RECEIVING SURFACE COIL FOR NUCLEAR MAGNETIC RESONANCE MEASUREMENTS

Abstract

For a receiving surface coil (1) for detecting nuclear magnetic resonance signals from a patient a solution for an easy adaption of the receiving surface coil (1) to the anatomy of the patient shall be created. This is achieved by a receiving surface coil (1) for detecting nuclear magnetic resonance signals from a patient, the receiving surface coil (1) comprising: a flexible housing (13) with an opening (2), a set of RF loop elements (8, 9) housed in the flexible housing (13), wherein the set of RF loop elements (8, 9) comprises at least a central loop (9) element running around the opening (2) in the flexible housing (13) and a plurality of loop elements (8) arranged around the opening (2).

Claims

1. A receiving surface coil for detecting nuclear magnetic resonance signals from a patient, the receiving surface coil comprising: a housing having a central part and at least two parts extending from the central part in opposite directions, wherein an opening is defined in the central part of the housing and the central part is configured to bend around the opening to form a shape that fits a patient anatomy to be examined; a set of RF loop elements housed in the central part of the housing, wherein the set of RF loop elements comprises at least a central loop element and more than two other loop elements which are arranged to increase central image duality with the central loop element running around the opening and the other loop elements arranged around and adjacent to the opening.

2. The receiving surface coil according to claim 1, wherein the receiving surface coil comprises at least one groove along a surface of the housing of the receiving surface coil and configured to guide a bending of the receiving surface coil.

3. The receiving surface coil according to claim 1, wherein the opening is configured to receive a protrusion of the patient anatomy.

4. The receiving surface coil according to claim 1, and a width of the at least two parts is less than the width of the central part, such that the at least two parts define opposite flaps of the central part.

5. The receiving surface coil according to claim 1, wherein the parts extending from the central part are subdivided by n grooves into a number of n+1 segments where n=1, 2, 3, . . . , which are joined to one another.

6. The receiving surface coil according to claim 2, wherein the grooves in the parts extending from the central part run perpendicular to the longitudinal axis of the receiving surface coil.

7. The receiving surface coil according to claim 1, wherein the receiving surface coil comprises at least two grooves in the central part, wherein the grooves in the central part are so arranged to cross each other in the opening of the central part when each groove is elongated along a longitudinal axis of the groove.

8. The receiving surface coil according to claim 1, wherein the more than two loop elements are arranged in an approximately circular array around the opening, wherein the more than two loop elements arranged around the opening overlap at least with the central loop element.

9. The receiving surface coil according to claim 8, wherein the set of RF loop elements comprises at least seven loop elements, the central loop element running around the opening in the central part and at least six further loop elements arranged around the opening in the central part, wherein every adjacent two of the six further loop elements overlap.

10. The receiving surface coil according to claim 2, comprising further electrical elements within the housing, wherein the further electrical elements are arranged in the housing in a region where the housing does not comprise grooves.

11. The receiving surface coil according to claim 10, wherein the further electrical elements are detuning circuit and/or feeding board.

12. The receiving surface coil according to claim 1, wherein the housing (13) comprises a foam.

13. The receiving surface coil according to claim 12, wherein the foam is mechanically flexible.

14. The receiving surface coil according to claim 1, wherein the opening is located at a center of the central part.

15. A magnetic resonance imaging system comprising a receiving surface coil for detecting nuclear magnetic resonance signals from a patient according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. Such an embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.

[0023] In the drawings:

[0024] FIG. 1 schematically depicts a receiving surface coil for detecting nuclear magnetic resonance signals from a patient according to a first embodiment of the invention,

[0025] FIG. 2 schematically depicts the receiving surface coil from the first embodiment, wherein the coil is bended along some grooves,

[0026] FIG. 3 shows exemplarily the application of the receiving surface coil on a human elbow,

[0027] FIG. 4 shows the distribution of loop elements within the receiving surface coil according to two embodiments of the invention,

