抄録
Background: The purpose of this study was to determine the proper slice position for evaluation of muscle atrophy followed by rotator cuff tears.
Methods: Seventy-seven shoulders were arthroscopically evaluated for the presence and the size of the tear and included in this study. There were 14 shoulders with impingement syndrome (I), 14 small tears (S), 18 medium tears (M), 14 large tears (L), and 17 massive tears(MA). Data from preoperative MDCT after arthrography were analyzed by 3D image software. Oblique sagittal images were obtained and cross-sectional areas (CSAs) of supraspinatus (SSP), subscapularis (SSC), infrastupatus and teres minor (ISP+TM) were measured and muscle volumes were calculated.
Results: The position of the Y-shaped view was 16.8 mm medial from the glenoid surface. The volume of SSC and ISP+TM were not different, however, suprasupinatus muscle volume was significantly decreased in L and MA when compared to I. CSAs were maximal at 25 mm medial from the glenoid surface in SSP, 35mm in SCC, and 40mm in ISP+TM, respectively. The strongest correlation between muscle volume and CSAs was seen on 35 mm mediall to the glenoid surface in SSP, 40mm in SSC, and 55mm in ISP+TM.
Conclusion: Muscle atrophy occurred only in SSP when the size of the tear is larger than 30mm. The proper position for evaluating muscle atrophy is about 10 mm medial to the Y-shaped position for SSP. More medial slice is required for SSC and ISP+TM.
