Midterm follow-up of SARS patients treated with corticosteroid with MR imaging

Abstract

Objective To observe the MRI differences between normal adult femoral head and os- teonecrosis of the femoral head in severe acute respiratory syndrome (SARS) patients treated with corticos- teroid. Methods From Jun. 2003 to Jan. 2004, 539 SARS patients (1078 hips) treated with corticosteroid were examined by radiography and MRI. 130 cases (210 hips) developed osteonecrosis of the femoral head (ONFH), 459 cases (868 hips) without ONFH. Patients with ONFH were followed up by MRI annually. From February to November in 2007, 510 SARS patients (1020 hips) were examined by radiographs and MRI a-gain. All MRI examinations were performed with same protocol. The images of femoral head with or without necrosis were compared. Results No ONFH was found at the second examination. Necrotic lesions were detected on MRI in 6 months since the administration of corticosteroid. The signal types of ONFH changed after collapse or operation. Low signal intensity on T1 weighted image and high signal intensity on corre-spending short time inversion recovery image (STIR) was still observed in all necrotic femoral head. Three necrotic femoral heads showed lesion size reduction on MRI. Four types of MRI were observed in normal femoral head. 24 hips with abnormal signal on T1 weighted image and normal signal on the corresponding STIR were diagnosed as normal. Conclusion Necrotic lesions can be detected on MRI within 6 months since the administration of corticosteroid. there is signal variability in normal femoral head. Band form with low signal intensity on T1 weighted image and high signal intensity on corresponding STIR can be used as di- agnostic standards of ONFH. Only little necrotic femoral heads showed lesion size reduction on MRI. Key words: Magnetic resonance imaging; Femur head necrosis; Severe acute respiratory syndrome