Purpose: To investigate whether dual-energy multidetector row computed tomographic (CT) imaging with iodine quantification is able to distinguish between clear cell and papillary renal cell carcinoma (RCC) subtypes.
Materials and Methods: In this retrospective, HIPAA-compliant, institutional review board-approved study, 88 patients (57 men, 31 women) with diagnosis of either clear cell or papillary RCC at pathologic analysis, who underwent contrast material-enhanced dual-energy nephrographic phase study between December 2007 and June 2013, were included. Five readers, blinded to pathologic diagnosis, independently evaluated all cases by determining the lesion iodine concentration on color-coded iodine maps. The receiving operating characteristic curve analysis was adopted to estimate the optimal threshold for discriminating between clear cell and papillary RCC, and results were validated by using a leave-one-out cross-validation. Interobserver agreement was assessed by using an intraclass correlation coefficient. The correlation between tumor iodine concentration and tumor grade was investigated.
Results: A tumor iodine concentration of 0.9 mg/mL represented the optimal threshold to discriminate between clear cell and papillary RCC, and it yielded the following: sensitivity, 98.2% (987 of 1005 (95% confidence interval: 97.7%, 98.7%)); specificity, 86.3% (272 of 315 (95% confidence interval: 85.0%, 87.7%)); positive predictive value, 95.8% (987 of 1030 (95% confidence interval: 95.0%, 96.6%)); negative predictive value, 93.7% (272 of 290 (95% confidence interval: 92.8%, 94.7%)); overall accuracy of 95.3% (1259 of 1320 (95% confidence interval: 94.6%, 96.2%)), with an area under the curve of 0.923 (95% confidence interval: 0.913, 0.933). An excellent agreement was found among the five readers in measured tumor iodine concentration (intraclass correlation coefficient, 0.9990 (95% confidence interval: 0. 9987, 0.9993). A significant correlation was found between tumor iodine concentration and tumor grade for both clear cell (τ = 0.85; P < .001) and papillary RCC (τ = 0.53; P < .001).
Conclusion: Dual-energy multidetector CT with iodine quantification can be used to distinguish between clear cell and papillary RCC, and it provides insights regarding the tumor grade.
Written by:
Mileto A, Marin D, Alfaro-Cordoba M, Ramirez-Giraldo JC, Eusemann CD, Scribano E, Blandino A, Mazziotti S, Ascenti G. Are you the author?
Department of Radiology, Duke University Medical Center, Box 3808 Erwin Rd, Durham, NC 27710; Department of Biomedical Sciences and Morphologic and Functional Imaging, Policlinico G. Martino, University of Messina, Messina, Italy; Department of Statistics, North Carolina State University, Raleigh, NC; and Siemens Medical Solutions USA, Malvern, Pa.
Reference: Radiology. 2014 Aug 25:140171.
doi: 10.1148/radiol.14140171
PubMed Abstract
PMID: 25162309