MR-IMAGING OF THE NORMAL AND ABNORMAL RETROCALCANEAL BURSAE

OBJECTIVE, The aim of this study was to define the MR imaging criteria for normal and abnormal retrocalcaneal bursae. SUBJECTS AND METHODS. Fifty ankles in 25 asymptomatic volunteers and 30 ankles in patients w ith Achilles tendon disorders underwent MR imaging. Increased signal i ntensity consistent with fluid or synovium outlining the retrocalcanea l bursa was measured. RESULTS. Of 80 bursae, 77 (96%) had measurable f luid or synovial signal intensity revealed by MR imaging. Asymptomatic volunteers had average bursal dimensions of 1 mm in the anteroposteri or dimension, 6 mm in the transverse dimension, and 3 mm in the cranio caudal dimension. Bursal dimensions greater than 1 mm, 11 mm, or 7 mm, respectively, were not seen in asymptomatic subjects but were seen in 16 (53%) of 30 ankles of patients with Achilles tendon disorders. CON CLUSION. On MR imaging, the asymptomatic retrocalcaneal bursa normally contains detectable high-signal-intensity fluid or synovium or both. A bursa larger than 1 mm anteroposteriorly, 11 mm transversely, or 7 m m craniocaudally is abnormal.