The Correlation Between The MRI Characteristics And Appearance On Digital Subtraction Angiography For Bone Marrow Edema In Osteonecrosis Of The Femoral Head

ObjectiveTo observe the correlation between the MRI characteristics and medullary cavity congestion on digital subtraction angiography(DSA)for bone marrow edema(BME)in osteonecrosis of the femoral head(ONFH)and to discover the pathogenesis of bone marrow edema in patients of ONFH.MethodFrom January 2002 to December 2007,54 hips with osteonecrosis in 31 enrolled patients treated by interventional therapy were reviewed.This study include 19 men and 12 women with history from 2 month to four years,ranging in age from 18-65 years.All the patients were examined with X-ray and MRI before interventional therapy.MRI characteristics were analyzed using SE T1WI,T2WI and STIR scaning,both coronal and axid were performed in all patients. BME was identified from MRI with grade 0 to grade 3.Based on rating scale of pain, ONFH were divided into no pain(grade 0),mild pain(grade 1)and moderate or severe pain (grade2).According to ARCO staging system,ONFH were divided intoⅠ-Ⅳstages. Statistical methods was analysed by SPSS13.0 statistics package.The rate comparison was used by X~2(chi-square)test;the average comparison was used by T-test or analysis of variance,or using a rank test when variance missing, and correlation analysis was used by correlation and regression analysis. Level test was designated asα=0.05.Results 36 of 38 hips with marrow edema around focal osteonecrosis on initial MRI showed congestion on DSA,2 showed no congestion,whereas only 3 of 16 hips without BME showed congestion,13 showed no congestion.There were 38 medulla edema focuses in the 31 patients.T1WI detected 35(92.1%)and T2WI detected 33(86.8%),and all of the focuses were shown on the STIR series(100%).BME was defined as an ill-defined area of low signal intensity on T1WI images with corresponding high signal intensity on T2WI images that involved the femoral head and neck beyond the necrotic zone and extending to intertrochanteric regions.Pain grading correlated with BME rating(P＜0.001).With the advance of disease,the positive rate of BME rating increased gradually(from stageⅠ-Ⅳwere 50%,72.8%,75%,33.3%respectively).ConclusionsThe bone marrow edema around focal osteonecrosis on magnetic resonance images is strongly associated with medullary cavity congestion on DSA and associated with the grading of ONFH,the form of bone marrow edema may associated with stasis of the microcirculation.BME was the most significant risk factor for worsening of hip pain.MRI in BME could improve the diagnosis value and clinical significance,especially on STIR series.Abatement of BME and relief of pain symptom after interventional therapy demonstrate the improvement of microcirculation,which is profit to postpone the progression disease.