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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 PDF

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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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coil
cylindrical surface
unit
units
radio frequency
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CN101545960A (en
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王海宁
汪坚敏
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Siemens Healthcare Ltd
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Siemens Ltd China
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Abstract

本发明提供了一种用于筒状表面线圈的射频信号处理方法,该方法包括:基于所述筒状表面线圈中的M个线圈单元采集得到的M路射频信号,形成N路线圈输出信号,其中,N为大于1且小于等于M的偶数,所述N路线圈输出信号可分为N/2对,每对中的两路线圈输出信号分别来自位于所述筒状表面线圈中对称位置的线圈单元;分别将所述每对线圈输出信号中两路线圈输出信号的模值相乘,得到N/2个乘积,对所述N/2个乘积求和,并对所述求和的结果开平方,根据所述开平方的结果产生横截面图像。本发明还公开了一种射频信号处理系统以及一种筒状表面线圈。应用本发明能够改善成像区域内信号强度及信噪比的均匀度。

Figure 200810084139

The present invention provides a radio frequency signal processing method for a tubular surface coil, the method comprising: forming N coil output signals based on M radio frequency signals collected by M coil units in the tubular surface coil, Wherein, N is an even number greater than 1 and less than or equal to M, and the N-way coil output signals can be divided into N/2 pairs, and the two-way coil output signals in each pair come from the symmetrical positions of the cylindrical surface coils respectively. Coil unit; respectively multiply the modulus values of the two coil output signals in each pair of coil output signals to obtain N/2 products, sum the N/2 products, and calculate the result of the summation square root, and generate a cross-sectional image according to the result of the square root. The invention also discloses a radio frequency signal processing system and a cylindrical surface coil. The application of the invention can improve the uniformity of signal intensity and signal-to-noise ratio in the imaging area.

Figure 200810084139

Description

Cylindrical surface coil and be used for its frequency signal processing method and system
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.
N receiving cable 210 is used to receive the N map output signal that comes from coil, and said N map output signal is sent to radiofrequency signal processing module 220; Said N is for greater than 1 and smaller or equal to the integer (following quantity with the coil neutralization coil unit is designated as M, and M is the integer greater than 1) of coil neutralization coil unit quantity.If the quantity N of receiving cable equals the quantity M of coil neutralization coil unit; Then M road radiofrequency signal can be directly as coil output signal; Send to N corresponding receiving cable; If the quantity N of receiving cable is less than the quantity M of coil neutralization coil unit, then M road radiofrequency signal can be passed through the synthetic N map output signal that forms afterwards of certain signal, sends to N corresponding receiving cable.
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.
Memory module 620 be used for the quantity N of storage coil output signal and all the coil sections unit in M coil unit or M the coil unit be divided into N the grouping when organizing and concern; 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 make two groups of coil units of every centering be arranged in the symmetric position of cylindrical surface coil 600.
Signal forms module 630 and is used for the grouping relation according to memory module 620; The radiofrequency signal that coil unit in the group that includes only a coil unit collects is exported signal as a map; And/or, will comprise that the radiofrequency signal that collects more than all coils unit in the group of a coil unit synthesizes map output signal.
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.
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, and this N/2 product is offered first adder unit 1030.
First adder unit 1030 is used for N/2 the product that receives from multiplication unit 1020 sued for peace, the result who obtains suing for peace, and the result that will sue for peace offers extraction of square root unit 1040.
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)

