Targeted MRI-guided prostate biopsy: are two biopsy cores per MRI-lesion required?

Purpose: This study evaluates the feasibility of performing less than two core biopsies per MRI-lesion when performing targeted MR-guided in-bore prostate biopsy.

Methods: Retrospectively evaluated were 1545 biopsy cores of 774 intraprostatic lesions (two cores per lesion) in 290 patients (66 ± 7.8 years; median PSA 8.2 ng/ml) regarding prostate cancer (PCa) detection, Gleason score, and tumor infiltration of the first (FBC) compared to the second biopsy core (SBC). Biopsies were acquired under in-bore MR-guidance.

Results: For the biopsy cores, 491 were PCa positive, 239 of 774 (31 %) were FBC and 252 of 771 (33 %) were SBC (p = 0.4). Patient PCa detection rate based on the FBC vs. SBC were 46 % vs. 48 % (p = 0.6). For clinically significant PCa (Gleason score ≥4 + 3 = 7) the detection rate was 18 % for both, FBC and SBC (p = 0.9). Six hundred and eighty-seven SBC (89 %) showed no histologic difference. On the lesion level, 40 SBC detected PCa with negative FBC (7.5 %). Twenty SBC showed a Gleason upgrade from 3 + 3 = 6 to ≥3 + 4 = 7 (2.6 %) and 4 to ≥4 + 3 = 7 (0.5 %).

Conclusion: The benefit of a second targeted biopsy core per suspicious MRI-lesion is likely minor, especially regarding PCa detection rate and significant Gleason upgrading. Therefore, a further reduction of biopsy cores is reasonable when performing a targeted MR-guided in-bore prostate biopsy.

Key points: • Higher PI-RADS overall score (IV-V) correlated well with PCa detection rate • In more than 80 % SBC was concordant regarding overall PCa detection • In almost 90 % there was no Gleason upgrading by the SBC • Only 2/54 (3.7 %) csPCa was missed when the SBC was omitted • For IB-GB a further reduction of biopsy cores is reasonable.