MR扩散加权成像单指数模型及体素内不相干运动模型参数直方图对上皮性卵巢癌分型的价值

Preliminary study of histogram analysis of mono-exponential and intravoxel incoherent motion models in epithelial ovarian cancer

目的：探讨单指数模型及体素内不相干运动（IVIM）模型各参数直方图对上皮性卵巢癌分型的价值。方法回顾性分析经手术病理证实为上皮性卵巢癌，且术前行盆腔MRI检查的40例患者。根据上皮性卵巢癌二元分型理论将其分为Ⅰ型（低级别，16例）和Ⅱ型（高级别，24例）两组。患者术前均行常规盆腔MRI平扫、多b值DWI和动态增强扫描，用后处理软件生成ADC、真扩散系数（D）、假扩散系数（D＊）和灌注分数（f）参数图及相应直方图。在每个直方图上测量记录平均值（Mean）、第10百分位数（10th）、最左侧10%区段平均值（MeanL）、第90百分位数（90th）、最右侧10%区段平均值（MeanR）。采用独立样本t检验（正态分布）和Mann-Whitney U检验（非正态分布）比较Ⅰ型和Ⅱ型患者的直方图参数值；对于两组间差异有统计学意义的参数值，应用ROC曲线分析它们鉴别两型卵巢癌的诊断效能。结果Ⅱ型上皮性卵巢癌组ADC、D、f的Mean、10th、MeanL、90th、MeanR均低于Ⅰ型组，差异均有统计学意义（P均〈0.05）；D＊的所有直方图参数差异均无统计学意义（P均〉0.05）。ADC值直方图Mean、10th、MeanL、90th、MeanR的ROC下面积分别为0.893、0.846、0.858、0.839和0.814；D值上述参数ROC下面积分别为0.898、0.880、0.878、0.895和0.872；f值上述参数ROC下面积分别为0.721、0.749、0.706、0.698和0.693。结论 DWI单指数模型及IVIM模型对评估卵巢癌的恶性程度具有价值，以ADC值和D值的诊断效能为佳。

Objective To evaluate the diagnostic performance of the histogram analysis of mono-exponential and intravoxel incoherent motion（IVIM） models to the dualistic model of epithelial ovarian cancer（EOC）. Methods Forty female patients with histopathologically proven epithelial ovarian cancer underwent preoperative MR examination. Scanning sequences included conventional imaging, diffusion-weighted magnetic resonance imaging with 11 b values （0, 30, 50, 100, 150, 200, 400, 600, 800, 1 000, 1 500 s/mm2） and dynamic contrast enhanced MRI （DCE-MRI）. Based on the dualistic model of EOC, all patients were divided into two groups：typeⅠ（low grade, n=16） and typeⅡ（high grade, n=24）. ADC, D, D＊and f maps and their corresponding histograms were generated by post-processing software. Based on an entire-tumour measurement, the following histogram parameters were recorded, respectively： （a） Mean; （b） the 10th percentile （10th）;（c） the mean of the top 10 percent （MeanL）;（d） the 90th percentile （90th）;（e） the mean of the bottom 10 percent （MeanR）. Two types were compared using independent sample t test or＆amp;nbsp;Mann-Whitney U test. And areas under ROC curve between two groups were assessed. Results For ADC , D, and f, all indices（Mean,10th,MeanL,90th,MeanR） of the histogram were significantly lower in typeⅡthan in type Ⅰ（P〈0.05）. All of parameters of D＊ had no significant different（P〉0.05）. D demonstrated a comparable accuracy with ADC in differentiating the grade of EOC （area under curve： Mean, 0.898 vs. 0.893; 10th, 0.880 vs. 0.846; MeanL, 0.878 vs. 0.858; 90th, 0.895 vs. 0.839; MeanR, 0.872 vs. 0.814）, and both ADC and D have better performance than f. Conclusion It is feasible to stratify the grade of EOC by mono-exponential and IVIM models with histogram metrics,diagnositic efficiency of ADC and D values are higher.