AUA 2017: Prediction of Histological Subtypes of Small Renal Masses: Striving for a Standardized MRI Diagnostic Algorithm

Boston, MA (UroToday.com) Fernando Kay and colleagues from UT Southwestern Medical Center in Dallas, TX presented their results of MRI characteristics of small renal masses for predicting pathologic histology this morning at the 2017 AUA Annual Meeting’s Uroradiology poster session. With improved cross-sectional abdominal imaging, as well as patients that may have a contraindication to CT imaging, studies assessing MRI imaging characteristics for predicting benign vs malignant lesions are important.

In this study, there were 109 patients with cT1a small renal masses who underwent a preoperative MRI that was assessed by one of 7 radiologists with specific MRI training. Pathologic histology included 51% with clear cell renal cell carcinomas (ccRCC), 25% with papillary RCC (pRCC), 6% with chromophobe RCC (chrRCC), 6% with oncocytoma, 6% with minimal-fat angiomyolipoma (mfAML), and 9% comprising other histology. In terms of histology specific MRI characteristics on multivariable analysis, the authors noted that ccRCC was predicted by signal intensity on T2W (high vs low, OR: 3.2, 95%CI 1.4-7.1) and contrast avidity (avid vs. low, OR: 4.5, 95%CI 1.8-10.8). pRCC was predicted by contrast avidity (low vs avid, OR: 0.05, 95%CI 0.02-0.2), and segmental enhancement inversion was an independent predictor of oncocytoma (present vs absent, OR: 16.2, 95%CI 1.0-275.4). Possible limitations of the study include no information comparing renal mass biopsy histology to MRI characteristics, as well as a relatively small sample size when stratified by histology, leading to large confidence intervals for the multivariable analysis.

The authors concluded that the use of T2W signal intensity and contrast avidity are critical steps in the implementation of standardized MRI interpretation algorithms for predicting the histological subtype of small renal masses. Additionally, the importance of specialized MRI trained radiologists should not be understated when assessing the intricacies of MRI features for delineating small renal mass histology.

Presented By: Fernando U. Kay, UT-Southwestern Medical Center, Dallas, TX, USA

Co-Authors: Noah E. Canvasser, Yin Xi, Daniella F Pinho, Daniel Costa, Alberto Diaz de Leon, Gaurav Khatri, John R. Leyendecker, Takeshi Yokoo, Aaron Lay, Nicholas Kavoussi, Ersin Koseoglu, Jeffrey A. Cadeddu, Ivan Pedrosa

Written By: Zachary Klaassen, MD, Urologic Oncology Fellow, University of Toronto, Princess Margaret Cancer Centre
Twitter: @zklaassen_md

at the 2017 AUA Annual Meeting - May 12 - 16, 2017 – Boston, Massachusetts, USA

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