高分辨率MRI与IVIM-DWI对直肠腺瘤癌变的诊断价值

目的探讨高分辨率MRI及体素内不相干运动(IVIM)对直肠腺瘤癌变的诊断价值。方法回顾性分析山东省千佛山医院2017年1月至2018年9月收治的经术后病理证实的17例直肠腺瘤和18例直肠腺瘤癌变患者直肠腔内注入对比剂后的MRI图像,包括高分辨率T2WI序列及IVIM序列。以病理为金标准,计算高分辨率MRI诊断腺瘤癌变的准确率、敏感度、特异度、阳性预测值、阴性预测值,并比较高分辨率MRI与病理诊断腺瘤癌变的一致性。应用后处理软件分别测量腺瘤组和癌变组扩散相对受限的基底部以及边缘区的表观扩散系数(ADC)、真实扩散系数(D)、假性扩散系数(D^*)、灌注分数(f)值,用独立样本t检验比较腺瘤组、癌变组组内及组间基底部、边缘区的参数值差异,绘制受试者工作特征(ROC)曲线,计算曲线下面积(AUC)并分析诊断效能。结果高分辨率MRI诊断腺瘤癌变的敏感度、特异度、准确率、阳性预测值、阴性预测值分别为83.3%、82.4%、82.9%、83.3%、82.4%,高分辨率MRI诊断腺瘤癌变与病理诊断一致性较好(Kappa=0.657,P=0.000)。IVIM的研究中,癌变组扩散受限的基底部ADC、D、D^*、f值均低于边缘区,ADC、D、f值的差异有统计学意义(P<0.05),ADC、D、f值的AUC分别为0.698、0.776、0.736,最佳诊断阈值分别为0.544×10^-3mm^2/s、0.680×10^-3mm^2/s、0.218×10^-3mm^2/s,以此阈值诊断腺瘤癌变的特异度分别为94.4%、66.7%、88.9%,敏感度分别为38.9%、84.3%、50.0%;腺瘤组基底部与癌变组基底部间ADC D值的差异具有统计学意义(P<0.05),AUC分别为0.716、0.807,以0.875×10^-3mm^2/s、0.675×10^-3mm^2/s作为诊断阈值时,敏感度为94.4%、83.3%,特异度为47.1%、70.6%。结论高分辨率MRI T2WI序列可以较好地显示直肠腺瘤癌变的形态学变化,IVIM-DWI参数对诊断腺瘤癌变具有提示意义,可以辅助诊断腺瘤癌变。

The Value of High Resolution Magnetic Resonance Imaging and Intravoxel Incoherent Motion DWI in the Diagnosis of Rectal Adenoma with Malignant transformation

Objective To investigate the value of high resolution magnetic resonance imaging and intravoxel incorent motion Diffusion-weighted imaging in the diagnosis of rectal adenoma with malignant transformation.Methods Analysis of 35 patients(including 17 cases of rectal adenoma and 18 cases of rectal adenoma canceration)who were admitted to Shandong Qianshan Hospital from January 2017 to September 2018 after pathological confirmation of postoperative pathology.MRI images,including high-resolution T2WI sequences and IVIM sequences were performed.Using pathology as the gold standard,the accuracy,sensitivity,specificity,positive predictive value and negative predictive value of high-resolution MRI diagnosis of adenoma malignant transformation were calculated,and the consistency of high-resolution MRI and pathological diagnosis of adenoma malignant transformation was compared.The post-processing software was used to measure the apparent diffusion coefficient(ADC),true diffusion coefficient(D),pseudo-diffusion coefficient(D^*),and perfusion fraction(f)Value,the independent sample t test was used to compare the parameter value differences between the non-cancerous group,the cancerous group,and between the base and the marginal area,and ROC curve was drawn.Area under the curve was calculated to analyze the diagnostic efficacy.Results The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of high resolution MRI was 83%、82%、83%、83%、82%,respectively.HR-MRI had good consistency in the diagnosis of adenoma malignant transformation with pathological diagnosis(Kappa=0.657,P=0.000).Of the malignant transformation group,the ADC,D,D^*and f values of basal part were all less than those of the marginal part.And the difference of ADC、D、f values had statistic significance(P<0.05),area under the curve of ADC,D and f values were 0.698,0.776 and 0.736,the optimal diagnostic threshold was 0.544×10^-3mm^2/s、0.680×10^-3mm^2/s、0.218×10^-3mm^2/s,the specificity of this threshold to the diagnosis of adenoma malignant transformation was 94.4%、66.7%、88.9%,the sensitivity was 38.9%、84.3%、50%,respectively.On comparing the basal part between adenoma group and adenoma malignant transformation group,ADC and D value had statistic significance(P<0.05),area under the curve were 0.716、0.807,when the cutoff value was 0.875×10^-3mm^2/s,0.675×10^-3mm^2/s,the sensitivity was 94.4%、83.3%,the specificity was 47.1%,70.6%.Conclusion High-resolution MRI T2WI sequence can clearly show the morphological change of rectal adenoma malignant transformation.IVIM-DWI parameters have significance and can greatly aid in the diagnosis of adenoma malignant transformation.