女性盆腔体素内不相干运动扩散加权成像分段拟合及完全拟合算法定量参数稳定性及一致性分析

Stability and consistency of quantitative parameters of female pelvic IVIM-DWI segmented fitting and full fitting algorithm

目的:比较分段拟合及完全拟合两种拟合算法测得正常女性盆腔体素内不相干运动扩散加权成像(IVIM-DWI)双指数模型相关参数的稳定性及一致性。方法:对符合入组标准的21例健康女性志愿者采集盆腔IVIM-DWI磁共振图像,利用后处理软件中2种不同拟合算法(阈值b=200 s/mm^(2))对图像进行定量分析,并分别获得IVIM双指数模型各参数值。采用配对t检验比较2种拟合算法获得的女性盆腔不同部位(子宫体肌、臀大肌及髂骨骨髓)各参数值组间差异,并利用变异系数(CV)评估2种拟合算法所获得各参数的稳定性。采用组内相关系数(ICC)和Bland-Altman图分析2名医师测量数据的一致性。结果:①医师A采用分段拟合及完全拟合测得的IVIM参数值显示同一部位两种拟合算法测得各参数值比较除子宫肌Dfast及髂骨f值无统计学差异外,其他参数值均具有统计学差异(P<0.05,双尾),其中分段拟合获得的Dfast测量值均低于完全拟合,Dslow、f测量值均高于完全拟合。除完全拟合算法臀大肌及髂骨Dfast测量值的CV值小于分段拟合外,分段拟合算法各参数的CV值均小于完全拟合,其中又以子宫体肌分段拟合测得Dslow的CV值最小;②观察者间一致性分析显示分段拟合算法测得的子宫肌的Dslow值和f值的ICC值均>0.75,其中又以Dslow的ICC值最高(0.90);Bland-Altman图显示观察者间测得数据以子宫体肌的分段拟合方法Dslow值差值分布较为集中。结论:分段拟合方法测得健康女性盆腔双指数IVIM各参数值的整体稳定性较完全拟合好,但是除分段拟合测得子宫体肌的Dslow、f值外,两种拟合方法测得各参数值的一致性欠佳。

Objective:To compare the stability and consistency of segmented fitting and full fitting algorithms based bi-exponential intravoxel incoherent motion(IVIM)diffusion MRI in female pelvis.Methods:21 healthy female volunteers who met the enrollment criteria were recruited,and the images were quantitatively analyzed using segmented fitting and full fitting algorithms in the post-processing software(threshold b=200s/mm 2).Two radiologists performed data measurements independently on the myometrium,gluteus maximus and iliac bone marrow.The paired t test was used to compare the differences between the parameter values of different parts of the female pelvis obtained by the two fitting algorithms,and the coefficient of variation(CV)was used to evaluate the stability of the parameters.The consistency of inter-group data was conducted by the intra-class correlation coefficient(ICC)and Bland-Altman plot.Results:①The IVIM parameter values measured by physician A using the segmented fitting and full fitting on the myometrium,gluteus maximus,and ilium showed the values of Dfast obtained by the segmental fitting were lower than the full fitting,while the values of Dslow and f were higher than the full fitting,and the results were statistically different except for the values of Dfast of the myometrium and f of the ilium(P<0.05,two tails).The CV values of the parameters of segmental fitting algorithm were all smaller than that of full fitting except that the CV values of the Dfast of the gluteal muscles and iliac bones of the full fitting algorithm were smaller than that of the segmental fitting.②The inter-observer agreement analysis showed that ICC values of Dslow and f of the myometrium measured by the segmented fitting algorithm were both higher than 0.75,and the ICC value of Dslow was the highest(0.90).The Bland-Altman diagram showed that the difference of Dsolw values of the myometrium performed by the segmental fitting algorithm between the observers was more concentrated.Conclusion:For healthy female pelvis,the overall stability of IVIM bi-exponential parameters measured by the segmented fitting algorithm was better than the full fitting.However,except for the Dslow and f values of the myometrium performed by the segmental fitting,the consistency of the parameters measured by the two fitting algorithms was poor.