Diffusion MRI in ischemic epiphysis of the femoral head: an experimental study

To evaluate whether line-scan diffusion-weighted imaging (LSDWI) can provide temporal information of epiphyseal ischemia.

Ischemia was induced by ligation of arteries of the unilateral femoral head in piglets (N = 25). LSDWI was performed at several time points after ligation. A comparison of apparent diffusion coefficients (ADCs) was made between ischemic and control sides. The difference in percentage change of ADC in the ischemic hips between two neighboring time points was evaluated. A histological study was made after MR scanning.

Three hours after ligation, ADCs were significantly lower in the ischemic hips than in the contralateral (control) hips. At 72 hours after surgery, ADCs in the ischemic hips were significantly higher than in the control hips and continued to rise up until the sixth week after operation. Histological study revealed necrosis of chondrocytes and osteocytes and abnormal thickening of the epiphyseal cartilage in the ischemic femoral head.

The ADCs may be used as a marker of ischemia and necrosis in the femoral head; changes in the ADCs after the acute ischemia may reflect the evolution of ischemia and subsequent necrosis. LSDWI can be used for the evaluation of the duration and extent of ischemic injury in the epiphysis.