U.S. patent application number 09/888613 was filed with the patent office on 2002-05-02 for expandable mri receiving coil.
This patent application is currently assigned to CARDIAC M.R.I. INC.. Invention is credited to Badimon, Juan J., Fayad, Zahi A., Fuster, Valentin, Minkoff, Lawrence A., Shinnar, Meir.
Application Number | 20020050819 09/888613 |
Document ID | / |
Family ID | 22325105 |
Filed Date | 2002-05-02 |
United States Patent
Application |
20020050819 |
Kind Code |
A1 |
Minkoff, Lawrence A. ; et
al. |
May 2, 2002 |
Expandable MRI receiving coil
Abstract
A magnetic resonance image receiving coil includes a first
balloon having a longitudinal axis. An internal surface of the
first balloon defines an internal inflatable chamber. A second
balloon has a longitudinal axis. The second balloon is disposed
about the first balloon. A plurality of longitudinally extending
grooves are disposed in one of an external surface of the first
balloon and the internal surface of the second balloon. A first
wire is disposed in at least one of the grooves. A second wire is
disposed in at least a second one of the grooves. Each of the first
wire and the second wire is adapted to be electrically connected to
an MRI apparatus. In accordance with an alternate embodiment, the
first and second wires are disposed in grooves in a sheath which is
disposed between the first and second balloons. In accordance with
a further alternate embodiment, the first and second wires are
disposed in guide tubes that are connected to the external surface
of a balloon.
Inventors: |
Minkoff, Lawrence A.;
(Lattingtown, NY) ; Fuster, Valentin; (New York,
NY) ; Shinnar, Meir; (Teaneck, NJ) ; Fayad,
Zahi A.; (New York, NY) ; Badimon, Juan J.;
(Larchmont, NY) |
Correspondence
Address: |
DARBY & DARBY P.C.
805 Third Avenue
New York
NY
10022
US
|
Assignee: |
CARDIAC M.R.I. INC.
|
Family ID: |
22325105 |
Appl. No.: |
09/888613 |
Filed: |
June 25, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09888613 |
Jun 25, 2001 |
|
|
|
09442666 |
Nov 18, 1999 |
|
|
|
60108968 |
Nov 18, 1998 |
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Current U.S.
Class: |
324/318 ;
324/322 |
Current CPC
Class: |
G01R 33/34046 20130101;
A61B 5/055 20130101; G01R 33/34084 20130101; G01R 33/341
20130101 |
Class at
Publication: |
324/318 ;
324/322 |
International
Class: |
G01V 003/00 |
Claims
What is claimed is:
1. A magnetic resonance image receiving coil comprising: a first
balloon having a longitudinal axis, an internal surface of said
first balloon defining an internal inflatable chamber; a second
balloon having a longitudinal axis, said second balloon being
disposed about said first balloon; a plurality of longitudinally
extending grooves, said grooves being disposed in one of an
external surface of said first balloon and an internal surface of
said second balloon; a first wire disposed in at least one of said
grooves; and a second wire disposed in at least a second one of
said grooves, each of said first wire and said second wire having
means for being electrically connected to an MRI apparatus.
2. The magnetic resonance image receiving coil in accordance with
claim 1, wherein said plurality of grooves include four grooves
that are disposed at approximately 90.degree. intervals so that a
first pair of said grooves are disposed generally diametrically
opposite one another and a second pair of said grooves are disposed
generally diametrically opposite one another.
3. The magnetic resonance image receiving coil in accordance with
claim 2, wherein said first wire is disposed in said first pair of
said grooves.
4. The magnetic resonance image receiving coil in accordance with
claim 3, wherein said second wire is disposed in said second pair
of said grooves.
5. The magnetic resonance image receiving coil in accordance with
claim 4, wherein said wires are fixedly connected to said
grooves.
6. The magnetic resonance image receiving coil in accordance with
claim 5, wherein said wires are glued within said grooves.
7. The magnetic resonance image receiving coil in accordance with
claim 5, wherein said grooves are disposed in said external surface
of said first balloon.
8. The magnetic resonance image receiving coil in accordance with
claim 5, wherein said grooves are disposed in said internal surface
of said second balloon.
9. The magnetic resonance image receiving coil in accordance with
claim 7, wherein an elastic shaft is disposed within said first
balloon.
