 shows the computer screen sectional drawing of the signal to noise ratio (S/N ratio) distribution of the cross sectional image that has knee coil now, and wherein the unit of horizontal ordinate and ordinate is a millimeter;
Fig. 4 shows the computer screen sectional drawing of the signal to noise ratio (S/N ratio) distribution of the sagittal view picture that has knee coil now, and wherein the unit of horizontal ordinate and ordinate is a millimeter;
Fig. 5 is the schematic flow sheet of frequency signal processing method of the present invention;
Fig. 6 is the system architecture synoptic diagram of cylindrical surface coil of the present invention;
Fig. 7 illustrates the computer screen sectional drawing that the signal to noise ratio (S/N ratio) that adopts the knee cross sectional image that technical scheme of the present invention obtains distributes, and wherein the unit of horizontal ordinate and ordinate is millimeter;
Fig. 8 illustrates the computer screen sectional drawing that the signal to noise ratio (S/N ratio) that adopts the knee sagittal view picture that technical scheme of the present invention obtains distributes, and wherein the unit of horizontal ordinate and ordinate is millimeter;
Fig. 9 shows the composition structural representation of the present invention's one preferred cylindrical surface coil;
Figure 10 is the structural representation of a kind of radiofrequency signal disposal system in the embodiment of the invention.
Embodiment
For making the object of the invention, technical scheme and advantage clearer, below with reference to the accompanying drawing embodiment that develops simultaneously, the present invention is done further explain.
Main thought of the present invention is in the process that the radiofrequency signal of cylindrical surface coil is handled; Multiplex winding output signal through to cylindrical surface coil is handled accordingly; With reduced coil unit its nearby with the influence of the signal intensity difference that is collected at a distance, thereby reach the purpose of improving the uniformity coefficient of signal intensity and signal to noise ratio (S/N ratio) in the cross sectional image imaging region.
The cylindrical surface coil that the present invention was suitable for comprises M coil unit (M is the even number greater than 1); Each coil unit collects one tunnel radiofrequency signal; It is right that M in a cylindrical surface coil coil unit can be divided into M/2, and make two coil units in every pair of coil unit be arranged in the symmetric position in said cylindrical surface coil.That is to say that it is right the coil unit of the M in the cylindrical surface coil to be divided into M/2, and two coil units in every pair of coil unit are arranged in the symmetric position in the cylindrical surface coil.Situation when it should be noted that owing to deviation on the manufacturing process and use, this symmetry is not absolute, can allow certain deviation, exceeds not influence effect of the present invention.
Fig. 5 is the schematic flow sheet of frequency signal processing method of the present invention.Referring to Fig. 5, this method may further comprise the steps:
Step 501: the M road radiofrequency signal that collects based on the coil unit of M in the cylindrical surface coil; Form N map output signal (N is greater than 1 and smaller or equal to the even number of M); It is right to make that formed N map output signal can be divided into N/2, and the two-way coil of every centering output signal is respectively from the coil unit that is arranged in the cylindrical surface coil symmetric position.
In conjunction with knee coil shown in Figure 1; E1 and E4 are the coil units that is arranged in the cylindrical surface coil symmetric position described in the embodiment of the invention; Same, E2 and E5, E3 and E6 also are respectively the coil units that is arranged in the cylindrical surface coil symmetric position described in two pairs of embodiment of the invention.
Step 502: respectively formed N map output signal is transferred to the radiofrequency signal disposal system from cylindrical surface coil through N receiving cable, wherein, each receiving cable transmission of one line coil output signal.
Step 503: the radiofrequency signal disposal system receives the N map output signal that comes from cylindrical surface coil.
Step 504: at first, the mould value with the two-way coil output signal in the every pair of coil output signal in the step 501 multiplies each other respectively, obtains N/2 product.In other words, the two-way coil output signal that multiplies each other is respectively from the coil unit that is arranged in the cylindrical surface coil symmetric position.Then, to resulting N/2 product summation, and the result's extraction of square root to suing for peace.The result of extraction of square root can further send to image re-construction system, is used to produce cross sectional image.Wherein, produce in process and the prior art of cross sectional image according to square (S01 according to the result of extraction of square root
2+ S0
2+ ... + S06
2) produce the similar process of cross sectional image, that is, use the result of extraction of square root to carry out the subsequent treatment of image reconstruction, produce corresponding image.
