Application of CT and MRI in volumetric measurement of necrotic lesion in patient with avascular necrosis of the femoral head / 中华放射学杂志

ABSTRACT

Objective To investigate the feasibility and accuracy of volumetric measurement of necrotic lesion using CT and MRI,and to assess the value of necrotic lesion volume in predicting collapse of the femoral head in patients with avascular necrosis of the femoral head(ANFH). Methods Comparison among CT,MRI and gross section was performed in 25 femoral heads of 18 patients who underwent total hip replacement for established ANFH.The volume of necrotic lesion was measured using fluid displacement.CT and MRI data were transferred to a computer to calculate the volume of necrotic lesion using software.One way ANOVA was used to compare the volumes of necrotic lesion measured by CT,MRI and gross section.A total of 62 patients (92 hips) who were diagnosed with ANFH but without collapse by CT were followed up 24 months.Student t-test was used to compare the ratio of the volumes of the necrotic lesion and entire femoral head in the hips with and without collapse and ROC curve analysis was carried out.Results CT and MRI coincided with gross section in the necrotic area,proliferative area and extralesional area.The volumes of the necrotic lesion measured by CT,MRI and gross section were ( 20.5 ± 5.2 ),( 21.4 ± 4.8 ),( 20.9 ± 5.2 ) cm3,respectively.There was no significant difference among the necrotic volumes measured by the three methods(F =0.185,P =0.831 ).In fifty-seven out of 92 hips,collapse of the femoral head occurred during the follow-up.The ratio of the volumes of the necrotic lesion and entire femoral head was higher in hips with collapse than in hips without collapse[ (34.5 ±9.3)％ vs.(23.4 ±8.4)％ ;t =5.749,P=0.000].The area under the ROC curve was 0.808. Conclusions The volume of the necrotic lesion plays an important role in the collapse of femoral head in patients with ANFH.Both CT and MRI can identify the shape and location of the necrotic lesion intuitively and stereospecifically and can determine the volume of the necrotic lesion accurately.