10. The magnetic resonance image receiving coil in accordance with
claim 8, wherein an elastic shaft is disposed within said first
balloon.
11. The magnetic resonance image receiving coil in accordance with
claim 1, wherein said first and second wires are coaxial cable.
12. The magnetic resonance image receiving coil in accordance with
claim 11, wherein each of said first and second wires are connected
to a tuning capacitor in a parallel circuit.
13. The magnetic resonance image receiving coil in accordance with
claim 11, wherein each of said first and second wires are connected
to a tuning capacitor in a parallel circuit.
14. A magnetic resonance image receiving coil comprising: a first
balloon having a longitudinal axis, an internal surface of said
first balloon defining an internal inflatable chamber; a second
balloon having a longitudinal axis, said second balloon being
disposed about said first balloon; a sheath being disposed between
said first balloon and said second balloon, said sheath having an
internal surface and an external surface; a plurality of
longitudinally extending grooves, said grooves being disposed in
one of said internal surface and said external surface of said
sheath; a first wire disposed in at least one of said grooves; and
a second wire disposed in at least a second one of said grooves,
each of said first wire and said second wire having means for being
electrically connected to an MRI apparatus.
15. The magnetic resonance image receiving coil in accordance with
claim 14, wherein said plurality of grooves include four grooves
that are disposed at approximately 90.degree. intervals so that a
first pair of said grooves are disposed generally diametrically
opposite one another and a second pair of said grooves are disposed
generally diametrically opposite one another.
16. The magnetic resonance image receiving coil in accordance with
claim 15, wherein said first wire is disposed in said first pair of
said grooves.
17. The magnetic resonance image receiving coil in accordance with
claim 16, wherein said second wire is disposed in said second pair
of said grooves.
18. The magnetic resonance image receiving coil in accordance with
claim 19, wherein said wires are fixedly connected to said
grooves.
19. The magnetic resonance image receiving coil in accordance with
claim 18, wherein said wires are glued within said grooves.
20. The magnetic resonance image receiving coil in accordance with
claim 18, wherein said grooves are disposed in said external
surface of said sheath.
21. The magnetic resonance image receiving coil in accordance with
claim 18, wherein said grooves are disposed in said internal
surface of said sheath.
22. The magnetic resonance image receiving coil in accordance with
claim 20, wherein an elastic shaft is disposed within said
sheath.
23. The magnetic resonance image receiving coil in accordance with
claim 21, wherein an elastic shaft is disposed within said first
balloon.
24. The magnetic resonance image receiving coil in accordance with
claim 14, wherein said first and second wires are coaxial
cable.
25. The magnetic resonance image receiving coil in accordance with
claim 24, wherein each of said first and second wires are connected
to a tuning capacitor in a parallel circuit.
26. The magnetic resonance image receiving coil in accordance with
claim 24, wherein each of said first and second wires are connected
to a tuning capacitor in a parallel circuit.
27. A magnetic resonance image receiving coil comprising: a first
balloon having an internal surface, an external surface and a
longitudinal axis, said internal surface of said first balloon
defining an internal inflatable chamber; a plurality of guide tubes
being connected to said external surface of said first balloon; a
first wire disposed in at least one of said guide tubes; and a
second wire disposed in at least a second one of said guide tubes,
each of said first wire and said second wire having means for being
electrically connected to an MRI apparatus.
28. The magnetic resonance image receiving coil in accordance with
claim 27, wherein said plurality of guide tubes include two guide
tubes that are disposed at approximately 90.degree. intervals with
respect to each other.
29. The magnetic resonance image receiving coil in accordance with
claim 27, wherein an elastic shaft is disposed within said first
balloon.
30. The magnetic resonance image receiving coil in accordance with
claim 28, wherein an elastic shaft is disposed within said first
balloon.
31. The magnetic resonance image receiving coil in accordance with
claim 27, wherein said first and second wires are coaxial
cable.
32. The magnetic resonance image receiving coil in accordance with
claim 31, wherein each of said first and second wires are connected
to a tuning capacitor in a parallel circuit.
33. The magnetic resonance image receiving coil in accordance with
claim 31, wherein each of said first and second wires are connected
to a tuning capacitor in a parallel circuit.
