Diffusion‐weighted MR study of femoral head avascular necrosis in severe acute respiratory syndrome patients

Abstract

To evaluate the apparent diffusion coefficient (ADC) of femoral head avascular necrosis (AVN) in severe acute respiratory syndrome (SARS). Seventy‐nine SARS patients with hip pain underwent both conventional and diffusion‐weighted MRI (b‐value = 0–1000 seconds/mm²). The abnormal regions on the diffusion‐weighted images were outlined by using the conventional images as guides, and the ADCs were calculated. The ADC differences between normal and AVN femoral heads were compared. Of the 158 hips examined, 28 had AVN (11 with bilateral hip AVN, three with right hip AVN, and three with left hip AVN). The mean ADC was markedly greater in the AVN femoral head (1.66 × 10^–3 mm²/second ± 0.20) than in the normal femoral head (0.47 × 10^–3 mm²/second ± 0.082; P < 0.0001). There was no overlap between the normal and AVN femoral heads. DWI can provide valuable information regarding the diffusion properties of femoral head AVN, and markedly increased diffusion was identified in AVN. J. Magn. Reson. Imaging 2005.