Abstract：Objective: To evaluate the change of perfusion in super-early ischemia of growth cartilage of femoral head induced by hyperabduction and its characterization of blood perfusion. Materials and Methods: Thirty-two femoral heads of 16 two-week-old piglets were studied. At the beginning all piglets were placed with hips in neutral position and MR scans were performed. After MR exams, all piglets were placed with bilateral hips in consistent hyperabduction for 30 minutes and the same MR exams were repeated. After that, all piglets were allowed to ambulate. After 24 hours the same MRI was performed again. The main MR sequences included perfusion MR imaging and conventional Gd-enhanced SE T1WI. Enhancement ratios of the various anatomic regions of femoral heads in hips with hyperabduction were compared with those in hips with neutral position. The corresponding histologic findings were evaluated. Results: The enhancement ratios of physes and Spongiosas of femoral heads with hips in hyperabduction were significantly less than those in normal physes and Spongiosas(P<0.05). Physes and spongiosas with hyperabduction enhanced significantly slower than those with neutral position(P<0.05). The MRI appearances of growth cartilage after ambulation were the same as those before abduction. Histologic findings showed no evidence of osteonecrosis or necrosis of chondrocyte. The transphyseal vessels in these piglets with hyperabduction were confirmed histologically. Conclusions: Perfusion MRI can detect super-early ischemia of growth cartilage of femoral head induced by hips with hyperabduction.
2007, Vol. 18 
