非高斯扩散加权成像:拉伸指数模型与分数阶微积分模型对术前预测肝细胞癌微血管侵犯的价值

Non-Gaussian Diffusion-Weighted Imaging:the Value of Stretch Index Modeland Fractional Calculus Model in Predicting Microvascular Invasion of Hepatocellular Carcinoma before Operation

目的评估拉伸指数模型(SEM)与分数阶微积分(FROC)扩散模型在术前预测肝细胞癌(HCC)微血管侵犯(MVI)中的潜在价值。方法前瞻性搜集术前2周内行3.0 T MRI多个b值(0~3000 s/mm^(2))的扩散加权成像(DWI)扫描,术后病理证实为HCC的患者76例,分别采用单指数模型、SEM和FROC进行数据拟合,获得对应参数:表观扩散系数(ADC);分布扩散系数(DDC)和扩散异质性系数(α);扩散系数(D)、空间分数阶参数(β)和空间参数(μ)。采用组内相关系数(ICC)以评估两位放射科医师量化参数的一致性。采用独立样本t检验比较MVI阳性组和MVI阴性组之间各个扩散参数的差异。P<0.05表示差异具有统计意义。通过受试者工作特性(ROC)曲线评价两组之间有显著差异的参数的诊断效能。结果76例HCC患者中,包括MVI阳性40例及MVI阴性36例。HCC MVI阳性组的DDC值与D值均显著低于MVI阴性组,差异有统计学意义(P均<0.001);HCC MVI阳性组的α值均显著高于MVI阴性组,差异有统计学意义(P<0.005);DDC、D及α值的ROC曲线下面积(AUC)分别为0.876、0.824和0.722,最佳诊断界值分别为1.477μm^(2)/ms、0.958μm^(2)/ms、0.550。ADC、β和μ在两组的差异无统计学意义。结论SEM与FROC的影像学定量参数,对术前无创性评估HCC患者是否存在MVI具有潜在价值。

Objective To evaluate the potential value of stretching index(SEM)and fractional order calculus(FROC)diffusion models in preoperative prediction of microvascular invasion(MVI)in hepatocellular carcinoma(HCC).Methods A prospective collection of 76 patients who underwent diffusion-weighted imaging scans with multiple b values of 3.0 TMRI(0-3000 s/mm^(2))within 2 weeks before surgery and had postoperative pathologically confirmed hepatocellular carcinoma were fitted to the data using a single exponential model,a stretched exponential model and a fractional order calculus model to obtain the corresponding parameters:apparent diffusion coefficient ADC;distribution diffusion coefficient DDC and diffusion heterogeneity coefficientα;diffusion coefficient D,spatial fractional order parameterβand spatial parameterμ.The intra-group correlation coefficient ICC was used to assess the agreement of the quantitative parameters between the two radiologists.Independent samples t-test was used to compare the differences in each diffusion parameter between the MVI positive and MVI negative groups.P<0.05 indicates that the differences are statistically significant.The diagnostic efficacy of the parameters with significant differences between the two groups was evaluated by subject operating characteristic(ROC)curves.Results Among the 76 patients with hepatocellular carcinoma,therewere 40 MVI-positive and 36 MVI-negative cases.The DDC and D values in the MVI-positive group of hepatocellular carcinoma were significantly lower than those in the MVI-negative group,and the differences were statistically significant,with P values<0.001.Theαvalues in the MVI-positive group of hepatocellular carcinoma were significantly higher than those in the MVI-negative group,and the differences were statistically significant,with P values<0.005.The areas under the ROC curves for DDC,D andαvalues were 0.876,0.824 and 0.722,respectively.The optimal diagnostic cut-off values were 1.477μm^(2)/ms,0.958μm^(2)/ms,and 0.550,respectively.the differences in ADC,β,andμwere not statistically significant in the two groups.Conclusion Stretch index model with fractional order calculus model of quantitative imaging parameters is potentially valuable for preoperative noninvasive assessment of the presence of MVI in patients with hepatocellular carcinoma.