U.S. patent application number 11/554951 was filed with the patent office on 2008-05-01 for flexible rf coil assembly and method of making same.
Invention is credited to Christopher J. Hardy, Kenneth W. Rohling.
Application Number | 20080100294 11/554951 |
Document ID | / |
Family ID | 39321658 |
Filed Date | 2008-05-01 |
United States Patent
Application |
20080100294 |
Kind Code |
A1 |
Rohling; Kenneth W. ; et
al. |
May 1, 2008 |
FLEXIBLE RF COIL ASSEMBLY AND METHOD OF MAKING SAME
Abstract
An RF coil assembly includes a plurality of coil supports
rotatably interconnected to each other. Each coil support is
configured to rotate with respect to at least one adjoining coil
support. A plurality of RF coils is connected to each coil
support.
Inventors: |
Rohling; Kenneth W.;
(Niskayuna, NY) ; Hardy; Christopher J.;
(Niskayuna, NY) |
Correspondence
Address: |
GENERAL ELECTRIC COMPANY;GLOBAL RESEARCH
PATENT DOCKET RM. BLDG. K1-4A59
NISKAYUNA
NY
12309
US
|
Family ID: |
39321658 |
Appl. No.: |
11/554951 |
Filed: |
October 31, 2006 |
Current U.S.
Class: |
324/318 |
Current CPC
Class: |
G01R 33/34007 20130101;
G01R 33/34084 20130101; G01R 33/3415 20130101 |
Class at
Publication: |
324/318 |
International
Class: |
G01V 3/00 20060101
G01V003/00 |
Claims
1. An MRI apparatus comprising: a magnetic resonance imaging (MRI)
system having a plurality of gradient coils positioned about a bore
of a magnet to Impress spatially dependent changes to a polarizing
magnetic field and an RF transceiver system and an RF switch
controlled by a pulse module to transmit RF magnetic fields from an
RF transmit coil to excite MR signals and to acquire MR signals
using an RF receiver coil assembly to create MR images, the RF coil
assembly comprising: a pair of RF coil modules, each RF coil module
comprising: a set of overlapping RF coils; and a housing rigidly
supporting the set of overlapping RF coils; and at least one hinge
connected to each of the pair of RF coil modules and configured to
permit the pair of RF coil modules to rotate between an unflexed
position and a flexed position; wherein each of the Pair of RF coil
modules further comprises: a rib attached thereto; and a plurality
of electrical components for each RF coil in the set of overlapping
RF coils; and, wherein the rib comprises a printed circuit board of
at least one side, having an electrical circuit for each RF coil in
the set of overlapping RF coils, and wherein the oluralitv of
electrical components for each RF coil is electrically connected to
a corresponding electrical circuit.
2-3. (canceled)
4. The MRI apparatus of claim 1 further comprising a rigid housing
configured to enclose the rib and the plurality of electrical
components connected thereto.
5. The MRI apparatus of claim 1 wherein the RF coil assembly
further comprises an end connector attached to each rigid housing
enclosing a rib, the end connector having a passage therethrough
configured to guide a plurality of wires onto a corresponding rib,
each wire electrically connected to a corresponding electrical
circuit.
6. (canceled)
7. The MRI apparatus of claim 1 wherein the plurality of electrical
components comprises a preamplifier, a balun, at least one
capacitor, and at least one diode.
8. The MRI apparatus of claim 1 wherein each of the pair of RF coil
modules further comprises: a first link connected to a first end of
the rib; a second link connected to a second end of the rib; and
wherein the at least one hinge comprises: a first hinge connected
to the first link of one of the pair of RF coil modules and
connected to the first link of the other of the pair of RF coil
modules; and a second hinge connected to the second link of one of
the pair of RF coil modules and connected to the second link of the
other of the pair of RF coil modules.
9. The MRI apparatus of claim 1 wherein the housing comprises a
printed circuit board having at least one side, and wherein the set
of overlapping RF coils is etched on the printed circuit board.
10. The MRI apparatus of claim 1 wherein the at least one hinge is
one of a piano hinge and a butt hinge.
