| ObjectiveDynamic Gd - DTPA enhanced MR imaging was performed in the model of steroid - induced ANFH to analyze marrow perfusion and in-vesigate the correspondent pathological changes in the femoral head of different stage, so as to further explore correlation between MR bone perfusion and pathology of steroid - induced ANFH and to provide primarily diagnostic evidence theriotically.Materials and methodsTwenty Japanese male adult white rabbits weighing 2. 5 -3.5 Kg were divided into experimental group and control group. The experimental group which contained 16 rabbits was subdivided into 4 groups (4 rabbits in each subgroup). They received intramuscular injection of 8.0 mg/Kg methylprednisolone twice a week and the treatment last 4 weeks, eight times mostly. The control group contained 4 rabbits who did not receive any treatment. The rabbits of two groups received intramuscular injection of penicillin 100,000 IU twice a day to prevent infection. Twenty rabbits were proved healthy by X - ray plain radiograph and MR imaging before steroid was treated. MR imaging including SE sequence T1WI, FSE sequence T2W1 and STIR sequence of coronary scan and Gd - DTPA perfusion dynamic enhanced scan was obtained by GE signa CV/i 1. 5T superconductive MR machine with head coil. Rabbits of experimental group were examined by MR insame method in the second week, forth week, sixth week and eighth week after treatment. MR imaging of right femoral head of every rabbits was post treated with Functool software package after scanning of perfusion. Time - signal intensity dynamic curve was depicted to analyze the marrow signal intensity changes of femoral head in different stage. After MR imaging, whether normal or abnormal sample were his-tological examined after killed then. HE stained and EM ultramicro-structure was analyzed. MRI and histological findings were studied cor-relatively.MRI: The marrow signal intensity of femoral head of 20 rabbits in T1WI and T2WI kept high before steroid was treated, but in STIR sequence, were inhibited and turned into modest, even low than that of peripheral fat tissue. No liquid was found in joint cavity. Signal did not apparently change after in second week after rabbits were treated. Low signal intensity of fine strip - like was detected in the high signal intensity of femoral head, of 2 ones among 4 rabbits in the forth week. Low signal intensity of fine strip - like was detected in the high signal intensity of femoral head of 4 rabbits in the sixth week. Long T2 signal of in intra - cavity was 100% detected in experimental group after rabbits were treated.MR perfusion: Marrow signal intensity of femoral head varied with time in STIR and Gd - DTPA sequence. Perfusion imaging showed early and fast enhancing in control group and present a falling tendency with time passing by the slope of time - signal intensity curve gradually declined in early stage of blood perfusion in the second, forth week, sixth week and eighth week in experimental group, and intensity of perfusion descented gradually. These difference between experimental one and control group was significant.PathologyAnatomy; There was no difference in anatomical morphology of femoral heads between experimental rabbits and control ones, however, femoral heads of experimental rabbits displayed osteoporoses and was easy to dissect in coronary section. Apparent congestion was observed in the section in the second, forth,sixth and eighth week.The pathological changes in light microscope and electron microscope were mainly in subchondral area . In the second week, there was no apparent change in light microscope section in experimental group. In the forth week, fatty tissue in the marrow of femoral head of 4 rabbits increased gradually . The nuclei of adipocyte disappear and disrupt partly and " the foam cell" were detected. In the sixth week, hemorrhage was seen in the marrow of femoral heads of 4 rabbits. Meantime, pyknosis margin aggregation and more deeply stained of the nuclei of part osteocyte in the trabecular w...
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