In method shown in Figure 5, after step 503, can further include step 505: with the mould value addition of said N map output signal.The result of said addition can further send to the figure reconstructing system, is used to produce sagittal view picture and/or coronal image.Wherein, produce in process and the prior art of sagittal view picture and/or coronal image according to square (S01 according to the result of addition
2+ S02
2+ ... + S06
2) produce the similar process of sagittal view picture and/or coronal image, that is, use the result of addition to carry out the subsequent treatment of image reconstruction, produce corresponding image.In the radiofrequency signal processing procedure of the embodiment of the invention, do not limit the precedence of step 504 and step 505, be not limited to the precedence of rebuilding cross sectional image, sagittal view picture and coronal image in the successive image process of reconstruction yet.
Equal the situation of the quantity M of coil unit in the cylindrical surface coil for the quantity N of receiving cable in the radiofrequency signal disposal system; The M road radiofrequency signal that coil unit is gathered can be separately directly as the output of map output signal; Therefore; To this situation, the step 504 in the frequency signal processing method of the present invention is exactly: calculate square (S01*S04+S02*S05+S03*S06), the result of the square that is calculated (S01*S04+S02*S05+S03*S06) can further send to image re-construction system to be used to produce cross sectional image; Wherein, S01, S02 ... S06 representes respectively from coil unit E1, E2 ... The radiofrequency signal of E6.
Equal the situation of the quantity M of coil unit in the cylindrical surface coil for the quantity N of receiving cable in the radiofrequency signal disposal system; Step 505 in the embodiment of the invention frequency signal processing method is exactly: calculate abs (S01)+abs (S02)+abs (S03)+abs (S04)+abs (S05)+abs (S06); The result of abs (S01)+abs (S02)+abs (S03)+abs (S04)+abs (S05)+abs (S06) can further send to image re-construction system; Be used to produce sagittal view picture and/or coronal image; Wherein, S01, S02 ... S06 representes respectively from coil unit E1, E2 ... The radiofrequency signal of E6.
Here, square representes extraction of square root, and abs representes to take absolute value.
But; In practical application; The situation of the quantity N of receiving cable in the radiofrequency signal disposal system maybe be occurred, at this moment, N map output signal can be formed according to the M road radiofrequency signal that following mode is gathered based on coil unit less than the quantity M of coil unit in the cylindrical surface coil:
The 1st step: in advance whole M coil unit or wherein a part of coil unit are divided into N group, can comprise a coil unit in each group, also can comprise coil unit more than one.It all is to include only a coil unit that a kind of opposite extreme situations is every group.If the radiofrequency signal of certain coil unit collection can not used, division can not relate to this coil unit so.It is right that division makes that a resultant N group can be divided into N/2, and two groups of coil units of every centering are arranged in the symmetric position of cylindrical surface coil.
The 2nd step: in each group of dividing, the radiofrequency signal that collects according to coil unit in this group forms map output signal.For the group that includes only a coil unit, the radiofrequency signal that coil unit collects in directly will organizing is as map output signal.For the group that comprises more than a coil unit, the radiofrequency signal that all coils unit in this group is collected synthesizes map output signal.Because the symmetric relation when dividing, it is right that the N map that obtains at last output signal can be divided into N/2, and the two-way coil output signal of every centering is respectively from the coil unit that is arranged in the cylindrical surface coil symmetric position.
Below with the quantity of receiving cable be 4, the quantity of coil unit is that 6 (cylindrical surface coils as shown in Figure 1) are that example describes, that is: N=4, M=6.
In the 1st step, can whole 6 coil units be divided into 4 groups, the relation of grouping is: first group comprises E1 and E2, and second group comprises E3, and the 3rd group comprises E4 and E5, and the 4th group comprises E6.
