MR Quantification of the Fatty Fraction from T2*-corrected Dixon Fat/Water Separation Volume-interpolated Breathhold Examination (VIBE) in the Assessment of Muscle Atrophy in Rotator Cuff Tears

Rationale and Objectives: To assess the usefulness of T2*-corrected fat fraction (FF) map from volume-interpolated breathhold examination (VIBE) magnetic resonance (MR) sequence in patients with the rotator cuff pathology. Materials and Methods: The phantom study was performed to validate the FF maps. Eighty-nine shoulder MR arthrographies were analyzed: (1) divided into three groups namely tendinopathy/normal tendons, partial-thickness tears, and full-thickness tears, and (2) occupation ratio (OR) was measured for muscular atrophy. Uncorrected and T2*-corrected FF maps were reconstructed from the VIBE images. The Pearson correlation test was used to correlate the FFs with ORs. The FF and the OR were compared between groups using the Student t test. Results: T2*-corrected FF maps could provide a higher correlation than uncorrected FF maps. There were significantly negative correlations between the ORs and the FFs (P<.01). In the normal and the partial-thickness tear group, the OR did not show a significant difference, although the FF maps showed a significant difference (P<.01). Conclusions: This quantitative assessment of the T2*-corrected FF in the rotator cuff muscles was found to be reliable and correlated well with the ORs. The T2*-corrected FF maps could be used for more sophisticated assessments of the fat even in the partial-thickness tear.