11. The MRI apparatus of claim 1 wherein the at least one hinge is
a cam hinge system comprising: a cam; and a cam follower configured
to mate with the cam wherein the cam has a groove formed therein
and wherein the cam follower comprises at least one projection
configured to engage the groove the cam further comprises a knob
extending from a surface thereof and configured to engage a first
portion of an elastic member, and wherein the cam follower further
comprises a knob extending from a surface thereof and configured to
engage a second portion of the elastic member.
12-13. (canceled)
14. The MRI apparatus of claim 1 wherein at least one hinge is
connected to each housing of the pair of RF coil modules.
15. An RF coil assembly comprising: a plurality of RF coil sets; a
plurality of RF coil modules rotatably interconnected to each
other, each RF coil module rigidly connected to one of the
plurality of RF coil sets and configured to rotate with respect to
at least one adjoining RF coil module; and, a hinge system
connected to adjoining RF coil modules and configured to allow the
adjoining RF coil modules to rotate with respect to each other,
wherein the hinge system is a cam hinge system comprising: a cam
attached to one of the adjoining RF coil modules; and a cam
follower configured to mate with the cam and attached to the other
of the adjoining RF coil modules.
16-17. (canceled)
18. The RF coil assembly of claim 15 wherein the cam hinge system
is configured to vary an overlap of adjacent edges of the adjoining
RF coil modules as the adjoining RF coil modules rotate with
respect to each other.
19. The RF coil assembly of claim 15 wherein each RF coil module is
further configured to maintain the RF coil set connected thereto in
an unflexed state during rotation thereof with respect to the at
least one adjoining RF coil module.
20. A method of making an RF coil array comprising the steps of:
connecting a first plurality of RF coils to a first rigid support;
connecting a second plurality of RF coils to a second rigid
support; and attaching at least one hinge between the first and
second rigid supports; wherein the step of attaching further
comprises: attaching a cam interface to the first rigid support;
attaching a cam follower interface to the second rigid support; and
interconnecting the cam interface to the cam follower
interface,
21. (canceled)
22. The method of claim 20 wherein the step of attaching further
comprises attaching one of a piano hinge and a butt hinge between
the first and second rigid supports.
23. The method of claim 20 further comprising the steps of: forming
a portion of each of the first and second rigid supports from a
printed circuit board of at least one side; electrically connecting
a respective RF coil to an electrical circuit on the printed
circuit board; and electrically connecting a plurality of
electrical components to each respective RF coil.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to MR imaging and,
more particularly, to a flexible RF coil assembly capable of
conforming to a patient's shape.
[0002] When a substance such as human tissue is subjected to a
uniform magnetic field (polarizing field B.sub.0), the individual
magnetic moments of the spins in the tissue attempt to align with
this polarizing field, but precess about it in random order at
their characteristic Larmor frequency. If the substance, or tissue,
is subjected to a magnetic field (excitation field B.sub.1) which
is in the x-y plane and which is near the Larmor frequency, the net
aligned moment, or "longitudinal magnetization", M.sub.Z, may be
rotated, or "tipped", into the x-y plane to produce a net
transverse magnetic moment M.sub.t. A signal is emitted by the
excited spins after the excitation signal B.sub.1 is terminated and
this signal may be received and processed to form an image.
[0003] When utilizing these signals to produce images, magnetic
field gradients (G.sub.x, G.sub.y, and G.sub.z) are employed.
Typically, the region to be imaged is scanned by a sequence of
measurement cycles in which these gradients vary according to the
particular localization method being used. The resulting set of
received NMR signals are digitized and processed to reconstruct the
image using one of many well known reconstruction techniques.
[0004] It is desired that RF receiver-coil arrays be made light and
flexible so that all of the coils can be positioned close to a
patient and that patient comfort may be maintained while fitting an
RF receiver-coil array to a variety of patient sizes and shapes.
However, repeated flexing of RF receiver coils and their
corresponding circuitry may alter the performance and shorten the
working life of the RF receiver coils.