Description
EXPANDABLE MRI RECEIVING COIL
[0001] This is a continuation of application Ser. No. 09/442,666,
filed Nov. 18, 1999, now pending; which claims priority from
Provisional Application Serial No.: 60/108,968, filed Nov. 18,
1998, which is now expired. Each of these prior applications is
hereby incorporated herein by reference, in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an expandable MRI receiving
coil. More specifically, the present invention relates to an
expandable internal MRI receiving coil that has a first wire loop
and a second wire loop, such that the plane of the first wire loop
is positioned 90.degree. from the plane of the second wire loop to
produce a signal that is 90.degree. out of phase with respect to
the signal produced by the second wire loop.
[0004] 2. Discussion of the Related Art
[0005] Currently there are over 1.2 million angiography procedures
performed annually in the United States. These procedures are
performed to provide images of the cardiac system to physicians.
But traditional X-ray angiography will only provide a physician
with information regarding blood flow, and the amount of an
occlusion in the vessel. Moreover, the reasons for an occlusion may
not be apparent because no information regarding the underlying
biochemistry of the occlusion is provided by these conventional
techniques.
[0006] Magnetic resonance imaging is based on the chemistry of the
observed tissue. Therefore, MRI provides not only more detailed
information of the structures being imaged, but also provides
information on the chemistry of the imaged structures. For example,
most heart attacks occur in vessels that are less than 50% occluded
with plaque. But there are different types of plaque. One type of
plaque is very stable and is not likely to cause problems. However,
another type of plaque is unstable, if it becomes pitted or rough
it is possible for blood to clot and occlude the vessel. These
different types of plaque that are contained within the blood
vessels can be identified by MRI as has been described, for
example, by J. F. Toussaint et al., Circulation, Vol. 94, pp.
932-938 (1996). Conventionally, MR imaging of the heart has been
achieved with the use of a body coil (i.e., a receiving coil that
completely surrounds the torso) and specialized surface coils
designed for cardiac use. However, an external body coil provides a
relatively low signal to noise (SNR) when the object to be imaged
is small and distant from the coil as is the heart (especially the
rear portion thereof) and the aorta. Surface coils do increase the
SNR in those regions close to the coil, but not to those at any
distance from the coil.
[0007] Thus, in producing an MR image, it is desirable to increase
the SNR as much as possible. As a general rule, the closer the
receiving coil is to the object to be imaged, the better the SNR
will be. Thus, to produce an image of the heart and/or the aorta,
it is preferable to place a receiving coil within the body (i.e.,
an internal receiving coil). Additionally, for internal receiving
coils, the larger the diameter of the receiving coil, the larger
its area will be thereby improving its SNR.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to obtain an MR
image of an object deep within the body having a relatively high
SNR. This is accomplished by using a receiving coil that can be
passed through the esophagus into a position adjacent to the heart
and its surrounding vessels so that an MR image of the heart, the
aortic arch and the other major vessels of the heart can be made.
The receiving coil has a pair of loops that are oriented 90.degree.
relative to each other so that their respective signals are
90.degree. out of phase and the resultant combined image from these
signals will be more symmetrical.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
[0009] The above and still further objects, features and advantages
of the present invention will become apparent upon consideration of
the following detailed description of a specific embodiment
thereof, especially when taken in conjunction with the accompanying
drawings wherein like reference numerals in the various figures are
utilized to designate like components, and wherein:
[0010] FIG. 1 is a partial perspective view of an expandable MRI
balloon receiving coil in accordance with the present
invention;
[0011] FIG. 2A is a cross-sectional view of one embodiment of the
present invention, taken along line 2-2 of FIG. 1 and looking in
the direction of the arrows;
[0012] FIG. 2B is a cross-sectional view of another embodiment of
the present invention, taken along line 2-2 of FIG. 1 and looking
in the direction of the arrows;
[0013] FIG. 2C is a cross-sectional view of yet another embodiment
of the present invention, taken along line 2-2 of FIG. 1 and
looking in the direction of the arrows;
[0014] FIG. 2D is a cross-sectional view of another embodiment of
the present invention, taken along line 2-2 of FIG. 1 and looking
in the direction of the arrows;
[0015] FIG. 3 is a schematic illustration of the wires in the form
of two loops of coaxial cable connected in series with a tuning
capacitor;
[0016] FIG. 4 is a schematic illustration of the wires in the form
of two loops of coaxial cable connected in parallel with a tuning
capacitor;
[0017] FIG. 5 is a cross-sectional view of the MRI probe showing
only one coil, its tuning capacitor, central shaft, and the
internal and external balloons;
[0018] FIG. 6 is a perspective view of the internal balloon and the
wire loops in quadrature; and
[0019] FIG. 7 is a view of two wire loops shown in quadrature,
without the central shaft, internal and external balloon.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0020] Referring now to FIG. 1, a partial perspective view of an
MRI probe 10 is illustrated. Probe 10 includes an inner balloon 12
and an outer balloon 14.
