MR diffusion imaging in diagnosis of femoral head necrosis

Objective To assess the value of MR DWI in diagnosis and staging of femoral head necrosis.Methods Thirty-four patients with femoral head necrosis(40 hip joints) and 90 healthy volunteers(180 hip joints) were included.The patients were divided into 3 groups according to Steinberg stage(Ⅰ—Ⅱ of group 1,Ⅲ—Ⅳ of group 2,Ⅴ—Ⅵ of group 3).SE-EPI-DWI was performed to obtain images with b values of 300,500 and 700 s/mm2,respectively.ADC maps were obtained with Functool software.ADC values of femoral head were measured using 100 mm2 ROIs,and then were statistically analyzed.Results With b value of 300,500 and 700 s/mm2,the mean ADC value of femoral head necrosis was(13.00±2.54)×10-4 mm2/s,(10.73±3.10)×10-4 mm2/s and(8.77±1.55)×10-4 mm2/s,respectively,while the mean ADC value of healthy femoral heads was(3.63±1.34)×10-4 mm2/s,(1.87±0.76)×10-4 mm2/s,(1.49±0.53)×10-4 mm2/s.There were significant statistical differences in ADC values of normal femoral head and femoral head necrosis(all P0.05).ADC values of femoral head necrosis in group 1 were minimum,and were maximum in group 2,then reduced in group 3(P0.05).Conclusion DWI can display the femoral head necrosis clearly.ADC values contribute to distinguishing the normal and pathological regions of femoral head,as well as staging necrosis of the femoral head.