Glenoid lab rum: MR imaging with histologic correlation

PURPOSE: To document the histopathologic basis of altered intralabral and sublabral signal intensity on magnetic resonance (MR) images. MATERIALS AND METHODS: Ten fresh cadaveric shoulder specimens underwent transaxial MR imaging with T1-weighted, proton-densityweighted, and T2-weighted spin-echo; multiplanar gradient-recalled echo (MPGR); three-dimensional Fourier transform gradient-recalled echo (GRE); spoiled gradient-recalled echo (SPGR); and T1-weighted, fat-suppressed sequences before and after intraarticular injection of gadolinium. Shoulders were then frozen and transversely sectioned, and histologic analysis of the labrum was performed. RESULTS: Altered intralabral signal intensity correlated with fibrovascular tissue, mucoid or eosinophilic degeneration, calcification, ossification, synovial tissue, or combinations of these findings. A sublabral transitional band of intermediate signal intensity correlated with a transitional zone of fibrocartilage. CONCLUSION: There are several causes of altered intralabral signal intensity. A transitional fibrocartilaginous zone correlates with sublabral increased signal intensity. Intraarticular administration of gadolinium improves evaluation of the glenoid labrum.