Kim Ji Yeon, Kim Jeong Kon, Kim Namkug, Cho Kyoung-Sik
Department of Radiology, Asan Medical Center, University of Ulsan, 388-1 Poongnap-dong, Songpa-gu, Seoul 138-736, Korea.
Radiology. 2008 Feb;246(2):472-9. doi: 10.1148/radiol.2462061312. Epub 2007 Dec 19.
To retrospectively evaluate the diagnostic performance of computed tomographic (CT) histogram analysis for differentiating angiomyolipoma (AML) without visible fat from renal cell carcinoma (RCC) at CT, by using pathologic analysis and clinical diagnosis as the reference standard.
This retrospective study was approved by the institutional review board; informed consent was waived. The authors reviewed the medical records of 144 patients with pathologic confirmation of RCC or AML (105 men, 39 women; mean age, 52 years). Analysis of unenhanced CT histograms was performed on 34 AMLs without visible fat at CT and 110 size-matched RCCs. The percentages of voxels and pixels were compared in the two groups according to the CT number categories. The diagnostic performance of CT histogram analysis in differentiating AML from RCC was determined by using receiver operating characteristic (ROC) analysis.
The percentages of voxels and pixels with a CT number less than -30 HU (2.7% and 3.4% vs 0.1% and 0.0%), less than -20 HU (4.3% and 5.1% vs 0.2% and 0.1%), less than -10 HU (7.0% and 8.1% vs 0.6% and 0.4%), and less than 0 HU (12.0% and 13.9% vs 2.0% and 2.0%) were significantly greater in the AML group than in the RCC group (P < .01), respectively. The area under the ROC curve was as high as 0.706 when a pixel percentage with a CT number less than -10 HU was used as a differentiating parameter. Corresponding to the specificity of 100% for differentiating AML from RCC, the sensitivity was as high as 20% when a pixel percentage of 6% with a CT number less than -10 HU was used as a criterion.
CT histogram analysis may be useful for differentiating AML without visible fat from RCC at CT.
以病理分析和临床诊断作为参考标准，回顾性评估计算机断层扫描（CT）直方图分析在CT上鉴别无可见脂肪的血管平滑肌脂肪瘤（AML）与肾细胞癌（RCC）的诊断性能。
本回顾性研究经机构审查委员会批准；无需知情同意。作者回顾了144例经病理证实为RCC或AML患者的病历（男性105例，女性39例；平均年龄52岁）。对34例CT上无可见脂肪的AML和110例大小匹配的RCC进行了平扫CT直方图分析。根据CT值类别比较两组体素和像素的百分比。采用受试者操作特征（ROC）分析确定CT直方图分析在鉴别AML与RCC中的诊断性能。
AML组CT值小于-30 HU（2.7%和3.4% vs 0.1%和0.0%）、小于-20 HU（4.3%和5.1% vs 0.2%和0.1%）、小于-10 HU（7.0%和8.1% vs 0.6%和0.4%）以及小于0 HU（12.0%和13.9% vs 2.0%和2.0%）的体素和像素百分比分别显著高于RCC组（P <.01）。当使用CT值小于-10 HU的像素百分比作为鉴别参数时，ROC曲线下面积高达0.706。对应于鉴别AML与RCC的特异性为100%，当使用CT值小于-10 HU的像素百分比为6%作为标准时，敏感性高达20%。
CT直方图分析可能有助于在CT上鉴别无可见脂肪的AML与RCC。
