Decision of Optimal Measurement Site for MR Quantification of the Muscle Atrophy and Fatty Degeneration in Patients with Rotator Cuff Tear using a 2-PD Technique [Presidential Award Proceedings]

Purpose : This study investigated the influence of measurement location on the quantitative values of fat fraction (FF) and cross-sectional area (CSA), and determined the appropriate slice location for evaluation of these muscular changes using a 2-point Dixon (2-PD) sequence. Methods : The magnetic resonance imaging (MRI) results of 100 patients with full-thickness rotator cuff tears were evaluated retrospectively. The patients were divided into four groups based on Cofield's classification. CSAs and FFs were measured at the most lateral oblique slice on a sagittal Y-view (CYV : Conventional Y-view) and at three greater depths proportional to the tear length (TL). Paired t-tests were used to compare the quantitative FF and CSA values between the CYV and other depths. We also calculated the predictive values of the maximum CSA of the supraspinatus from the CSA at the CYV, and compared the actual measurement values of the maximum CSA. Results : The FF values were highly correlated with the TL regardless of the measurement location. While the CSA at the CYV and the maximum CSA decreased with increasing TL, the CSA was highly variable depending on the TL and measurement location. There was a strong correlation between the predictive values and the actual measurement values of the maximum CSA (R＝0.74). Conclusions : The CYV could be an optimal measurement site to evaluate muscular degeneration even in patients with rotator cuff tears. The FF and CSA of the supraspinatus muscle at the CYV could be ideal and useful quantitative imaging biomarkers for the evaluation of muscular degeneration.