Use of Iodine Concentration in the Lipid-Poor Portion of the Renal Mass for Differentiation of Angiomyolipoma from Renal Cell Carcinoma.

Purpose: This study is aimed to evaluate the iodine concentration in the lipid-poor portion of the renal mass as a potential tool for the differentiation between angiomyolipoma (AML) and renal cell carcinoma (RCC). Materials and Methods: There were eight cases of AML and eight cases of RCC. All patients received corticomedullary, nephrographic and excretory phase enhanced scanning. The regions of interest (ROI) were manually placed in the lipid-poor portion of the renal mass and in the abdominal aorta. Average iodine concentrations were obtained for the ROIs and abdominal aorta. Data were compared using repeated measures analysis with the Bonferroni correction for multiple comparisons. Results: At the unenhanced phase, the iodine concentration in the lipid-poor portion of the renal mass of RCC was not significantly different from that of AML (p = 0.298). At the three enhanced phases, the iodine concentrations in the renal mass of RCC were substantially elevated compared with those of AML. In addition, the CT values of the renal mass of RCC were significantly higher than those of AML at all the enhanced phases. Of note, there was a significant correlation between iodine concentrations and CT values (r = 0.919; p < 0.001) in the lipid-poor portion of the renal mass of RCC. Conclusions: Between RCC and AML there was significant difference in iodine concentrations in the lipid-poor portion of the renal masses. Iodine concentration holds promise as a diagnostic alternative to macroscopic fat for differentiation of AML from RCC.