[0021] In a first embodiment, which is illustrated in FIG. 2A,
balloon 12 has four axially extending grooves 16, 18, 20 and 22 in
its outer surface. Groove 16 is disposed generally diametrically
opposite from groove 20. Likewise, groove 18 is disposed generally
diametrically opposite from groove 22. Thus, adjacent grooves are
disposed at 90.degree. intervals. At the distal end 24 of inner
balloon 12, grooves 16, 18, 20, 22 curve radially inwardly and
intersect at the distal tip or apex 26 of inner balloon 12. Thus,
as viewed from the front, grooves 16, 18, 20 and 22 appear to
intersect at 90.degree. angles, thereby resembling cross hairs. A
first wire 28 is placed within grooves 16, 20. A second wire 30 is
placed within grooves 18, 22. Wires 28, 30 are insulated from one
another at least at their point of intersection at distal tip 26.
Wires 28, 30 are fixedly held within grooves 16, 20, 18 and 22. In
a currently preferred embodiment, wires 28, 30 are glued within
their respective grooves 16, 20 and 18, 22, respectively.
[0022] A shaft 32 is disposed within inner balloon 12. If shaft 32
is used, it is preferably a plastic tube of appropriate size and is
formed from an elastic material that has sufficient flexibility to
allow probe 10 to enter the human body through either the mouth or
nose and, thereafter, be placed within the esophagus. Shaft 32
preferably has an outer diameter of less than {fraction (3/16")} if
it is to enter into the mouth and less than {fraction (1/4")} if is
to be inserted into the nose. An annular space 34 is disposed
between shaft 32 and inner balloon 12. Annular space 34 is, at its
proximal end, fluidly connected to a conduit (not shown), which is
connected to a source of fluid pressure to selectively inflate and
deflate the inner balloon as desired. Additionally, as those
skilled in the art will readily recognize, wires 28, 30 form two
loops that are electrically connected at their proximal end via
interface circuits for impendence matching (not shown). The
interface circuits are then electrically connected to a
conventional MRI apparatus (e.g., an MRI spectrometer) to produce
an image based upon a signal received by wires 28, 30.
[0023] Wires loops 28, 30 are preferably each formed from coaxial
cable that may be connected to a tuning capacitor 60 either as
shown in FIG. 3 in a series circuit or as shown in FIG. 4 in a
parallel circuit. In the currently preferred embodiment, the
parallel circuit is used because it provides at least twice the SNR
of a series circuit. In any of the below embodiments, wire loops
28, 30 are each preferably formed from coaxial cable, which has an
outer conductor 70 and an inner conductor 71. For both wire loops
28, 30, the approximate midpoints of the outer conductor 70 has a
gap 75. While gap 75 is provided at or near the point of
intersection of wires 28, 30, the wires are still insulated from
one another. Wires 28, 30 are disposed at approximately 90.degree.
intervals. Thus, the signal produced by wire 28 and 30 are said to
be in quadrature. Therefore, the resulting image produced from the
signals received from wires 28, 30 is more symmetrical than a
conventional receiving coil. The MRI apparatus can be, for example,
a GE Signa, 1.5 Tesla, which is commercially available from General
Electric Company.
[0024] In operation, the probe 10 is initially in a deflated state
and the outer surface of outer balloon 14 is preferably well
lubricated with a conventional, sterile, water-soluable lubricant.
The distal end 24 of the probe is then inserted into the body
through either the mouth or the nose. Distal end 24 is further
inserted into the body until it passes into the esophagus. The
receiving coil is placed in the desired position within the
esophagus, as close to the object to be imaged as possible. For
example, for the closest approach to the heart and the aortic arch,
the receiver coil should be placed within the esophagus behind and
under the heart and the aortic arch. The balloon assembly is
inflated to maintain the position of the receiver coil within the
esophagus and so that the receiver coil will be as large in
diameter as possible without causing harm to the esophagus. Of
course, the amount that the balloon is inflated will vary from
patient to patient, but will typically will be on the order of
about {fraction (1/2)} inch in diameter by 5 inches in length when
inflated.
