Accuracy of Sampling PI-RADS 4-5 Index Lesions Alone by MRI-guided In-bore Biopsy in Biopsy-naive Patients Undergoing Radical Prostatectomy

Abstract

Background: Targeting multiparametric magnetic resonance imaging (MP-MRI)-suspicious regions alone in biopsy-naive patients is not common practice, since it may miss clinically significant prostate cancer (PCa).

Objective: To investigate the accuracy of in-bore MRI-guided biopsy of Prostate Imaging Reporting and Data System (PI-RADS) 4 and 5 index lesions alone in biopsy-naive patients undergoing radical prostatectomy (RP).

Design, setting, and participants: A total of 170 patients underwent MRI-guided in-bore biopsy for PI-RADS 4 and 5 index lesions alone between 2013 and 2018, of whom 136 patients were diagnosed with PCa. Fifty-two patients without prior biopsy who underwent RP were included in this study. MP-MRI findings, biopsy results, and whole-mount step-section specimen evaluation were retrospectively analyzed.

Outcome measurements and statistical analysis: Continuous variables were reported as mean (standard deviation) or median (range). Differences in parametric variables were calculated by Student t test.

Results and limitations: Overall International Society of Urological Pathology grade group (GG) up- and downgrading rates were 23.0% and 7.6% per patient and 24.5% and 6.5% per focus, respectively. Ten of 12 biopsy-detected GG 1 foci were upgraded in the final pathology. In 30 patients, a total of 43 different tumor foci were identified outside the sampled index lesion. Average biopsied and nonbiopsied tumor volumes were found to be 2.02 and 0.45 cm³, respectively (p < 0.001). The index lesion was the largest focus of tumor in all patients' final histopathological examination; upgrading was identified in only one nonbiopsied focus in a single patient. Limitations include retrospective design and nonstandard indications of in-bore MRI biopsy.

Conclusions: In-bore MRI-guided biopsy of PI-RADS 4-5 index lesions alone in biopsy-naive patients is a safe and accurate diagnostic modality allowing appropriate patient selection for individualized treatment.

Patient summary: In-bore magnetic resonance imaging-guided prostate biopsy of suspicious lesions alone allows accurate risk stratification of patients and reduces the detection of insignificant prostate cancer.

Keywords: Magnetic resonance imaging–guided in-bore biopsy; Prostate biopsy; Prostate cancer; Radical prostatectomy.