Intercenter reproducibility of software-based fusion biopsies for grade group prediction when targeting suspicious MRI lesions

Abstract

Purpose: To assess the intercenter reproducibility of software-based fusion targeted biopsy (TB) for grade-group assessment and pretherapeutic evaluation of highly suspicious MRI lesions.

Patients and methods: In this study, were included 380 consecutive patients who underwent radical prostatectomy (RP) after prostate cancer diagnosis and a prebiopsy MRI showing Prostate Imaging-Reporting and Data System (PIRADS) score 4 or 5 lesions. All patients underwent systematic biopsies (SB) combined with software-based fusion TB in the 2 centers. Biopsies were only performed by expert urologists or radiologists in a contemporary time frame. The primary endpoint was the center difference of concordance/upgrading rates between biopsy and RP specimens.

Results: Pathological features on biopsy and RP specimens were significantly different among centers with more unfavourable disease in center 1. The rate of TB upgrading was 33.6% in center 1 vs. 35.4% (P = 0.860) in center 2. Grading concordance was also comparable among centers (50.0% vs. 47.1%) as well as the SB upgrading rate. Regression analysis did not find any baseline characteristics (Age, prostate-specific antigen, MRI lesions, center) predictive for TB upgrading. These findings were achieved by using fewer TB per lesion in center 1 (2.3 vs. 5.0, P < 0.001), at the expense of more SB cores (14.4 vs. 8.5, P < 0.001). The influence of MRI characteristics (lesion size and number, PIRADS score) on upgrading rates was consistent among centers.

Conclusions: Software-based fusion TB technique leads to comparable outcomes in terms of grade group prediction accuracy in PIRADS 4 to 5 lesions, insignificant between centers, in spite of different non imaging-based aggressiveness features.

Keywords: MRI; Prostate cancer; Radical prostatectomy; Systematic biopsies; Targeted biopsies.