[0025] The receiving coil alone may be sufficient to obtain an
adequate image of the aortic arch. Alternatively, an external
surface MRI receiving coil may be placed on the patient to produce
a combined image from the internal probe 10 and the external
receiving coil (not shown). A method of generating a combined image
of the heart and the vessels emanating from the heart, from the
combination of a first image from a coil placed within the body and
a second image from a coil placed externally to the body is
disclosed in Applicants' copending application Ser. No. 09/081,908,
entitled "Cardiac MRI With An Internal Receiving Coil and An
External Receiving Coil", filed on May 20, 1998, the disclosure of
which is hereby fully incorporated by reference.
[0026] Referring now to FIG. 2B, an alternate embodiment of probe
10' is illustrated. In this embodiment, an intermediate tubular
sheath 36 is disposed between inner balloon 12 and outer balloon
14. Sheath 36 is formed with grooves 38, 40, 42, 44 to receive
wires 28, 30. Sheath 36 is made from an elastic material, such as,
for example, latex, to permit tubular sheath 36 to expand when
inner balloon 14 is inflated once the probe has been placed in the
esophagus.
[0027] Referring now to FIG. 2C, a further alternate embodiment of
probe 10" is illustrated. In this embodiment, a plurality of guide
tubes 46, 48 are placed on the exterior surface of balloon 12. Each
guide tube extends about the closed distal end 24 of balloon 12.
Thus, each guide tube has a first portion that is disposed on one
external side of balloon 12 and a second portion that is disposed
on a generally diametrically opposite external side of balloon 12.
Wire 28 is inserted into guide tube 46. Similarly, wire 30 is
placed within guide tube 48. Thus, when probe 10" is placed within
the esophagus, balloon 12 may be inflated to maintain the position
of wires 28, 30, which together form the receiving coil within the
esophagus so that the receiver coil will have as large a diameter
as possible without causing harm to the esophagus.
[0028] Referring now to FIG. 2D, a further alternative embodiment
of probe 10"' is illustrated. Grooves 50, 52, 54 and 56 are
disposed within the inner cylindrical surface of outer balloon 14.
Wire 28 is placed within grooves 50, 54. Similarly, wire 30 is
placed within grooves 52, 56. In use, probe 10"' operates in a
manner similar to the embodiments illustrated in FIGS. 2A, 2B and
2C. In other words, once the probe has been placed within the
esophagus, the annular space between shaft 32 and inner balloon 12
is inflated thereby causing the entire probe to stably maintain the
position of the receiving coil within the esophagus so that the
receiving coil has as large a diameter as possible without causing
harm to the esophagus. The receiving coil may then be used to
obtain an image of, for example, the heart and/or the aortic
arch.
[0029] Referring now to FIG. 5, a cross-sectional view of the MRI
probe 100 is illustrated. Here a single wire loop 128 or 130
(referred to as 128, 130 in FIG. 5) is illustrated inflated on
inner balloon 112. Both the wire loop and the inner balloon are
covered by the outer balloon 114. Both the inner and outer balloons
are subsequently attached at both ends to the central tubular shaft
132. Wire loop 128 or 130 also penetrates into the central tube 132
at both ends. At the proximal end, where the loop 128 or 130
penetrates into the central tube 132, the wire 128 or 130 continues
down through central shaft 132 and out of its proximal end to the
MRI spectrometer.
[0030] Referring now to FIG. 6, a perspective view of the wire
loops 28, 30 and inflated inner balloon 12 is illustrated. Wire
loops 28, 30 are shown in quadrature, with outer balloon 14 being
removed for the sake of clarity on the drawings. Referring now to
FIG. 7, only the wire loops 28, 30 are shown for the sake of
clarity. Wire loops 28, 30 are shown in quadrature.
[0031] Having described the presently preferred exemplary
embodiment of an expandable MRI receiving coil in accordance with
the present invention, it is believed that other modifications,
variations and changes will be suggested to those skilled in the
art in view of the teachings set forth herein. It is, therefore, to
be understood that all such modifications, variations, and changes
are believed to fall within the scope of the present invention as
defined by the appended claims.
* * * * *