Use of Histogram Analysis in Diffusion-Weighted Magnetic Resonance Imaging for Differentiation of Renal Tumor Subgroups

Abstract

Background: The histopathological differentiation of renal neoplasms can be challenging via imaging. Objectives: To evaluate differences in histogram parameters on apparent diffusion coefficient (ADC) maps and to investigate the efficacy of histogram analysis in differentiation of oncocytomas from malignant renal neoplasm (MRN) subgroups. Patients and Methods: In this cross-sectional, retrospective study, the texture parameters of diffusion-weighted magnetic resonance images (DW-MRI) were evaluated in 65 patients with renal tumors (nine cases of oncocytoma and 59 cases of MRN) for a histological analysis. Results: A total of 68 lesions from 50 male and 15 female patients, with a median age of 55.4 years, were examined in this study. There were significant differences in the mean, median, and peak ADC values, as well as ADC percentiles, between the oncocytoma and MRN subgroups. Regarding the histopathological features of the lesions, 9 (11.5%) cases of oncocytomas, 23 (29.5%) cases of clear cell renal carcinoma (ccRCC), 14 (17.9%) cases of papillary renal cell carcinoma (pRCC), 12 (15.4%) cases of chromophobe renal cell carcinoma (chRCC), and 10 (12.8%) other tumors (including four cases of transitional cell carcinoma, four cases of non-Hodgkin’s lymphoma, and two cases of primitive neuroectodermal tumor) were identified. Significant differences were found in the mean and median ADC values between the oncocytoma, pRCC, chRCC, and other MRN subgroups. Moreover, significant differences were found in the mean and median ADC values between the ccRCC, pRCC, and chRCC subgroups. There were also significant differences in the percentiles of mean and median ADCs between oncocytomas and pRCC, chRCC, and other MRN subgroups. However, there were no significant differences in the mean and median ADCs (including the percentile histogram analysis) or the peak ADC between the oncocytoma and ccRCC groups. The mean, median, and percentile of ADC for renal masses were superior to kurtosis, skewness, and entropy. Conclusion: Although differentiation between ccRCC and oncocytoma was not possible by only measuring the mean, median, and peak ADC values, the histogram analysis of ADCs may improve differentiation between the MRN subgroups. Clearly, ADC cannot be used to differentiate between oncocytomas and MRNs.