Abstract:
A pillow, for supporting and fixing the shoulders of an examination subject in the respective housings of different shoulder coils in a magnetic resonance apparatus, snugly fills the inner area of the shoulder coil with at least three, and preferably four lobes with the lobes not laterally overlapping one another.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention concerns a pillow for supporting and fixing the shoulders of an examination subject in the housing of a shoulder coil in a magnetic resonance apparatus. 
         [0003]    2. Description of the Prior Art 
         [0004]    In magnetic resonance data acquisitions, the shoulders of the subject must be supported and fixed comfortably. Furthermore it is important for a specific distance to be maintained between the inner surface of a shoulder coil and the shoulders, in order to minimize unwanted signals that originate from the subcutaneous fat layer of the shoulders. There have previously been no standardized, commercially produced solutions in order to satisfy the above conditions. Makeshift solutions such as hand towels or foam padding that were not tailored to the shape of the inner surface of the shoulder coil have been used. 
         [0005]    The problem is thus that the aforementioned makeshift solutions do not represent uniform, reproducible devices in order to fix the shoulders at a fixed, optimal distance from the inner surface of the shoulder coil. 
       SUMMARY OF THE INVENTION 
       [0006]    An object of the present invention is to provide a device with which the shoulders of a patient can be comfortably supported, fixed and held at a fixed distance from the inner surface of the shoulder coil during a magnetic resonance acquisition. 
         [0007]    The above object is achieved in accordance with the invention by a pillow for supporting and fixing the shoulders in the housings of shoulder coils in magnetic resonance apparatuses, that snugly fills the inner area of the shoulder coil with at least three, and preferably four lobes, with and the lobes not laterally overlapping each other in the housing. 
         [0008]    The present invention is advantageous for a number of reasons. The basis of the invention is a pillow that enables the comfortable support of the shoulders of patients at a fixed distance from the inner side of the shoulder coil of a magnetic resonance system. The pillow has a unit size that fits all shoulder coil sizes and shoulder sizes. The pillow is thus universally usable and can be industrially produced in a large quantity and in a uniform shape size. Furthermore, the pillow exhibits a good filling factor due to its structure composed of a number of lobes. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The single FIGURE is a schematic depiction of a pillow in accordance with the invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0010]      FIG. 1  shows an exemplary embodiment of the present invention, namely a pillow  1  for supporting and fixing of the shoulders of a subject in housings of shoulder coils in magnetic resonance apparatuses. 
         [0011]    A shoulder coil for which the inventive pillow  1  used has a housing in which, for example, four coil elements are contained that are designed as flat copper conductive traces in the form of ovals. Magnetic resonance signals can be detected therewith with high spatial resolution. The housing ensures that a minimum distance is maintained between the (for example four) elements of the shoulder coil and the shoulder surface, which prevents an unwanted heating of the shoulder to be examined. The shoulder coil is fastened in a fixed manner on the patient table (bed) that is slid into the opening of the magnetic resonance system for the examination (data acquisition). Depending on whether the right or left shoulder is to be examined, there are various positions in which the shoulder coil can be placed on a base plate that in turn rests on the patient table. In order to acquire an optimally good signal from the shoulder regions to be examined and to comfortably support the shoulders, a spacer can additionally be provided between the inner surface of the shoulder coil and the shoulder of the patient. The pillow  1  is designed to serve such a spacer. 
         [0012]    The pillow  1  is provided with at least three, and preferably four, lobes  2  that snugly fill the inner area of the shoulder coil. The lobes  2  do not laterally overlap after the pillow  1  is placed in the shoulder coil. 
         [0013]    In the version of the pillow  1  with four lobes  2 , these are arranged in the form of a four-leaf clover. V-shaped openings  3  are respectively punched out between the lobes  2 . These openings  3  ensure that the lobes  2  of the pillow  1  do not laterally overlap after the placement of the pillow  1  in the shoulder coil. 
         [0014]    The pillow  1  can exhibit a thickness of 5 mm through 25 mm and advantageously 12 mm in order to provide the desired large distance between the inner surface of the shoulder coil and the shoulder that signals from the subcutaneous fat layer of the shoulder are largely suppressed. These signals are undesirable because they overlap the relevant signals from fluids or cartilage of the shoulder and adulterate the acquired signals. A value must be found for the thickness of the pillow  1  for which the signals from the fat layer are sufficiently small but the desired signals (which likewise decrease given increasing distance of the shoulder from the shoulder coil) are still large enough to yield a sufficiently strong signal at a given signal/noise ratio. 
         [0015]    Furthermore, it is important that the material for the pillow  1  not be image-producing (i.e., it should not make a contribution to the result MR image). The pillow  1  should be invisible or generate no artifacts in the magnetic resonance images. The pillow  1  must additionally be formed of material that is biocompatible, thus does not aggravate or harm the patient. 
         [0016]    The pillow  1  can be formed of a number of elastic materials. Foams (such as, for example, foamed material) can advantageously be used. A compromise between deformability and rigidity of the pillow  1  must be found in order to satisfy the concurrent requirements of comfortable support of the shoulder and spacing of the shoulder from the shoulder coil at an approximately fixed value. 
         [0017]    The foamed pillow  1  can be covered by a lacquer layer or a film that protects the pillow  1  against abrasion and makes the cleaning of the pillow  1  easier. 
         [0018]    The pillow  1  must be formed as a single part in order to make the manufacturing process easier and to achieve a good matching shape without projecting edges in the inner area of the shoulder coil. 
         [0019]    Furthermore, the pillow  1  has a unit size that fits both in small shoulder coils with, for example, a 165 mm opening and in large shoulder coils with, for example, a 200 mm opening. Small shoulder coils are suitable for the majority of patients; large shoulder coils must only be used for very muscular or overweight patients. 
         [0020]    The pillow  1  can be loosely inserted between the inner side of the shoulder coil and the shoulder of the patient. It is attached neither to the shoulder coil nor to the shoulder. The slight pressure with which the shoulder is placed in the shoulder coil is sufficient to hold the pillow  1  in position. 
         [0021]    Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art.