MR Findings of the Osteofibrous Dysplasia

OBJECTIVE: The aim of this study was to describe MR findings of osteofibrous dysplasia. MATERIALS AND METHODS: MR images of 24 pathologically proven osteofibrous dysplasia cases were retrospectively analyzed for a signal intensity of the lesion, presence of intralesional fat signal, internal hypointense band, multilocular appearance, cortical expansion, intramedullary extension, cystic area, cortical breakage and extraosseous extension, abnormal signal from the adjacent bone marrow and soft tissue and patterns of contrast enhancement. RESULTS: All cases of osteofibrous dysplasia exhibited intermediate signal intensity on T1-weighted images. On T2-weighted images, 20 and 4 cases exhibited heterogeneously intermediate and high signal intensity, respectively. Intralesional fat was identified in 12% of the cases. Internal low-signal bands and multilocular appearance were observed in 91%. Cortical expansion was present in 58%. Intramedullary extension was present in all cases, and an entire intramedullary replacement was observed in 33%. Cortical breakage (n = 3) and extraosseous mass formation (n = 1) were observed in cases with pathologic fractures only. A cystic area was observed in one case. Among 21 cases without a pathologic fracture, abnormal signal intensity in the surrounding bone marrow and adjacent soft tissue was observed in 43% and 48%, respectively. All cases exhibited diffuse contrast enhancement. CONCLUSION: Osteofibrous dysplasia exhibited diverse imaging features ranging from lesions confined to the cortex to more aggressive lesions with complete intramedullary involvement or perilesional marrow edema.

Acute and Chronic Tears of Anterior Cruciate Ligament: Role of Gadolinium-enhanced MR Imaging

PURPOSE: To evaluate the efficacy of fat-suppressed gadolinium-enhanced MR imaging in differentiating acutefrom chronic ligament tears of anterior cruciate ligament. MATERIALS AND METHODS: MR images of 22 patients witharthroscopically proven complete tear of the anterior cruciate ligament were retrospectively reviewed. Theinterval between injury and MR examination was one day to seven years. When ligament tear was detected on MR imagewithe three months of injury, the case was considered acute;if detected after three months had elapsed, it wasjudged to be chronic. The extent of contrast enhancement was graded as 1, 2 or 3; grade 1, enhancement wasconfined to the expected ligament region; grade 2, enhancement extended to the joint capsule; grade 3, enhancementextended beyond the joint capsule. The grades of contrast enhancement correlated with the acute and chronic stagesof ligament tears. Associated bone bruise and/or adjacent soft tissue edema were also evaluated. RESULT: Among15 patients with acute ligament tear, nine (60%) showed grade 3 enhancement; among seven in whom tearing waschronic, four (57%) showed grade 1 enhancement. Bone bruising was present in 100% of acute tears (15/15) and 29%of chronic tears (2/7). Soft tissue edema was associated in 87% of acute tears (13/15) and 29% of chronic tears(2/7). CONCLUSION: Fat-suppressed gadolinium-enhanced MR imaging could help differentiate acute from chronictears of anterior cruciate ligament, as well as bone bruising and tissue edema.