Fibrous dysplasia: magnetic resonance imaging appearance at 1.5 tesla.

Fibrous dysplasia has been described in a small number of cases in the literature as showing low signal intensity on T1- and T2-weighted magnetic resonance images. We reviewed magnetic resonance scans of 13 patients with fibrous dysplasia to determine if there might be a characteristic appearance. All lesions had sharply defined borders and were of intermediate signal intensity on T1-weighted images. With T2 weighting, six lesions (46%) showed high signal intensity, four (31%) showed persistent intermediate signal intensity, and three (23%) showed mixed intermediate and high signal intensity. Ten lesions (77%) had inhomogeneous signal intensity and three (23%) had homogeneous signal intensity. We concluded that fibrous dysplasia does not have a characteristic appearance on magnetic resonance imaging. However, magnetic resonance may be helpful in establishing the diagnosis of fibrous dysplasia if low to intermediate signal intensity is seen on both T1- and T2-weighted images. This situation occurred in 54% of our cases, whereas the other 46% had nonspecific signal characteristics indistinguishable from many other bone lesions.