MR Findings of Ossifying Fibroma with Pathologic Correlation

ABSTRACT

PURPOSE: To compare the MR imaging findings of ossifying fibroma with the histopathologic findings. MATERIALS AND METHODS: In eight patients (M:F=1:7; age range, 1-25 years) with pathologically proven ossifying fibroma, plain film and MR images were retrospectively analyzed in terms of signal intensity, homogeneity and patterns of contrast enhancement. The MR imaging findings and histopathology were correlated. Using 1.0-T and 1.5-T MR machines, axial T1 and T2 images and gadolinium-enhanced axial and sagittal T1 images were obtained. RESULTS: In all cases, iso-signal intensity to muscle was observed on T1-weighted images, and high signal intensity on T2-weighted images. After intravenous injection of gadolinium-DTPA in seven cases, intense contrast enhancement was seen in all lesions, which were homogenous on T1, T2, and enhanced MR images. Moderate cellularity of fibrous tissue, with even distribution of osteoid and an absence of secondary changes such as hemorrhage or cystic change were revealed by pathologic examination. CONCLUSION: Ossifying fibroma shows strong enhancement and homogenous signal intensity on MR images.The homogeneity of the MR signal depends on the even distribution of osteoid and an absence of secondary changes such as hemorrhage or cystic change.