对比增强 CT 的环形指数有助于鉴别乏脂性血管平滑肌脂肪瘤与肾细胞癌：组织学证实的 257 例小于 4 cm 的小肾癌的回顾性分析。
Circularity Index on Contrast-Enhanced Computed Tomography Helps Distinguish Fat-Poor Angiomyolipoma from Renal Cell Carcinoma: Retrospective Analyses of Histologically Proven 257 Small Renal Tumors Less Than 4 cm.
机构信息
Department of Radiology, Chungnam National University Hospital, Daejeon, Korea.
Department of Radiology, Chungnam National University College of Medicine, Daejeon, Korea.
出版信息
Korean J Radiol. 2021 May;22(5):735-741. doi: 10.3348/kjr.2020.0865. Epub 2021 Feb 9.
OBJECTIVE
To evaluate circularity as a quantitative shape factor of small renal tumor on computed tomography (CT) in differentiating fat-poor angiomyolipoma (AML) from renal cell carcinoma (RCC).
MATERIALS AND METHODS
In 257 consecutive patients, 257 pathologically confirmed renal tumors (either AML or RCC less than 4 cm), which did not include visible fat on unenhanced CT, were retrospectively evaluated. A radiologist drew the tumor margin to measure the perimeter and area in all the contrast-enhanced axial CT images. In each image, a quantitative shape factor, circularity, was calculated using the following equation: 4 × π × (area ÷ perimeter²). The median circularity (circularity index) was adopted as a representative value in each tumor. The circularity index was compared between fat-poor AML and RCC, and the receiver operating characteristic (ROC) curve analysis was performed. Univariable and multivariable binary logistic regression analysis was performed to determine the independent predictor of fat-poor AML.
RESULTS
Of the 257 tumors, 26 were AMLs and 231 were RCCs (184 clear cell RCCs, 25 papillary RCCs, and 22 chromophobe RCCs). The mean circularity index of AML was significantly lower than that of RCC (0.86 ± 0.04 vs. 0.93 ± 0.02, < 0.001). The mean circularity index was not different between the subtypes of RCCs (0.93 ± 0.02, 0.92 ± 0.02, and 0.92 ± 0.02 for clear cell, papillary, and chromophobe RCCs, respectively, = 0.210). The area under the ROC curve of circularity index was 0.924 for differentiating fat-poor AML from RCC. The sensitivity and specificity were 88.5% and 90.9%, respectively (cut-off, 0.90). Lower circularity index (≤ 0.9) was an independent predictor (odds ratio, 41.0; < 0.001) for predicting fat-poor AML on multivariable logistic regression analysis.
CONCLUSION
Circularity is a useful quantitative shape factor of small renal tumor for differentiating fat-poor AML from RCC.
目的
评估圆形度作为 CT 上小肾肿瘤的定量形状因子，以区分乏脂性血管平滑肌脂肪瘤（AML）与肾细胞癌（RCC）。
材料与方法
在 257 例连续患者中，回顾性评估了 257 例经病理证实的肾肿瘤（AML 或小于 4 cm 的 RCC），这些肿瘤在平扫 CT 上均未见可见脂肪。一位放射科医生在所有增强轴位 CT 图像上勾画肿瘤边界以测量周长和面积。在每张图像中，使用以下公式计算定量形状因子圆形度：4×π×（面积÷周长²）。采用每个肿瘤的中位数圆形度（圆形度指数）作为代表值。比较乏脂性 AML 和 RCC 之间的圆形度指数，并进行受试者工作特征（ROC）曲线分析。进行单变量和多变量二元逻辑回归分析，以确定乏脂性 AML 的独立预测因子。
结果
257 个肿瘤中，26 个为 AML，231 个为 RCC（184 个透明细胞 RCC、25 个乳头状 RCC 和 22 个嫌色细胞 RCC）。AML 的平均圆形度指数明显低于 RCC（0.86±0.04 与 0.93±0.02，<0.001）。RCC 各亚型的平均圆形度指数无差异（0.93±0.02、0.92±0.02 和 0.92±0.02，分别用于透明细胞、乳头状和嫌色细胞 RCC，=0.210）。圆形度指数的 ROC 曲线下面积为 0.924，用于区分乏脂性 AML 和 RCC。灵敏度和特异性分别为 88.5%和 90.9%（截断值，0.90）。较低的圆形度指数（≤0.9）是多变量逻辑回归分析中预测乏脂性 AML 的独立预测因子（优势比，41.0；<0.001）。
结论
圆形度是区分小肾肿瘤乏脂性 AML 与 RCC 的有用定量形状因子。
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