Résumé
PURPOSE: To determine the usefulness of MR imaging for differentiation between infectious and non-infectiousbursitis. MATERIALS AND METHODS: MR images of 16 patients (18 lesions) in whom bursitis around the hip had beendiagnosed were analyzed for homogeneity of the bursa, the presence of septation, the enhancement pattern, andassociated findings. Clinical data (symptoms and signs, laboratory data, aspiration of the bursa, and surgicalfindings) were available for correlation. The location of bursitis was trochanteric (n=9), ischiogluteal (n=5),iliopsoas (n=3), or ischiotrochanteric (n=1). RESULTS: Etiologies included infection in seven cases (3 pyogenic; 4tuberculous) and noninfecti-on in 11 (6 inflammation; 3 hemorrhage; 2 metabolic disease). In seven patients withinfectious bursitis, T1-weighted enhanced image revealed thick rim enhancement of the bursa (n=7) association withchanges in bone marrow signal intensity (n=2), bone erosion (n=2), and cellulitis (n=1). Of 11 cases ofnoninfectious bursitis, three demonstrated typical signal characte-ristics of hematoma within the distended bursa.In six of seven patients who underwent contrast-enh ancement, thick and thin peripheral enhancement of the bursawas noted. Bone erosion was found in one case of tuberculous bursitis and two of metab-olic disease. Internalseptation (n=4) and internal debris (n=3) were found in both infected and noninfected patients. CONCLUSION: MRimaging plays an important role in the diagnosis of bursitis around the hip. MR findings of thick rim enhancement,associated cellulitis, and changes in bone marrow signal intensity are suggestive of infectious bursitis.