In the 2nd step, in first group, the two-way radiofrequency signal that E1 and E2 are collected synthesizes a map and exports signal (being designated as S1); In second group, the radiofrequency signal that E3 collects is directly exported signal (being designated as S2) as a map; In the 3rd group, the two-way radiofrequency signal that E4 and E5 are collected synthesizes map output signal (being designated as S3); In the 4th group, the radiofrequency signal that E6 collects is directly exported signal (being designated as S4) as a map.Relation between each coil unit and the coil output signal can be expressed as:
E1+E2→S1
E3→S2
E4+E5→S3
E6→S4
Because F1 and E4 are that coil unit and the E2 and the E5 that are arranged in the cylindrical surface coil symmetric position are the coil units that is arranged in the cylindrical surface coil symmetric position; Therefore, S1 and S3 can think from the coil unit that is arranged in the cylindrical surface coil symmetric position; Because E3 and E6 itself are exactly the coil unit that is arranged in the cylindrical surface coil symmetric position, so S2 and S4 also are from the coil unit that is arranged in the cylindrical surface coil symmetric position.Therefore; S1, S2, S3 and S4 meet the condition of " it is right that N map output signal can be divided into N/2; the two-way coil output signal of every centering is respectively from the coil unit that is arranged in the cylindrical surface coil symmetric position " in the embodiment of the invention, can use S1, S2, S3 and S4 to carry out step 502 and subsequent step thereof.
In addition, also have the simplest a kind of mode, the E1 that can directly select to lay respectively at symmetric position in the cylindrical surface coil and E3 and E4 and E6 be respectively as one group, totally four groups.Because E1 and E4 are arranged in the symmetric position of cylindrical surface coil; E3 and E6 also are arranged in the symmetric position of cylindrical surface coil; Therefore; To export signal as 4 maps of output from RF signal S 01, S02, S03 and the S04 of selected E1, E3, E4 and E6, meet the condition of said " it is right that N map output signal can be divided into N/2, and the two-way coil output signal of every centering is respectively from the coil unit that is arranged in the cylindrical surface coil symmetric position ".Certainly, in practical application, also exist multiple mode to form N map output signal, repeat no more at this.
Corresponding to above-mentioned coil unit is divided into groups, and form the method that a map is exported signal, the invention provides a kind of cylindrical surface coil as shown in Figure 6 600 to every group of coil unit.Referring to Fig. 6, this cylindrical surface coil 600 comprises M coil unit 610, comprises that also memory module 620 and signal form module 630.
Wherein, it is right that M coil unit can be divided into M/2, and make two coil units in every pair of coil unit be arranged in the symmetric position of cylindrical surface coil 600.
Fig. 7 illustrates the computer screen sectional drawing that the signal to noise ratio (S/N ratio) that adopts the knee cross sectional image that embodiment of the invention technical scheme obtains distributes; Fig. 8 illustrates the computer screen sectional drawing that the signal to noise ratio (S/N ratio) that adopts the knee sagittal view picture that embodiment of the invention technical scheme obtains distributes.By Fig. 7 in contrast to Fig. 3, Fig. 8 in contrast to Fig. 4, can see and adopt embodiment of the invention technical scheme under the prerequisite that keeps than high s/n ratio, to improve the uniformity coefficient of signal to noise ratio (S/N ratio) in the imaging region significantly.
In order to obtain to improve preferably the effect of signal to noise ratio (S/N ratio) uniformity coefficient in the imaging region; Can construct the cylindrical surface coil that comprises 2 or 2 above cartridges and carry out signals collecting, and the method for the application embodiment of the invention is handled the radiofrequency signal that collects.Preferably, said 2 or 2 above cartridges have the axis of coincidence, and these cartridges are adjacent successively on axis direction, and the adjacent cartridge half line coil unit that on the tangential of cross-sectional circumferential, staggers.
Fig. 9 shows the composition structural representation of the present invention's one preferred cylindrical surface coil.Referring to Fig. 9, wherein:
(a) part is the outward appearance of this cylindrical surface coil; This cylindrical surface coil is tubular; Comprise two cartridges that are designated as cartridge 901 and following cartridge 902 respectively; Wherein go up cartridge 901 and have the axis of coincidence, and go up cartridge 901 and following cartridge 902 is adjacent one another are with following cartridge 902;
(b) part is the deployed configuration signal of this cylindrical surface coil.Last cartridge 901 comprises 6 coil units respectively with following cartridge 902, and E1～E6 belongs to cartridge 901, and E7～E12 belongs to cartridge 902 down.In order to decouple better, last cartridge 901 and the following cartridge 902 half line coil unit that staggered is equivalent to so in (a) part institute diagrammatic sketch, last cartridge 901 and the following cartridge 902 half line coil unit that on the cross-sectional circumferential tangential, staggers.
