Objective To explore the repeatability and consistency of MR intravoxel incoherent motion (IVIM) parameters of rectal cancers.Methods Routine high resolution rectal MR and IVIM sequence were performed on 128 patients with pathologically proved rectal cancers before treatment.IVIM maps were generated from two sets of b-values (group A:0,5,10,20,30,40,60,80,100,150,200,400,600 and 1000 s/mm2;group B:0,5,10,20,30,40,60,80,100,150,200,400,600,1000,1500 and 2000 s/mm2),and IVIM parameters (D,D* and f) were measured.Then IVIM parameters were measured again by the same observer three months later.The intra-class correlation coefficient (ICC) and Bland-Altman graph analysis were performed to explore the repeatability and consistency of IVIM parameters.Results The differences of IVIM parameters (D,D* and f) derived from the two sets of b-values were statistically different (all P＜0.001).ICC and 95％ confidence interval (CI) of D,D* and f was 0.968 (0.955,0.977),0.780 (0.688,0.845) and 0.957 (0.934,0.970),respectively.Bland-Altman analysis showed that the 95 ％ limits of agreement of D,D* and f was (10.8％,22.4％),(14.8％,61.9％) and (-45.3％,-10.2％),respectively.There was significant difference of D* between twice measurement by the same observer (P=0.001);ICC and 95％CI of D,D* and f was 0.826(0.670,0.908),0.678 (0.392,0.830) and 0.910 (0.830,0.952),respectively.Furthermore,Bland-Altman analysis showed that the 95％ limits of agreement of D,D* and f were (-15.3％,12.4％),(-39.6％,61.2％) and (-22.6％,22.9％),respectively.Conclusion Under the two different sets of b-values,all IVIM parameters of rectal cancers demonstrate good consistency.In addition,D and f value show good repeatability.%目的 探讨直肠癌体素内不相干运动(IVIM) MRI参数测量的一致性和可重复性.方法 对128例经病理证实的直肠腺癌患者于治疗前行直肠常规高分辨MR和IVIM扫描.选择两种b值组合(A组:0、5、10、20、30、40、60、80、100、150、200、400、600和1000 s/mm2;B组:0、5、10、20、30、40、60、80、100、150、200、400、600、1 000、1 500和2000 s/mm2),拟合计算出两组IVIM参数图,分别测量肿瘤区域单纯扩散系数(D)、假性扩散系数(D*)和灌注分数(f)值.由同一观察者间隔3个月重复测量肿瘤区域D、D*和f值;采用组内相关系数(ICC)和Bland-Altman图评价测量的一致性和可重复性.结果 两种b值组合图像所测量D、D*、f值差异均有统计学意义(P均＜0.001);D、D*及f值的ICC及95％置信区间分别为0.968(0.955,0.977)、0.780(0.688,0.845)和0.957(0.934,0.970);Bland-Altman图显示差异百分比的±1.96标准差分别为(10.8％,22.4％)、(14.8％,61.9％)、(-45.3％,-10.2％).同一观察者2次测量D*值差异有统计学意义(P=0.001);D、D*及f值的ICC及95％置信区间分别为0.826(0.670,0.908)、0.678(0.392,0.830)和0.910(0.830,0.952);Bland-Altman图显示差异百分比的±1.96标准差分别为(-15.3％,12.4％)、(-39.6％,61.2％)、(-22.6％,22.9％).结论 两种b值组合图像测量直肠癌各IVIM参数的一致性良好,D值和f值测量的可重复性良好.
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