1.一种用于筒状表面线圈的射频信号处理方法,所述筒状表面线圈包括M个线圈单元,M为大于1的偶数,将所述M个线圈单元分为M/2对,并将每对中的两个线圈单元布置在所述筒状表面线圈中的对称位置,该方法包括:1. A radio frequency signal processing method for a cylindrical surface coil, the cylindrical surface coil comprises M coil units, M is an even number greater than 1, the M coil units are divided into M/2 pairs, and Arranging the two coil units of each pair at symmetrical positions in the cylindrical surface coil, the method comprising: 基于所述M个线圈单元采集得到的M路射频信号,形成N路线圈输出信号,其中,N为大于1且小于等于M的偶数,所述N路线圈输出信号可分为N/2对,每对中的两路线圈输出信号分别来自位于所述筒状表面线圈中对称位置的线圈单元;Based on the M radio frequency signals collected by the M coil units, N coil output signals are formed, where N is an even number greater than 1 and less than or equal to M, and the N coil output signals can be divided into N/2 pairs, The output signals of the two coils in each pair are respectively from coil units located at symmetrical positions in the cylindrical surface coil; 分别将所述每对线圈输出信号中两路线圈输出信号的模值相乘,得到N/2个乘积,对所述N/2个乘积求和,并对所述求和的结果开平方,所述开平方的结果能够用于产生横截面图像。Respectively multiply the modulus values of the two coil output signals in each pair of coil output signals to obtain N/2 products, sum the N/2 products, and take the square root of the summed results, The result of the square root can be used to generate a cross-sectional image. 2.根据权利要求1所述的方法,其特征在于,该方法进一步包括:2. The method according to claim 1, characterized in that the method further comprises: 将所述N路线圈输出信号的模值相加,所述相加的结果能够用于产生矢状面图像和/或冠状面图像。The modulus values of the output signals of the N circuits of coils are added, and the result of the addition can be used to generate a sagittal plane image and/or a coronal plane image. 3.根据权利要求1或2所述的方法,其特征在于,当N等于M时,所述形成N路线圈输出信号的步骤包括:3. The method according to claim 1 or 2, wherein when N is equal to M, the step of forming an N-way coil output signal comprises: 将每个线圈单元采集得到的射频信号作为一路线圈输出信号。The radio frequency signal collected by each coil unit is used as a coil output signal. 4.根据权利要求1或2所述的方法,其特征在于,当N小于M时,所述形成N路线圈输出信号的步骤包括:4. The method according to claim 1 or 2, wherein when N is less than M, the step of forming the output signal of N coils comprises: 将所述M个线圈单元中的部分线圈单元划分为N个组,每组包括一个线圈单元,并且所述N个组可分为N/2对,每对中的两组线圈单元位于所述筒状表面线圈中的对称位置;Part of the coil units in the M coil units are divided into N groups, each group includes a coil unit, and the N groups can be divided into N/2 pairs, and the two groups of coil units in each pair are located in the Symmetrical positions in cylindrical surface coils; 将每组中线圈单元采集得到的射频信号作为一路线圈输出信号。The radio frequency signal collected by the coil unit in each group is used as a coil output signal. 5.根据权利要求1或2所述的方法,其特征在于,当N小于M时,所述形成N路线圈输出信号的步骤包括:5. The method according to claim 1 or 2, wherein when N is less than M, the step of forming an N-way coil output signal comprises: 将所述M个线圈单元中的全部或者部分线圈单元划分为N个组,每组包括多于一个的线圈单元,并且所述N个组可分为N/2对,每对中的两组线圈单元位于所述筒状表面线圈中的对称位置;All or part of the coil units in the M coil units are divided into N groups, each group includes more than one coil unit, and the N groups can be divided into N/2 pairs, and two groups in each pair The coil unit is located at a symmetrical position in the cylindrical surface coil; 将每组中所有线圈单元采集得到的射频信号合成为一路线圈输出信号。The radio frequency signals collected by all the coil units in each group are synthesized into one coil output signal. 6.根据权利要求1或2所述的方法,其特征在于,当N小于M时,所述形成N路线圈输出信号的步骤包括:6. The method according to claim 1 or 2, wherein when N is less than M, the step of forming an N-way coil output signal comprises: 将所述M个线圈单元中的全部或者部分线圈单元划分为N个组,至少有两个组包括一个线圈单元,并且至少有两个组包括多于一个的线圈单元,所述N个组可分为N/2对,每对中的两组线圈单元位于所述筒状表面线圈中的对称位置;All or part of the coil units in the M coil units are divided into N groups, at least two groups include one coil unit, and at least two groups include more than one coil unit, and the N groups can be Divided into N/2 pairs, the two groups of coil units in each pair are located at symmetrical positions in the cylindrical surface coil; 对于只包括一个线圈单元的组,将该组中线圈单元采集得到的射频信号作为一路线圈输出信号;For a group including only one coil unit, the radio frequency signal collected by the coil unit in the group is used as a coil output signal; 对于包括多于一个线圈单元的组,将该组中所有线圈单元采集得到的射频信号合成为一路线圈输出信号。For a group including more than one coil unit, the radio frequency signals collected by all the coil units in the group are synthesized into one coil output signal. 7.