[0005] It would therefore be desirable to have an RF coil apparatus
capable of conforming to a patient's shape while protecting the RF
receiver coils and corresponding circuitry from repeated
flexing.
BRIEF DESCRIPTION OF THE INVENTION
[0006] The present invention provides an RF coil apparatus that
overcomes the aforementioned drawbacks. An RF coil assembly
includes a plurality of coil supports rotatably interconnected to
each other. Each coil support is configured to rotate with respect
to at least one adjoining coil support. A plurality of RF coils is
connected to each coil support.
[0007] Therefore, according to an aspect of the present invention,
an MRI apparatus includes a magnetic resonance imaging (MRI) system
having a plurality of gradient coils positioned about a bore of a
magnet to impress spatially dependent changes to a polarizing
magnetic field and an RF transceiver system and an RF switch
controlled by a pulse module to transmit RF magnetic fields from an
RF transmit coil to excite MR signals and to acquire MR signals
using an RF receiver coil assembly to create MR images. The RF coil
assembly includes a pair of RF coil modules. Each RF coil module
includes a set of overlapping RF coils and a housing rigidly
supporting the set of overlapping RF coils. The RF coil assembly
includes at least one hinge connected to each of the pair of RF
coil modules and configured to permit the pair of RF coil modules
to rotate between an unflexed position and a flexed position.
[0008] According to another aspect of the present invention, an RF
coil assembly includes a plurality of RF coil sets. The assembly
also includes a plurality of RF coil modules rotatably
interconnected to each other, each RF coil module rigidly connected
to one of the plurality of RF coil sets and configured to rotate
with respect to at least one adjoining RF coil module.
[0009] According to a further aspect of the present invention, a
method of making an RF coil array includes connecting a first
plurality of RF coils to a first rigid support and connecting a
second plurality of RF coils to a second rigid support. The method
also includes attaching at least one hinge between the first and
second rigid supports.
[0010] Various other features and advantages of the present
invention will be made apparent from the following detailed
description and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The drawings illustrate one preferred embodiment presently
contemplated for carrying out the invention.
[0012] In the drawings:
[0013] FIG. 1 is a schematic block diagram of an MR imaging system
for use with the present invention.
[0014] FIG. 2 is a schematic diagram of an RF coil array according
to one embodiment of the present invention.
[0015] FIG. 3 is a perspective view of a portion of a rib of the RF
coil array of FIG. 2 in accordance with an embodiment of the
present invention.
[0016] FIG. 4 is a perspective view of the RF coil array 70 of FIG.
2 having the modules 74-86 protectively covered.
[0017] FIG. 5 is a side plan view of the RF coil array of FIG. 2 in
an unflexed position according to an embodiment of the present
invention.
[0018] FIG. 6 is a side plan view of RF coil array of FIG. 2 in a
flexed position according to an embodiment of the present
invention.
[0019] FIG. 7 is an exemplary RF coil displacement plot
illustrating a displacement of the RF coils during rotation.
[0020] FIG. 8 is a schematic diagram showing rotation and
translation of a pair of RF coils with respect to each other coil
according to an embodiment of the present invention.
[0021] FIG. 9 is a perspective view of a cam system usable with the
RF coil array of FIG. 2 in accordance with one embodiment of the
present invention.
[0022] FIG. 10 is a schematic diagram of an RF coil array according
to another embodiment of the present invention.
[0023] FIG. 11 is a side plan view of the RF coil array of FIG. 10
in an unflexed position according to an embodiment of the present
invention.
[0024] FIG. 12 is a side plan view of the RF coil array of FIG. 10
in a flexed position according to an embodiment of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0025] Referring to FIG. 1, the major components of a preferred
magnetic resonance imaging (MRI) system 10 incorporating the
present invention are shown. The operation of the system is
controlled from an operator console 12 which includes a keyboard or
other input device 13, a control panel 14, and a display screen 16.
