应用膝关节三种磁共振加权像推断年龄

Age Estimation from Different Weighted Magnetic-resonance Images of Knee Joint

目的探索膝关节磁共振在年龄推断中的应用价值。方法收集10~25岁同时拍摄T1(T1WI)、T2(T2WI)和质子(PDWI)加权像的样本400例。对膝关节骨骺发育分级赋分,计算年龄相关性,建立多个年龄推断逐步线性回归模型;并绘制18岁推断的受试者工作特征曲线(receiver operating characteristic curve,ROC曲线),建立18岁年龄节点判别支持向量分类模型。结果不同加权像与年龄的相关性、ROC曲线下面积从高到低依次为T1WI、PDWI、T2WI。男性应用T1WI腓骨近端和PDWI股骨远端骨骺发育等级建立的模型准确性最高,平均绝对误差1.703岁。女性应用PDWI股骨远端和腓骨近端骨骺发育等级建立的模型准确性最高,平均绝对误差2.012岁。支持向量分类模型判别18岁年龄节点的准确性分别为男性0.840,女性0.920。结论膝关节T1WI、PDWI和T2WI均适用于年龄推断和18岁年龄节点判断。

Objective To compare the availability of weighted magnetic-resonance images(T1WI,T2WI and PDWI)of knee joint for the relevant individual’s age estimation of forensic purpose.Methods 50 subjects(each 25 of both the male and female)were randomly selected from 400 knee-aching individuals who aged between 10~25 years old with their knee-joint MRI images being simultaneously weighted into T1WI,T2WI and PDWI,therefore the ossifi cation status of each relevant knee was scored.Consequently,the relationship was analyzed between the ossifi cation stage and age so that multiple stepwise linear regressive models were set up for age estimation.With 18 years old taken as the threshold,the diagnostic accuracy was examined through the established receiver operating characteristic(ROC)curve and supportive vector classifi cation(SVC)model.Results The relevance was indeed observed between the discrepant weighted images and age/AUC(area under the curve)of ROC,demonstrating higher of both the correlation coeffi cient and AUC from the T1WI while lowest from the T2WI.The model established on the ossifi cation status of either T1WI of proximal fi bula or PDWI of distal femur was shown of the highest accuracy for male age estimation,with the mean absolute error being as 1.703 years.The model established on the ossifi cation status of PDWI of both the distal femur and proximal fi bula was of highest accuracy for female age estimation,with the mean absolute error being 2.012 years.The accuracy of SVC model diagnosing with 18 year-old threshold was 0.840 for male and 0.920 for female.Conclusion The images of T1WI,T2WI and PDWI of human knee joint among certain ages were applicable for age estimation and diagnosis under the 18 year-old threshold at present.