平扫CT密度及其直方图参数在少脂肪肾血管平滑肌脂肪瘤与肾嫌色细胞癌、乳头状肾细胞癌鉴别诊断中的作用

Ability of attenuation measurement and histogram analysis in differentiating minimal-fat renal angiomyolipoma from papillary and chromophobe renal cell carcinoma on unenhanced CT

目的:探讨平扫CT密度及其直方图参数对少脂肪肾血管平滑肌脂肪瘤(angiomyolipoma,AML)与肾嫌色细胞癌、乳头状肾细胞癌的鉴别诊断作用。方法:分析18例少脂肪肾AML、15例肾嫌色细胞癌、18例乳头状肾细胞癌的平扫CT图像,测量并计算平均密度及其直方图10%、25%、50%密度,以及10%/平均密度比值,比较以上参数在少脂肪肾AML与肾嫌色细胞癌、乳头状肾细胞癌之间的差异,选取差异有统计学意义的参数进行少脂肪AML与后两者的鉴别诊断,应用受试者工作特征(receiver operating characteristic,ROC)曲线评估各参数诊断效能的优劣。结果:少脂肪肾AML的平均密度及其直方图10%、25%和50%密度均显著高于肾嫌色细胞癌和乳头状肾细胞癌,但10%/平均密度比值无差异。以平均密度及其直方图10%、25%和50%密度鉴别少脂肪肾AML与肾嫌色细胞癌的ROC曲线的曲线下面积(area under curve,AUC)为0.80、0.76、0.78和0.82,各参数效能无明显差异;鉴别少脂肪肾AML与乳头状肾细胞癌的AUC为0.69、0.70、0.68和0.72,各参数效能差异无统计学意义。结论:平扫CT密度及其直方图参数有助于鉴别少脂肪肾AML与肾嫌色细胞癌、乳头状肾细胞癌,但诊断效能仍有待提高。

Objective： To investigate the ability of attenuation measurement and histogram analysis in differentiating minimal-fat renal angiomyolipoma（AML） from papillary and chromophobe renal cell carcinoma（RCC） on unenhanced CT. Methods： Unenhanced CT images of 18 minimal-fat AML, 15 chromophobe RCC and 22 papillary RCC were analyzed. The mean attenuation and relative histogram parameters（10^th, 25^th, 50%th values and 10 th/mean value） of the lesions were measured and calculated. The parameters were compared among AML, chromophobe RCC, and papillary RCC. The parameters with significant difference would be applied in differentiating of minimal-fat AML from two RCCs. The effeciency of the parameters for differentiation was assessed by receiver operating characteristic（ROC） curve. Results： The mean and 10^th, 25^th, 50^th values of the attenuation of minimal-fat AML were significantly higher than chromophobe and papillary RCCs, but no significant difference was found in 10 th/mean value. The values of area under ROC curve（AUC） of the parameters for differentiating AML from chromophobe RCC were 0.80, 0.76, 0.78, 0.82, respectively, and no significant difference was observed among them. The AUC values of the parameters for differentiating AML from papillary RCC were 0.69, 0.70, 0.68, 0.72, respectively, and no significant difference was observed among them. Conclusion： On unenhanced CT attenuation measurement and histogram analysis provide more parameters for distinguishing minimal-fat AML from papillary and chromophobe RCCs, but the efficiency should be further improved.