[0028] FIG. 5 schematically depicts a receiving surface coil, wherein FIG. 5a depicts the distribution of electrical elements within the flexible housing of the receiving surface coil according to an embodiment of the invention and FIG. 5b depicts the distribution of grooves on the flexible housing of the receiving surface coil according to an embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0029] FIG. 1 schematically depicts a receiving surface coil 1 for detecting nuclear magnetic resonance signals from a patient according to a first embodiment of the invention. The receiving surface coil 1 described below can be e.g. a Flex M coil. The coil 1 comprises an outer surface and an inner surface, wherein the inner surface is placed over the patient for detecting the nuclear magnetic resonance signals from the patient. In an embodiment of the invention the receiving surface coil 1 comprises a flexible housing 13 with an opening 2 and a set of RF loop elements 8, 9 with at least a central loop element 9 running around the opening 2 and a plurality of other loop elements 8 centered around the opening 2. The flexible housing 13 can be round with the previously described arrangement of the loop elements 8, 9 in an embodiment of the invention.

[0030] The receiving surface coil 1 shown in FIG. 1 covers in an embodiment of the invention three parts 4, 5, 6. A central part 6 which, in a version of the invention, may have a round shape and at least two parts 4, 5 laterally adjoining the central part 6 extending from the central part 6 in opposite directions, such that the receiving surface coil 1 has an elongated extension along the longitudinal axis of the receiving surface coil 1. Thus, a larger coverage of the receiving surface coil 1 and a larger SNR can be achieved. In the embodiment of FIG. 1, a width of the at least two parts 4, 5 is less than the width of the central part 6, such that the at least two parts 4, 5 define opposite flaps of the central part 6. Narrower flaps facilitate the bending of the central part 6 around the opening 2 to form a shape that conform to the patient anatomy. Furthermore, additional loop elements 8 can be placed in the lateral parts 4, 5.

[0031] The central part 6 of the coil 1 includes an opening 2, which can have a round shape as shown in FIG. 1. However, other shapes of the opening 2 are also conceivable. For example, the opening 2 can have a star shape in another embodiment. The opening 2 ensures that the coil 1 can be placed as close as possible to the object to be examined, for example a knee or breast. The opening 2 also helps in positioning the coil 1, as it makes it easier to find the center of the coil 1.

[0032] The two parts 4, 5 laterally adjoining the central part 6 can be same length or for example can show different lengths. In FIG. 1 it is further shown that the two parts 4, 5 are interrupted by vertical grooves 3 that divide the two parts 4, 5 into individual segments 12. The grooves 3 form hinges that make it easier to bend the coil 1.

[0033] The central part 6 can also have several grooves 7. FIG. 1 shows an example where the grooves 7 run along the surface of the coil 1 in an X-shape and are arranged to intersect in the center of the opening 2 when each groove is elongated along a longitudinal axis of the groove. This makes it easier to bend the coil 1, especially in the central part 6 of the coil 1 and adapt it to the corresponding anatomy of a patient, for example. In addition to X-shaped grooves 7, however, a grid of grooves or a honeycomb structure of grooves can also be provided, for example, to facilitate bending of the coil 1. In one embodiment, the grooves 7 form many indentions along an inner surface of the coil 1. When the coil 1 is bended, the indentations on the inner surface are closed. The depth of the indentations is determined to ensure an easy bending but no intersection with the PCB board housed within the coil 1. Alternatively, both inner surface and outer surface of the coil 1 can be provided with the grooves 7 to realize a reversible coil, both sides of which can be placed over the patient anatomy to further facilitate the positioning.

[0034] The receiving surface coil 1 can be covered with a flexible foam in one version. It may be intended that the grooves 3, 7 run in the flexible foam to further facilitate bending of the coil 1.

[0035] FIG. 2 schematically depicts the receiving surface coil 1 from the first embodiment, wherein the coil 1 is bended along some grooves 3, 7. In FIG. 2 it can be seen, that the coil 1 can be easily bent around the opening 2 of the central part 6 due to the X-shaped grooves 7. This allows the coil 1 to be easily adapted to the corresponding anatomy of the patient. The lateral parts 4, 5 of the coil 1 can, for example, be placed around the part of the patient's body that is to be examined in order to further improve the resolution of the coil 1.

