Magnetic resonance imaging in diagnosis of transient osteoporosis of the hip.

The results of magnetic resonance (MR) imaging in six patients with transient osteoporosis of the hip were reviewed. Short TR/TE (repetition time/echo time) images demonstrated diffusely decreased signal intensity in the femoral head and intracapsular region of the femoral neck. Increased signal intensity was noted with progressive T2 weighting. Bone biopsies were performed in four patients. Histologic findings were nonspecific and included fat necrosis, marrow edema, increased bone resorption, and reactive bone formation. Repeat MR scans in two patients, performed six and eight months after the initial scans, showed an almost complete return to normal marrow signal. All patients became asymptomatic without bony deformity. In the appropriate clinical setting, MR scanning can aid in the diagnosis of transient osteoporosis as the cause of a painful hip.