Multiphasic multidetector CT aids renal cell carcinoma differentiation
medwireNews: Multiphasic multidetector computed tomography (CT) may help clinicians discriminate clear cell renal cell carcinoma (ccRCC) from oncocytoma, papillary RCC, and chromophobe RCC, study findings suggest.
"Because clear cell RCCs have a poorer prognosis and a greater likelihood of metastasis than do the three other groups, a noninvasive means of discriminating between these groups can be of great clinical value," say Jonathan Young (University of California, Los Angeles, USA) and colleagues.
They found that enhancement on multiphasic multidetector CT was able to distinguish ccRCC from oncocytoma, papillary RCC, and chromophobe RCC with accuracies of 77% (83 out of 108 patients), 85% (101 of 119 patients), and 84% (81 of 97 patients).
A total of 298 renal lesions were studied, of which 170 (57%) were ccRCCs, 49 (16%) were oncocytomas, 57 (19%) were papillary RCCs, and 22 (7%) were chromophobe RCCs.
CT examination showed that mean enhancement peaked in the corticomedullary phase for both ccRCCs and oncocytomas, whereas mean enhancement of papillary and chromophobe RCCs peaked in the neurographic phase.
As reported in Radiology, the enhancement of ccRCCs was significantly greater than that of oncocytomas and chromophobe RCCs in the corticomedullary (125 vs 106 and 74 Hounsfield units [HU], respectively) and excretory (80 vs 67 and 69 HU, respectively) phases.
It was also significantly greater than that of the papillary RCCs in the corticomedullary (125 vs 54 HU), nephrographic (103 vs 64 HU), and excretory (80 vs 54 HU) phases.
Based on these findings, the researchers calculated optimal enhancement threshold levels for distinguishing between the lesions. They report that using threshold levels of 106 HU in the corticomedullary phase, 92 HU in the nephrographic phase, and 68 HU in the excretory phase they were able to discriminate ccRCC from oncocytoma with a positive predictive value of 85%.
Similarly, respective threshold levels of 55 HU, 65 GHU, and 55 HU enabled ccRCC to be distinguished from papillary RCC with a positive predictive value of 86%, while thresholds of 75 HU, 85 HU, and 60 HU enabled ccRCC to be distinguished from chromophobe RCC with a positive predictive value of 90%.
They report: "Our results indicate that multiphasic multidetector CT potentially can assist in discriminating between these groups. However, validation in a large prospective trial with use of solely a four-phase protocol is required."
Young and team add that this will "help guide clinical decision making." For instance, "lesions suspected of enhancing like oncocytomas… may lead to preoperative biopsy for confirmation to obviate surgery or to watchful waiting," they say.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Lucy Piper, Senior medwireNews Reporter