The console 12 communicates through a link 18 with a separate
computer system 20 that enables an operator to control the
production and display of images on the display screen 16. The
computer system 20 includes a number of modules which communicate
with each other through a backplane 20a. These include an image
processor module 22, a CPU module 24 and a memory module 26, known
in the art as a frame buffer for storing image data arrays. The
computer system 20 is linked to disk storage 28 and removable
storage 30 for storage of image data and programs, and communicates
with a separate system control 32 through a high speed serial link
34. The input device 13 can include a mouse, joystick, keyboard,
track ball, touch activated screen, light wand, voice control, or
any similar or equivalent input device, and may be used for
interactive geometry prescription.
[0026] The system control 32 includes a set of modules connected
together by a backplane 32a. These include a CPU module 36 and a
pulse generator module 38 which connects to the operator console 12
through a serial link 40. It is through link 40 that the system
control 32 receives commands from the operator to indicate the scan
sequence that is to be performed. The pulse generator module 38
operates the system components to carry out the desired scan
sequence and produces data which indicates the timing, strength and
shape of the RF pulses produced, and the timing and length of the
data acquisition window. The pulse generator module 38 connects to
a set of gradient amplifiers 42, to indicate the timing and shape
of the gradient pulses that are produced during the scan. The pulse
generator module 38 can also receive patient data from a
physiological acquisition controller 44 that receives signals from
a number of different sensors connected to the patient, such as ECG
signals from electrodes attached to the patient. And finally, the
pulse generator module 38 connects to a scan room interface circuit
46 which receives signals from various sensors associated with the
condition of the patient and the magnet system. It is also through
the scan room interface circuit 46 that a patient positioning
system 48 receives commands to move the patient to the desired
position for the scan.
[0027] The gradient waveforms produced by the pulse generator
module 38 are applied to the gradient amplifier system 42 having
Gx, Gy, and Gz amplifiers. Each gradient amplifier excites a
corresponding physical gradient coil in a gradient coil assembly
generally designated 50 to produce the magnetic field gradients
used for spatially encoding acquired signals. The gradient coil
assembly 50 forms part of a magnet assembly 52 which includes a
polarizing magnet 54 and a whole-body RF coil 56. A transceiver
module 58 in the system control 32 produces pulses which are
amplified by an RF amplifier 60 and coupled to the RF coil 56 by a
transmit/receive switch 62. The resulting signals emitted by the
excited nuclei in the patient may be sensed by the same RF coil 56
and coupled through the transmit/receive switch 62 to a
preamplifier 64. The amplified MR signals are demodulated,
filtered, and digitized in the receiver section of the transceiver
58. The transmit/receive switch 62 is controlled by a signal from
the pulse generator module 38 to electrically connect the RF
amplifier 60 to the coil 56 during the transmit mode and to connect
the preamplifier 64 to the coil 56 during the receive mode. The
transmit/receive switch 62 can also enable a separate RF coil (for
example, a surface coil) to be used in either the transmit or
receive mode.
[0028] The MR signals picked up by the RF coil 56 are digitized by
the transceiver module 58 and transferred to a memory module 66 in
the system control 32. A scan is complete when an array of raw
k-space data has been acquired in the memory module 66. This raw
k-space data is rearranged into separate k-space data arrays for
each image to be reconstructed, and each of these is input to an
array processor 68 which operates to Fourier transform the data
into an array of image data. This image data is conveyed through
the serial link 34 to the computer system 20 where it is stored in
memory, such as disk storage 28. In response to commands received
from the operator console 12, this image data may be archived in
long term storage, such as on the removable storage 30, or it may
be further processed by the image processor 22 and conveyed to the
operator console 12 and presented on the display 16.
[0029] FIG. 2 shows a schematic diagram of an RF coil array 70
according to one embodiment of the present invention. RF coil array
70 includes a plurality of RF coils 72 positioned relative to each
other such that a mutual inductance between each nearest-neighbor
coil 72 is minimized. Preferably, the mutual inductance between
coils 72 is zero. RF coil array 70 includes a plurality of modules
74-86 rotatably interconnected to each other. Each module 74-78,
82-86 has a column 88 of overlapping RF coils 72. Center module 80
has two columns 88 of overlapping RF coils 72 attached thereto.
