表观扩散系数直方图对肾透明细胞癌病理分级的诊断价值

目的探讨表观扩散系数(apparent diffusion coefficient,ADC)直方图对肾透明细胞癌(clear cell renal cell carcinoma,CCRCC)病理分级的诊断价值。方法对34例CCRCC患者的常规MRI及扩散加权成像(diffusion-weighted imaging,DWI)资料进行回顾性分析。依据病理结果,分为低级别组(19例)、高级别组(15例)。测量记录不同级别CCRCC的ADC直方图参数,包括ADC值的最大值、最小值、平均值、中位数、偏度值、峰度值。采用独立样本t检验或Mann-Whitney U检验比较不同级别CCRCC ADC直方图参数的差异。结果低级别组CCRCC的ADC直方图最小值、平均值、中位数均高于高级别组[(1.09±0.23)×10^-3 mm^2/s vs(0.81±0.09)×10^-3 mm^2/s、(1.86±0.27)×10^-3 mm^2/s vs(1.58±0.14)×10^-3 mm^2/s以及(1.85±0.23)×10^-3 mm^2/s vs(1.59±0.12)×10^-3 mm^2/s,P<0.05],且低级别组ADC直方图以负偏态分布为主;两组ADC直方图的最大值、峰值差异无统计学意义(P>0.05)。ADC值直方图的最小值鉴别低级别、高级别CCRCC的效能最高,曲线下面积(area under curve,AUC)为0.895,对应的最佳诊断阈值、Youden指数以及敏感度、特异度分别为0.898×10^-3 mm^2/s、0.761、86.67%、89.47%。结论表观扩散系数直方图有助于鉴别低级别、高级别CCRCC,ADC最小值诊断效能最优。

Diagnostic value of apparent diffusion coefficient histogram for pathological grading in clear cell renal cell carcinoma

Objective  To evaluate the diagnostic value of apparent diffusion coefficient（ADC） histogram for the classification of clear cell renal cell carcinoma（CCRCC）. Methods A retrospective analysis was performed on 34 patients with CCRCC by conventional MRI and diffusion-weighted imaging（DWI）. According to pathological findings，the patients with CCRCC were divided into low grade group（19 cases） and high grade group（15 cases）. The ADC histogram parameters of different grades of CCRCC were measured and recorded，including maximum，minimum，mean，median，skewness and kurtosis. Independent sample t test or Mann-Whitney U test were used to compare the difference of ADC parameters. Results The minimum，mean and median of ADC histogram of low grade CCRCC were higher than that of high grade CCRCC ［（1.09±0.23） ×10^-3  mm²/s vs （0.81±0.09）×10^-3 mm²/s 、（1.86±0.27）×10^-3 mm²/s  vs （1.58±0.14）×10^-3 mm²/s and （1.85±0.23）×10^-3 mm²/s  vs （1.59±0.12）×10^-3 mm²/s ，P＜0.05］. Moreover，the low grade CCRCC was dominated by negative skewness. There were no significant difference in the maximum and peak values between the two groups （P>0.05）. In the whole tumor ADC histogram，the diagnostic efficiency of the ADC minimum was the highest，the area under the curve （AUC） was 0.895，and the corresponding optimal diagnostic threshold index，Youden index，sensitivity and specificity were 0.898×10^-3 mm²/s，0.761，86.67% and 89.47%，respectively. Conclusions The ADC histogram helps to identify different grade of CCRCC，and the ADC minimum has the best diagnostic efficiency.