Targeted Renal Biopsy: Predictors on Imaging

Abstract

Objectives The renal nephrometry score uses imaging characteristics such as lesion diameter, location, and proximity to hilar vessels to categorize renal masses by complexity for preoperative planning. These characteristics may also be used to determine the best approach to targeted renal biopsy. This study was conducted to investigate the impact of renal lesion characteristics as measured by the renal nephrometry score on the choice of modality used for performing a targeted renal lesion biopsy and increasing the chance of yielding a diagnostic biopsy. Materials and Methods All targeted computed tomography (CT)/ultrasound-guided renal biopsies performed by our radiology department from January 2017 to February 2020 were reviewed. Radiological characteristics and pathological outcomes were recorded with data on lesion size/ side, location in craniocaudal/anterior–posterior planes, endophytic/exophytic/mixed nature, and skin-lesion distance. Statistical Analysis Chi-squared tests, multivariate analysis, and t-tests were used in this study. Results Of the 145 consecutive patients included in the study, 86.2% (125/145) biopsies were diagnostic. About 54.5% (79/145) biopsies were ultrasound-guided, while 45.5% (66/145) were CT-guided. About 62.1% (90/145) biopsies revealed renal cell carcinoma. The highest rate of diagnostic biopsy was in the exophytic, laterally positioned mass either entirely below lower polar or above upper polar line. Ultrasound was preferred for lesions under 4cm and 4 to 7cm (p = 0.06). CT was used for anterior lesions and ultrasound for posterior and lateral lesions (p < 0.001). Of the 20 nondiagnostic biopsies, 7/20 had a repeat biopsy, 7/20 underwent surveillance, 5/20 underwent partial or total nephrectomy, and 1/20 underwent a pathological lymph node biopsy. Conclusions Our study highlights some factors radiologists should consider when predicting whether CT or ultrasound guidance is more appropriate and the probability of achieving a diagnostic biopsy based on lesion characteristics. At our institution, both modalities achieved high accuracy, although we favored ultrasound in lateral, posterior, and small lesions. These factors should be weighed against local experience and preference.

Keywords

• renal
• lesion
• cancer
• targeted
• biopsy