Each column 88 of RF coils 72 is attached to a rib 90 having a
plurality of electrical components (shown in FIG. 3) for each RF
coil circuit in the column 88. An end connector 92 having a passage
94 therethrough is connected to each rib 90. Wires 96 are routed
through the passage 94 and connect each RF coil circuit to the MR
system 10 of FIG. 1.
[0030] FIG. 3 shows a perspective view of a portion of a module
74-86 of FIG. 2 in accordance with an embodiment of the present
invention. In a preferred embodiment, rib 90 is a printed circuit
board (PCB) 98 having a plurality of electrical circuits 100 on one
side 101. However, the plurality of electrical circuits 100 may
also be etched on two sides 101, 103 of PCB 98. Alternatively, it
is contemplated that rib 90 may constructed of a lightweight
material and that a separate PCB or equivalently etched substrate
may be attached thereto. The plurality of electrical circuits 100
include components 102 such as a balun 104, a variable capacitor
106, and a diode 108 electrically connected to each RF coil 72. One
skilled in the art will recognize that, while one variable
capacitor 106 and one diode 108 are shown in FIG. 3, more than one
variable capacitor 106 and more than one diode 108 may be connected
to each RF coil 72. Wires 96 further connect each electrical
circuit 100 to a preamplifier 64 (FIG. 1) and relay signals
received by the RF coils 72 through the plurality of end connectors
92 (FIG. 2) to the system control 32 (FIG. 1). The ribs 90 provide
structural support for the electrical circuits 100 and any solder
joints between them, and further protect the electrical circuits
100 during flexing of the coil assembly.
[0031] FIG. 4 shows a perspective view of the RF coil array 70 of
FIG. 2 having the modules 74-86 protectively covered. Each rib 90
includes a tent, or cover, 114 to shield the electrical circuits
100 and components 102 (FIG. 3) from contact with another object
that may disturb or dislodge the electrical circuits 100 and
components 102, which may cause an RF coil circuit to malfunction.
A basal support 116 surrounds and supports each column 88 of
modules 74-78, 82-86 and both columns 88 of module 80 such that the
RF coils 72 in each column 88 remain substantially planar as the
basal support 116 is rotated with respect to its neighbor. In one
embodiment, basal support 116 is constructed of a multi-layer
printed circuit board, and the RF coils 72 in each column 88 are
etched thereon. In another embodiment, the RF coils 72 in each
column 88 may be formed from loops of wire or electrical
conductors, and positioned within basal support 116.
[0032] Referring to FIG. 5, a side plan view of RF coil array 70 in
an unflexed position according to an embodiment of the present
invention is shown. As illustrated, each basal support 116 is
offset from its neighbors such that the RF coils 72 protected
therein are positioned substantially parallel to, but above and/or
below the RF coils 72 of neighboring basal supports 116. As shown
in FIG. 5, each module 74-86 is connected to its neighbor via a
hinge 120. In a preferred embodiment, hinge 120 is a piano hinge.
Alternatively, hinge 120 is a cam hinge system described below. It
is contemplated, however, that other suitable hinges, such a butt
hinge and the like, may also be used.
[0033] FIG. 6 shows a side plan view of RF coil array 70 in a
flexed position about an imaging object 118, such as a human torso,
according to an embodiment of the present invention. As shown, each
basal support 116 rotates with respect to adjacent supports 116
such that each column 88 of RF coils 72 remains in a substantially
planar state. Accordingly, flexing of the RF coil array 70 allows
the RF coil array 70 to follow the contour of the imaging object
118 while the RF coils 72 of each module 74-86 are rigidly
supported such that flex stresses on each RF coil 72 is
minimized.
