[Magnetic resonance in the study of aseptic necrosis of the femur head]

Avascular necrosis (AVN) of the femoral head is a common clinical problem due to the frequent use of corticosteroids and to the high incidence of hip fractures from osteoporosis and traumas. In order to demonstrate MR diagnostic capabilities, 31 patients (62 hips) were studied with MR imaging, CT, and conventional radiology. The patients had already been diagnosed as having AVN of the femoral head, or the condition was clinically suspected. MR staging of the disease was compared with CT staging and with plain radiographs. The authors suggest new MR staging method and adapt the radiographic classification developed by Ficat, Arlet, and Lecestre. The results of this comparative study demonstrate MR imaging to be most appropriate in the patients with equivocal/negative radiological/CT findings. On the contrary, MR imaging is unnecessary when AVN has already been diagnosed by means of other imaging modalities, because in these advanced cases MR diagnostic contribution either equals or is inferior to that of CT and conventional radiology.