多个小面积感兴趣区域测量法在CT平扫中鉴别肾细胞癌与肾囊肿的应用价值

The Value of Small Region-of-interest Measurements in Distinguishing Renal Cell Carcinoma and Renal Cysts on Unenhanced CT

目的探讨多个小面积感兴趣区域(ROI)的测量方法在CT平扫中鉴别肾细胞癌(RCC)与肾囊肿的价值.方法回顾性分析2013年5月-2018年5月经手术病理证实的98例RCC的CT平扫及增强图像,使用单个大面积(肿块面积的2/3)ROI测量98例RCC的平扫CT值,分析不同病理类型RCC平扫CT值的统计学差异.将密度均匀且平扫CT值≤20 HU的RCC采用多个(≥6)均匀分布的小面积(≤0.6 cm2)ROI进行重新测量,评估其最终CT值.结果采用单个大面积ROI测量法,98例RCC平扫CT值为(30.9±9.4)HU,56例肾透明细胞癌(CCRCC)平扫CT值为(28.3±8.6)HU,28例乳头状肾细胞癌(PRCC)平扫CT值为(34.2±10.1)HU,14例嫌色细胞癌(CRCC)平扫CT值为(35.1±9.2)HU,三组间平扫CT值差异无统计学意义(P=0.06).98例RCC中25例RCC的CT值≤20 HU,其中21例RCC密度不均匀,4例RCC密度均匀,将4例密度均匀RCC采用多个小面积ROI测量,其最大CT值>20 HU(范围25~32 HU),且均为CCRCC.结论采用单个大面积ROI测量时,密度均匀的RCC平扫CT值可≤20 HU,易误诊为肾囊肿,采用多个小面积ROI可提高RCC的诊断正确率.

Objective To evaluate the value of small region of interest (ROI) measurements in distinguishing renal cell carcinoma (RCC) and renal cysts on unenhanced CT. Methods A retrospective analysis was conducted on CT plain and enhanced images of 98 RCCs confirmed by operation and pathology from May 2013 to May 2018.A single large ROI (about 2/3 of the area of the tumor) was used to measure the unenhanced CT values of 98 RCCs. Statistical differences in RCC unenhanced CT values of different pathological types were then analyzed. RCC masses with uniform density and CT value ≤ 20 HU was re-measured with multiple (≥ 6) uniformly distributed small ROI (≤0.6 cm2). Results Measured by single large ROI, the average CT value of 98 RCCs were (30.9±9.4) HU, (28.3±8.6) HU for 56 clear cell tumors, (34.2±10.1) HU for 28 papillary tumors, and (35.1±9.2) HU for 14 chromophobe tumors (P=0.06). Of 98 RCCs, 25 cases were lower than 20 HU. Of these, 21 appeared heterogeneous and 4 appeared homogeneous. Using multiple small ROIs, these 4 RCCs revealed maximum attenuation values above 20 HU (range: 25-32 HU). Conclusion RCC can measure 20 HU or less at unenhanced CT when a single large ROI is used. While most appear heterogeneous, some may appear homogeneous, but will likely reveal CT values greaterthan 20 HU when multiple small ROIs were used. This may prevent some RCCs from being misdiagnosed as cysts on unenhanced CT.