健康成人肾脏磁共振体素内不相干运动及扩散张量成像的参数分析

Intravoxel incoherent motion diffusion-weighted imaging and diffusion tensor imaging of normal kidney

目的分析磁共振体素内不相干运动成像(IVIM-DWI)及扩散张量成像(DTI)中成人正常双肾的各参数指标的特点,并评估各参数的可靠性。方法选择35位健康成人志愿者行肾脏IVIM-DWI及DTI扫描并将图像进行后处理,由2名影像科医师测量双肾上、下极及中部的皮、髓质IVIM-DWI参数D、D*、f值及DTI参数FA值,比较双侧肾脏,同侧肾不同部位及同部位的皮髓质之间各参数平均值的差异。结果 IVIM-DWI及DTI各参数在双侧肾脏间无统计学差异(P>0.05);同侧肾脏在不同部位各参数测量值间亦无统计学差异(P>0.05)。同部位肾脏D值在皮质高于髓质(t=3.215,P<0.05),FA值在髓质高于皮质(t=-6.088,P<0.05)而皮髓质的D*、f值差异无统计学意义(P>0.05)。两次所测得的FA及D值组内相关系数分(ICC)具有较高可信度,D*及D值可信度一般。结论 FA及D值在肾皮、髓质中具有显著差异,且具有较高的可重复性,可作为反映肾功能的稳定指标;而D*及f值可重复性一般,尚需扩大样本进一步研究期应用价值。

Objective To assess the characteristic of diffusion tensor imaging （DTI） and intravoxel incoherent motion （IVIM）-DWI parameters in healthy kidneys.Methods 35 healthy adult volunteers underwent DTI and IVIM-DWI examination of kidneys.Two radiologists determined the pure diffusion coefficient （D）,pseudo diffusion coefficient （D＊）,perfusion fraction （f） in the upper,middle and lower portions of the bilateral renal cortex and medulla.Intraclass correlation coefficient test was used to verify repeatability.The differences of upper,middle,and lower kidneys were compared using ANOVA analysis.The differences between left and right kidneys,between the cortex and medulla were compared with matched pairs test.Results There were no statistically significant differences of all parameters between DTI and IVIM-DWI for bilateral kidneys,upper,middle and lower portions of solitary kidneys.Fractional anisotropy （FA） values in the medulla were significantly higher than that in the cortex （t=-6.088,P〈0.05） whereas D values of the cortex were significantly higher than those of the medulla （t=3.215,P〈0.05）.There was no significant difference between the D＊ andfvalues of cortex and medulla （P〉0.05）.FA and D measurements were more consistent than that of D＊ andf.Conclusion FA and D differ significantly between renal cortex and medulla and have higher consistency in measurement than D＊ andffor accurate renal function assessment.