一种用于筒状表面线圈的射频信号处理系统,所述筒状表面线圈包括M个线圈单元,M为大于1的偶数,所述M个线圈单元可分为M/2对,每对中的两个线圈单元位于所述筒状表面线圈中的对称位置,所述射频信号处理系统包括:7. A radio frequency signal processing system for a cylindrical surface coil, the cylindrical surface coil includes M coil units, M is an even number greater than 1, and the M coil units can be divided into M/2 pairs, each The two coil units in the center are located at symmetrical positions in the cylindrical surface coil, and the radio frequency signal processing system includes: N个接收通道(1010),所述N为大于1且小于等于M的偶数,所述射频信号处理系统通过所述N个接收通道(1010)接收来自筒状表面线圈的N路线圈输出信号,所述N路线圈输出信号可分为N/2对,每对中的两路线圈输出信号分别来自位于所述筒状表面线圈中对称位置的线圈单元;N receiving channels (1010), wherein N is an even number greater than 1 and less than or equal to M, and the radio frequency signal processing system receives N coil output signals from the cylindrical surface coil through the N receiving channels (1010), The N-way coil output signals can be divided into N/2 pairs, and the two-way coil output signals in each pair are respectively from coil units located at symmetrical positions in the cylindrical surface coil; 一个乘法单元(1020),用于分别将每对线路输出信号中两路线圈输出信号的模值相乘,得到N/2个乘积;A multiplication unit (1020), which is used to multiply the modulus values of the two coil output signals in each pair of line output signals to obtain N/2 products; 一个第一加法单元(1030),用于对所述N/2个乘积求和,得到求和的结果;A first addition unit (1030), used for summing the N/2 products to obtain a summed result; 一个开平方单元(1040),用于对所述求和的结果开平方,所述开平方的结果能够用于产生横截面图像。A square root unit (1040) for taking the square root of the result of the summation, and the square root result can be used to generate a cross-sectional image. 8.根据权利要求7所述的射频信号处理系统,其特征在于,进一步包括:8. The radio frequency signal processing system according to claim 7, further comprising: 一个第二加法单元(1050),用于将所述N路线圈输出信号的模值相加,所述相加的结果能够用于产生矢状面图像和/或冠状面图像。A second adding unit (1050), configured to add the modulus values of the output signals of the N coils, and the result of the addition can be used to generate a sagittal plane image and/or a coronal plane image. 9.一种筒状表面线圈,包括M个线圈单元(610),M为大于1的偶数,所述M个线圈单元可分为M/2对,每对中的两个线圈单元位于所述筒状表面线圈中的对称位置,其特征在于,所述筒状表面线圈还包括:9. A cylindrical surface coil, comprising M coil units (610), M being an even number greater than 1, the M coil units can be divided into M/2 pairs, and two coil units in each pair are positioned at the The symmetrical position in the cylindrical surface coil is characterized in that the cylindrical surface coil also includes: 存储模块(620),用于存储线圈输出信号的数量N、以及所述M个线圈单元中的部分或全部线圈单元被分为N个组时的分组关系,其中,N为大于1且小于等于M的偶数,所述N个组可分为N/2对,每对中的两组线圈单元位于所述筒状表面线圈中的对称位置;A storage module (620), configured to store the number N of coil output signals and the grouping relationship when some or all of the coil units in the M coil units are divided into N groups, wherein N is greater than 1 and less than or equal to M is an even number, the N groups can be divided into N/2 pairs, and the two groups of coil units in each pair are located at symmetrical positions in the cylindrical surface coil; 信号形成模块(630),用于根据所述分组关系,对于只包括一个线圈单元的组,将该线圈单元采集得到的射频信号作为一路线圈输出信号,和/或对于包括多于一个线圈单元的组,将该组中所有线圈单元采集得到的射频信号合成为一路线圈输出信号。A signal forming module (630), configured to, according to the grouping relationship, for a group that includes only one coil unit, use the radio frequency signal collected by the coil unit as a coil output signal, and/or for a group that includes more than one coil unit group, and synthesize the radio frequency signals collected by all the coil units in the group into one coil output signal. 10.根据权利要求9所述的筒状表面线圈,其特征在于,所述M个线圈单元(610)构成复数个筒状部件(901,902),每个筒状部件(901,902)包括复数个线圈单元;10. The cylindrical surface coil according to claim 9, characterized in that, the M coil units (610) form a plurality of cylindrical parts (901, 902), and each cylindrical part (901, 902) includes A plurality of coil units; 所述复数个筒状部件(901,902)具有重合的轴线,且在轴线方向上依次相邻,并且相邻的筒状部件(901,902)在横截面圆周的切向上错开半个线圈单元。The plurality of cylindrical components (901, 902) have coincident axes and are adjacent to each other in the axial direction, and the adjacent cylindrical components (901, 902) are staggered by half a coil unit in the tangential direction of the cross-sectional circumference .
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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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