[0036] FIG. 3 shows exemplarily the application of the receiving surface coil 1 on a human elbow 11. In FIG. 3 a patient's arm 10 with the coil 1 placed around the patient's arm 10 at elbow level is shown. The elbow 11 can be exactly in the opening 2 of the coil 1, for example. The opening 2, the grooves 3, 7 and the flexible structure of the coil 1 allows the coil 1 to be easily placed around the patient's arm 10, thus increasing the image quality.

[0037] FIG. 4 shows the distribution of loop elements 8, 9 within the receiving surface coil 1 according to two embodiments of the invention. A receiving surface coil 1 mainly includes a set of RF loop elements 8, 9, detuning circuits, feed boards and cables. The set of RF loop elements 8, 9 detuning circuits and feed boards are located on a printed circuit board (PCB).

[0038] The loop elements 8, 9 resonate at a specific center frequency of MRI system. The detuning circuits are used to switch the coil 1 into tune or detune status. The cables route RF signals and control signals. The feed boards mainly include the independence match circuits for pre-amplifiers and direct current circuits for the coil 1. In an embodiment the pre-amplifiers are not placed on the coil PCB board, to make the coil lighter and more flexible. In an embodiment of the invention the detuning circuits, feed boards and/or other electrical elements are arranged in the flexible housing 13 in a region where the flexible housing 13 does not comprise grooves 3, whereby the detuning circuits, feed boards and/or other electrical elements undergo only a slight bending and are protected from a force added by bending of the receiving surface coil 1. The set of RF loop elements 8, 9 of the receiving surface coil 1 shown in FIG. 4 comprises in an embodiment of the invention seven or eight loop elements 8, 9. In FIG. 4 a) an embodiment of the invention with seven loop elements 8, 9 is shown. An approximate circular shaped loop element 9 is in the middle of the central part 6, with six loop elements 8 around. Every two loop elements 8 overlap to decouple, and most of the loop elements 8 contribute to the central part 6 as these loop elements 8 are arranged around and adjacent to the opening 2, which can improve the image quality in the central scan region. The receiving surface coil 1 in the embodiment with seven loop elements 8, 9 has a symmetrical shape and is e.g. good for dual coil usage. With the opening in other shapes, the loop elements 8 are arranged around and adjacent to the opening, resulting in a shape approximately following a curvature of the opening.

[0039] In FIG. 4 b) a receiving surface coil 1 with eight loop elements 8, 9 is shown. An approximate circular shaped loop element 9 is in the middle of the central part 6, with six loop elements 8 around. Also, with this embodiment every two loop elements 8 overlap to decouple, and most of the loop elements 8 contribute to the central part 6, which can also improve the image quality in the central scan region. In addition, the receiving surface coil 1 has an eighth loop element 8, which is also located in one of the parts 4, 5 laterally adjoining the central part 6. By simply combining two of these coils 1, high-resolution imaging such as NVA anterior, breast screening and knee scanning can be provided.

[0040] In FIG. 5a the distribution of further electrical elements 14, 15 within the flexible housing 13 of the receiving surface coil 1 according to an embodiment of the invention is shown. Especially the distribution of the loop elements 8, the central loop element 9, the detuning circuit 14 and the feed boards 15 can be seen. If one compares the distribution of the electrical elements 14, 15 shown in FIG. 5a with the distribution of the grooves 3 in the flexible housing 13 of the receiving surface coil 1 shown in FIG. 5b, it becomes apparent that, in particular in one embodiment of the invention, the detuning circuit 14 and the feed boards 15 are arranged in an area within the flexible housing 13 which does not comprise grooves 3. This means that the electrical elements 14, 15 are only slightly bent, as the bend is essentially along the grooves 3 and are therefore protected from a force added by bending of the receiving surface coil 1.

[0041] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope. Further, for the sake of clearness, not all elements in the drawings may have been supplied with reference signs.

REFERENCE SYMBOL LIST

[0042] receiving surface coil 1 [0043] opening 2 [0044] groove 3 [0045] first part 4 [0046] second part 5 [0047] central part 6 [0048] X-shaped grooves 7 [0049] loop element 8 [0050] central loop element 9 [0051] human arm 10 [0052] human elbow 11 [0053] segment 12 [0054] flexible housing 13 [0055] detuning circuit 14 [0056] feed board 15