Kim Jeong Kon, Park Soo-Youn, Shon Jeong-Hee, Cho Kyoung-Sik
Department of Radiology, Asan Medical Center, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, Korea.
Radiology. 2004 Mar;230(3):677-84. doi: 10.1148/radiol.2303030003.
To compare various computed tomographic (CT) features of angiomyolipoma (AML) with minimal fat with those of size-matched renal cell carcinoma (RCC).
Eighty-one patients (19 with AML with minimal fat [mean diameter, 2.8 cm; range, 1.5-4.5 cm] and 62 with RCC [mean diameter, 3.1 cm; range, 1.8-4.5 cm]) who had undergone biphasic CT (ie, CT with unenhanced, corticomedullary, and early excretory phase scanning) were evaluated. Two reviewers who were unaware of the diagnosis retrospectively recorded tumor attenuation on unenhanced scans, enhancement characteristics (ie, homogeneity of enhancement, amount of enhancement, enhancement pattern over time), tumor margin, location of tumor center, intratumoral calcification, perinephric changes, and patient age and sex. The predictive value of each CT finding was determined by using multivariate logistic regression analysis.
Homogeneous enhancement (observed in 79% of AMLs vs 5% of RCCs; odds ratio, 37) and prolonged enhancement pattern (observed in 58% of AMLs vs 10% of RCCs; odds ratio, 42) were valuable predictors for differentiating AML with minimal fat from RCC at multivariate analysis (P <.05 for both). When both CT findings were used as a criterion for differentiating AML from RCC, positive and negative predictive values were 91% (10 of 11 tumors) and 87% (61 of 70 tumors), respectively. Fifty-three percent of AMLs versus 13% of RCCs showed high tumor attenuation on unenhanced scans (P =.04), whereas RCCs showed greater mean enhancement than AMLs (114 HU +/- 44 [SD] vs 73 HU +/- 30 in corticomedullary phase and 66 HU +/- 24 vs 49 HU +/- 20 in early excretory phase) and a male predominance (male-to-female ratio, 50:12 vs 8:11; P =.001).
Biphasic helical CT may be useful in differentiating AML with minimal fat from RCC, with homogeneous tumor enhancement and prolonged enhancement pattern being the most valuable CT findings.
比较含少量脂肪的血管平滑肌脂肪瘤（AML）与大小匹配的肾细胞癌（RCC）的各种计算机断层扫描（CT）特征。
对81例接受双期CT（即平扫、皮质髓质期和早期排泄期扫描的CT）检查的患者进行评估，其中19例为含少量脂肪的AML（平均直径2.8 cm；范围1.5 - 4.5 cm），62例为RCC（平均直径3.1 cm；范围1.8 - 4.5 cm）。两名不知诊断结果的阅片者回顾性记录平扫时肿瘤的密度、强化特征（即强化的均匀性、强化程度、强化随时间的模式）、肿瘤边缘、肿瘤中心位置、瘤内钙化、肾周改变以及患者的年龄和性别。通过多因素逻辑回归分析确定每个CT表现的预测价值。
多因素分析显示，均匀强化（79%的AML出现，5%的RCC出现；优势比为37）和强化模式持续时间长（58%的AML出现，10%的RCC出现；优势比为42）是鉴别含少量脂肪的AML与RCC的有价值的预测指标（两者P均<0.05）。当将这两个CT表现作为鉴别AML与RCC的标准时，阳性预测值和阴性预测值分别为91%（11个肿瘤中的10个）和87%（70个肿瘤中的61个）。53%的AML与13%的RCC在平扫时表现为肿瘤密度高（P = 0.04），而RCC的平均强化程度高于AML（皮质髓质期：114 HU±44[标准差]对73 HU±30；早期排泄期：66 HU±24对49 HU±20），且以男性为主（男女性别比：50:12对8:11；P = 0.001）。
双期螺旋CT有助于鉴别含少量脂肪的AML与RCC，肿瘤均匀强化和强化模式持续时间长是最有价值的CT表现。