[0034] FIG. 7 shows an RF coil displacement diagram 122
illustrating coil displacement curves 124, 126 of the amount of
coil overlap versus tilt, or rotation, angle of the basal supports
116 to achieve a minimum inductance between nearest-neighbor RF
coil columns 88. The mutual inductance between nearest-neighbor RF
coil columns 88 may remain constant or may vary between rotation
angles based on the geometry of the RF coil array 70. Coil
displacement curve 124 shows that the amount of overlap, in one
geometry, remains substantially constant as the tilt angle between
nearest-neighbor basal supports 116 varies. As such, a
non-translating hinge, such as hinge 120, may be used to
interconnect nearest-neighbor basal supports 116. However, coil
displacement curve 126 shows that the amount of overlap, in another
geometry, must change as the tilt angle between nearest-neighbor
basal supports 116 varies such that the mutual inductance between
nearest-neighbor RF coil columns 88 may be minimized.
[0035] FIG. 8 shows a side schematic diagram of a pair of RF coil
columns 128, 130 showing rotation and translation of one column 130
with respect to the other column 128. RF coil columns 128, 130 are
partially overlapped, as indicated by arrows 132, and spaced apart,
or distanced, as indicated by arrows 134, as discussed above, to
minimize mutual inductance therebetween. In a parallel arrangement
of RF coil columns 128, 130, respective axes 136, 138, orthogonal
to a plane of the RF coil columns 128, 130, are also in parallel.
As indicated by coil displacement curve 126 of FIG. 7, as the tilt
140 angle between RF coil columns 128, 130 varies, a translation of
RF coil column 128 relative to RF coil column 130 occurs such that
the amount of overlap 132 changes. In this manner, the mutual
inductance between RF coil columns 128, 130 during rotation may be
kept at a minimum. Preferably, the distance 134 between RF coil
columns 128, 130 remains constant during rotation. However, it is
contemplated that the distance 134 may vary in combination with the
amount of overlap 132 to minimize the mutual inductance between RF
coil columns 128, 130 during rotation.
[0036] FIG. 9 shows a perspective view of a cam hinge system 142 in
accordance with an embodiment of the present invention capable of
translating RF coil columns 128, 130 as described above with
respect to FIG. 8. The cam hinge system 142 includes a cam 144
configured to be connected to one basal support 116 and a cam
follower 146 configured to be connected to a neighboring basal
support 116. In a preferred embodiment, cam follower 146 includes a
pair of arms 148 having sliding contact surfaces 150 that slidingly
engage sliding contact surfaces 152 of cam 144. Further, cam
follower 146 preferably includes a pair of tongues 154 extending
from the pair of arms 148 into a groove 156 formed in cam 144. The
pair of tongues 154 and the groove 156 form a guide system that
maintains a constant lateral position of the one basal support 116
to the other basal support 116 in a lateral direction 158.
[0037] Cam 144 and cam follower 146 each further include a knob 160
extending in a same direction such that an elastic member 162, such
as a spring, a rubber band, and the like, interconnects the knobs
160 together to maintain engagement of the sliding contact surfaces
150, 152 to each other. In a preferred embodiment, the knob 160 of
cam 144 is concentric with an axis of rotation 164 of cam 144. In
this manner, as the cam 144 and cam follower 146 rotate with
respect to each other, the sliding contact surfaces 152 of cam 144
cause translation of the knobs 160 with respect to each other, and
hence, the respective basal supports 116 connected thereto, along a
translation direction 166. In a preferred embodiment, a pair of cam
hinge systems 142 rotatably interconnects each pair of neighboring
basal supports 116 of modules 74-86.
[0038] The cam hinge system 142 is designed such that displacement
of the cam 144 and cam follower 146 causes translational
displacement of neighboring RF coil columns 128, 130 according to a
desired displacement curve, such as the displacement curve 126 of
FIG. 7. As shown in FIGS. 8 and 9, cam 144 is oval. It is
contemplated, however, that the shape of cam 144 and the position
of the pair of arms 148 of cam follower 146 may vary from that
shown such that translation of the RF coil columns 128, 130 during
rotation follows the desired displacement curve.
[0039] FIG. 10 shows a schematic diagram of an RF coil array 168
according to another embodiment of the present invention. RF coil
array 168 includes a plurality of RF coils 170 positioned relative
to each other such that a mutual inductance between each
nearest-neighbor coil 170 is minimized. Preferably, the mutual
inductance between coils 170 is zero.
