Fibrous dysplasia: MR imaging characteristics with radiopathologic correlation.

Objective: The purpose of this study was to describe the findings of MR imaging of fibrous dysplasia and to evaluate the correlation between radiologic and pathologic findings.

Methods: MR images of 13 proven cases of fibrous dysplasia were analyzed for signal intensity, hypointense rind, internal septations, cystic changes, soft-tissue extension, and patterns of contrast enhancement.

Results: All cases of fibrous dysplasia showed low signal intensity on T1-weighted MR images. Five cases (38%) were hypointense on T2-weighted MR images, and the other eight cases (62%) were hyperintense. Hypointense rind was seen in 10 cases (77%); internal septations were seen in three cases (23%); and cystic changes was seen in two cases (15%). Soft-tissue extension was observed in four cases (31%), including one case (8%) with a pathologic fracture. After gadolinium infusion, central contrast enhancement was noted in eight cases (73%), and peripheral rim enhancement was noted in three cases (27%). Numerous bony trabeculae, confirmed pathologically, caused a hypointense signal intensity on T2-weighted images.

Conclusions: Patients with fibrous dysplasia showed a correlation between radiologic and pathologic findings. Our results showed that T1-weighted images reveal fibrous dysplasia as hypointense, and T2-weighted images reveal fibrous dysplasia as either hyperintense or hypointense. Signal intensity on T1- and T2-weighted images and the degree of contrast enhancement on T1-weighted images depended on the amount and degree of bony trabeculae, cellularity, collagen, and cystic and hemorrhagic changes.