When (c) part surrounds tubular for said 12 coil units, the position relation signal between each coil unit.
In cylindrical surface coil shown in Figure 9, the coil unit that is arranged in the cylindrical surface coil symmetric position is to comprising: E1 and E4, E2 and E5, E3 and E6, E7 and E10, E8 and E11, E9 and E12.If select at least two above-mentioned coil units right; A coil unit of selected each coil unit centering is formed first group of coil unit; Another coil unit of each coil unit centering is formed second group of coil unit, and first group of coil unit and second group of coil unit are considered to be arranged in the symmetric position of cylindrical surface coil so.For example, first group comprises E1 and E2, and second group comprises E4 and E5; Perhaps, first group comprises E3 and E9, and second group comprises E6 and E12.
The frequency signal processing method that is used for cylindrical surface coil corresponding to the embodiment of the invention; The present invention also provides a kind of radiofrequency signal disposal system that is used for cylindrical surface coil; The cylindrical surface coil that this radiofrequency signal disposal system was suitable for comprises M coil unit (M is the even number greater than 1); Each coil unit collects one tunnel radiofrequency signal; It is right that M in a cylindrical surface coil coil unit can be divided into M/2, and make two coil units in every pair of coil unit be arranged in the symmetric position of said cylindrical surface coil.
Shown in figure 10, this radiofrequency signal disposal system 1000 comprises: N receiving cable 1010, multiplication unit 1020, one first adder unit 1030, an extraction of square root unit 1040, wherein N is greater than 1 and smaller or equal to the even number of M.
Shown in figure 10; Receive N map output signal through N receiving cable 1010 from cylindrical surface coil; It is right that N map output signal can be divided into N/2, and the two-way coil output signal of every centering is respectively from the coil unit that is arranged in the cylindrical surface coil symmetric position.
Extraction of square root unit 1040 is used for the result's extraction of square root from the summation of first adder unit 1030, and the result of extraction of square root can further send to follow-up image re-construction system (not shown), is used to produce cross sectional image.
In addition; Can further include one second adder unit 1050 in the radiofrequency signal disposal system 1000 of the present invention; Second adder unit 1050 is used for the mould value addition with the N map output signal that obtains from N receiving cable; The result of addition can further send to follow-up image re-construction system (not shown), is used to produce sagittal view picture and/or coronal image.
The above is merely the preferred embodiments of the present invention, is not to be used to limit protection scope of the present invention.All any modifications of within spirit of the present invention and principle, being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. frequency signal processing method that is used for cylindrical surface coil; Said cylindrical surface coil comprises M coil unit; M is the even number greater than 1; It is right that a said M coil unit is divided into M/2, and two coil units of every centering are arranged in the symmetric position in the said cylindrical surface coil, and this method comprises:
The M road radiofrequency signal that collects based on a said M coil unit; Form N map output signal; Wherein, N is greater than 1 and smaller or equal to the even number of M, and it is right that said N map output signal can be divided into N/2, and the two-way coil output signal of every centering is respectively from the coil unit that is arranged in said cylindrical surface coil symmetric position;
Mould value with two-way coil output signal in said every pair of coil output signal multiplies each other respectively, obtains N/2 product, said N/2 product is sued for peace, and the result of said summation is extracted square root, and the result of said extraction of square root can be used in the generation cross sectional image.
2. method according to claim 1 is characterized in that, this method further comprises:
With the mould value addition of said N map output signal, the result of said addition can be used in and produces sagittal view picture and/or coronal image.
3. method according to claim 1 and 2 is characterized in that, when N equaled M, the step of said formation N map output signal comprised:
The radiofrequency signal that each coil unit collects is exported signal as a map.
4. method according to claim 1 and 2 is characterized in that, as N during less than M, the step of said formation N map output signal comprises:
With the coil sections dividing elements in the said M coil unit is N group, and every group comprises a coil unit, and a said N group can be divided into N/2 right, two groups of coil units of every centering are arranged in the symmetric position of said cylindrical surface coil;
The radiofrequency signal that coil unit in every group is collected is as map output signal.