[0040] RF coil array 168 includes a plurality of supports 172-184
rotatably interconnected to each other. Each support 172-184 has a
column 186 of overlapping RF coils 170 attached thereto. In
addition, each support 172-184 includes a rib assembly 192 and a
pair of end members or links 194 attached to ends 188, 190 of the
rib 194. Ribs 192 are constructed in a manner similar to that
described above with respect to FIG. 3. Links 194 are preferably
constructed of a lightweight and sturdy material to increase
patient comfort and durability, such as ULTEM.RTM., polycarbonates,
or other suitable materials. ULTEM.RTM. is a registered trademark
of General Electric Company of Schenectady, N.Y.
[0041] A base housing 198 surrounds each column 186 of overlapping
RF coils 170. The base housing 198 provides additional structural
support, protects each column 186 of overlapping RF coils 170 from
repeated flexing, and protects a patient from coming into contact
with any of the coils 170.
[0042] An end connector 200 connects to an end 190 of each support
172-184. Each end connector 200 has a passage 202 therethrough such
that wires 204 connected to the RF coils 170 and electrical
circuits 100 (FIG. 3) may be routed through the end connector
200.
[0043] Referring to FIG. 11, a side plan view of RF coil array 168
in an unflexed position according to an embodiment of the present
invention is shown. As illustrated, each column 186 of overlapping
RF coils 170 is offset from its neighbors such that the RF coils
170 in each column 186 are positioned substantially parallel to,
but above and/or below the columns 186 of RF coils 170 of its
neighbors. Each pair of links 194 rotatably connects to an adjacent
pair of links 194 with a hinge system as described above.
[0044] FIG. 12 shows a side plan view of RF coil array 168 in a
flexed position about an imaging object 210, such as a human torso,
according to an embodiment of the present invention. As shown, each
supports 172-184 rotates with respect to adjacent supports 172-184
such that each column 186 of RF coils 170 remains in an unflexed
state. Accordingly, flexing of the RF coil array 168 allows the RF
coil array 168 to follow the contour of the imaging object 210
while minimizing flex stresses on the RF coils 170.
[0045] An RF coil array constructed according to the present
invention allows the array to flex about an axis axial to a subject
of interest. In this manner, the RF coil array may be wrapped
around at least a portion of the subject of interest, such as a
human torso or extremity. The array constructed according to the
present invention provides protection to RF coils and their
supporting electrical components such that repeated flexing of the
RF coils and components themselves is minimized.
[0046] Therefore, according to an embodiment of the present
invention, an MRI apparatus includes a magnetic resonance imaging
(MRI) system having a plurality of gradient coils positioned about
a bore of a magnet to impress spatially dependent changes to a
polarizing magnetic field and an RF transceiver system and an RF
switch controlled by a pulse module to transmit RF magnetic fields
from an RF transmit coil to excite MR signals and to acquire MR
signals using an RF receiver coil assembly to create MR images. The
RF coil assembly includes a pair of RF coil modules. Each RF coil
module includes a set of overlapping RF coils and a housing rigidly
supporting the set of overlapping RF coils. The RF coil assembly
includes at least one hinge connected to each of the pair of RF
coil modules and configured to permit the pair of RF coil modules
to rotate between an unflexed position and a flexed position.
[0047] According to another embodiment of the present invention, an
RF coil assembly includes a plurality of RF coil sets. The assembly
also includes a plurality of RF coil modules rotatably
interconnected to each other, each RF coil module rigidly connected
to one of the plurality of RF coil sets and configured to rotate
with respect to at least one adjoining RF coil module.
[0048] According to a further embodiment of the present invention,
a method of making an RF coil array includes connecting a first
plurality of RF coils to a first rigid support and connecting a
second plurality of RF coils to a second rigid support. The method
also includes attaching at least one hinge between the first and
second rigid supports.
[0049] The present invention has been described in terms of the
preferred embodiment, and it is recognized that equivalents,
alternatives, and modifications, aside from those expressly stated,
are possible and within the scope of the appending claims.
* * * * *