Magnetic resonance imaging identifies early femoral head ischemic necrosis in patients receiving systemic glucocorticoid therapy.

Ischemic necrosis of bone, a frequent complication of glucocorticoid therapy, can result in disability due to bone collapse and destruction. Some investigators have suggested that core decompression of involved marrow benefits patients with early disease. As radiographs are normal in early disease, identification of patients has been dependent on nonspecific radionuclide imaging or more specific but invasive hemodynamic studies. In order to define a sensitive, noninvasive diagnostic tool, we compared magnetic resonance imaging (MRI) to 99mtechnetium diphosphonate and 99mtechnetium sulfur colloid scintigraphy in 10 consecutive glucocorticoid treated patients with suspected femoral head ischemic necrosis of bone but normal roentgenograms. MRI identified the ischemic necrosis (defined by characteristic radiographic progression or histology) in 13/13 femoral heads. Both scans together identified only 5/13 of the cases. Only 1/20 osteoarthritic femoral heads had MRI patterns similar to those seen in ischemic necrosis of bone. We conclude that MRI is a sensitive and relatively specific method to detect early femoral head ischemic necrosis of bone.