5. method according to claim 1 and 2 is characterized in that, as N during less than M, the step of said formation N map output signal comprises:
All or part of coil unit in the said M coil unit is divided into N group, and every group comprises the coil unit more than, and a said N group can be divided into N/2 right, two groups of coil units of every centering are arranged in the symmetric position of said cylindrical surface coil;
The radiofrequency signal that all coils unit in every group is collected synthesizes map output signal.
6. method according to claim 1 and 2 is characterized in that, as N during less than M, the step of said formation N map output signal comprises:
All or part of coil unit in the said M coil unit is divided into N group; Have at least two groups to comprise a coil unit; And have at least two groups to comprise coil unit more than one; It is right that a said N group can be divided into N/2, and two groups of coil units of every centering are arranged in the symmetric position of said cylindrical surface coil;
For the group that includes only a coil unit, the radiofrequency signal that coil unit in this group collects is exported signal as a map;
For the group that comprises more than a coil unit, the radiofrequency signal that all coils unit in this group is collected synthesizes map output signal.
7. radiofrequency signal disposal system that is used for cylindrical surface coil; Said cylindrical surface coil comprises M coil unit; M is the even number greater than 1; It is right that a said M coil unit can be divided into M/2, and two coil units of every centering are arranged in the symmetric position of said cylindrical surface coil, and said radiofrequency signal disposal system comprises:
N receiving cable (1010); Said N is greater than 1 and smaller or equal to the even number of M; Said radiofrequency signal disposal system receives the N map output signal from cylindrical surface coil through a said N receiving cable (1010); It is right that said N map output signal can be divided into N/2, and the two-way coil output signal of every centering is respectively from the coil unit that is arranged in said cylindrical surface coil symmetric position;
A multiplication unit (1020) is used for respectively the mould value of every pair of line output signal two-way coil output signal is multiplied each other, and obtains N/2 product;
One first adder unit (1030) is used for said N/2 product summation, the result who obtains suing for peace;
An extraction of square root unit (1040) is used for the result's extraction of square root to said summation, and the result of said extraction of square root can be used in the generation cross sectional image.
8. radiofrequency signal disposal system according to claim 7 is characterized in that, further comprises:
One second adder unit (1050) is used for the mould value addition with said N map output signal, and the result of said addition can be used in and produces sagittal view picture and/or coronal image.
9. a cylindrical surface coil comprises M coil unit (610), and M is the even number greater than 1; It is right that a said M coil unit can be divided into M/2; Two coil units of every centering are arranged in the symmetric position of said cylindrical surface coil, it is characterized in that, said cylindrical surface coil also comprises:
Memory module (620); The part or all of coil unit that is used for quantity N and a said M coil unit of storage coil output signal is divided into N the grouping when organizing and concerns; Wherein, N is greater than 1 and smaller or equal to the even number of M, it is right that a said N group can be divided into N/2, and two groups of coil units of every centering are arranged in the symmetric position of said cylindrical surface coil;
Signal forms module (630); Be used for according to said grouping relation; For the group that includes only a coil unit; The radiofrequency signal that this coil unit collects is exported signal as a map, and/or for the group that comprises more than a coil unit, the radiofrequency signal that all coils unit in this group is collected synthesizes map output signal.
10. cylindrical surface coil according to claim 9 is characterized in that, a said M coil unit (610) constitutes a plurality of cartridges (901,902), and each cartridge (901,902) comprises a plurality of coil units;
Said a plurality of cartridge (901,902) has the axis of coincidence, and adjacent successively on axis direction, and adjacent cartridge (901,902) the half line coil unit that on the tangential of cross-sectional circumferential, staggers.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4982162A (en) * | 1989-07-14 | 1991-01-01 | Advanced Nmr Systems, Inc. | Method for reconstructing MRI signals resulting from time-varying gradients |
| CN1468583A (en) * | 2002-06-07 | 2004-01-21 | Ge医疗系统环球技术有限公司 | Coil sensitive graph generating method and parallel imaging method and magnetic resonance imaging apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4982162A (en) * | 1989-07-14 | 1991-01-01 | Advanced Nmr Systems, Inc. | Method for reconstructing MRI signals resulting from time-varying gradients |
| CN1468583A (en) * | 2002-06-07 | 2004-01-21 | Ge医疗系统环球技术有限公司 | Coil sensitive graph generating method and parallel imaging method and magnetic resonance imaging apparatus |
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