Horizontal component of partial-thickness tears of rotator cuff: imaging characteristics and comparison of ABER view with oblique coronal view at MR arthrography initial results.

PURPOSE: To determine the characteristics of horizontal components of partial-thickness tears of the rotator cuff at magnetic resonance (MR) arthrography and to determine whether use of the abduction and external rotation (ABER) position improved detection of a horizontal component in partial-thickness tears.
MATERIALS AND METHODS: MR studies in 16 patients (mean age, 32 years) who had partial-thickness tear with a horizontal component were retrospectively evaluated. All 16 patients had undergone arthroscopic surgery. The depth and extent of the horizontal component were measured on MR images, and the presence or absence of articular surface tear was recorded. The characteristics of the horizontal component on ABER views were compared with those on oblique coronal views.
RESULTS: A horizontal component (24 lesions; one tendon involved in eight patients and two tendons involved in eight patients) was observed in 100% of the lesions on ABER views and in 21% of the lesions (n = 5) on oblique coronal images. The mean length of the horizontal components, measured on ABER views, was 1.9 cm (range, 0.6-4.5 cm). Thirteen (54%) of the 24 lesions were classified as grade I (<3 mm) in depth, four (17%) were classified as grade II (3-6 mm), and seven (29%) were classified as grade III (>6 mm). Articular separation sites with a flap lesion were visualized in 15 (62%) of 24 lesions on ABER views.
CONCLUSION: MR arthrography of the shoulder with patients in the ABER position may provide additional information in cases of partial-thickness tears of the rotator cuff with a horizontal component. Copyright RSNA, 2002