Transperineal Mri–ultrasound Fusion-Guided Prostate Biopsy Using the Koelis Trinity System: Diagnostic Outcomes and Initial Experience in a Six-Patient Case Series

Background: Transperineal magnetic resonance imaging–ultrasound (MRI–US) fusion-guided prostate biopsy has emerged as an important diagnostic approach for patients with suspected prostate cancer. The technique enables targeted sampling of suspicious lesions identified on multiparametric MRI (mpMRI), while the transperineal route offers favorable access to anterior prostatic regions and a reduced risk of infectious complications. Objective: To describe the initial diagnostic outcomes and procedure-related complications of transperineal MRI–US fusion-guided prostate biopsy using the KOELIS Trinity system in a six-patient case series. Materials and Methods: Six patients with suspicious lesions on prostate mpMRI underwent transperineal MRI–US fusion-guided prostate biopsy using the KOELIS Trinity platform under general anesthesia. Clinical, radiological, and histopathological data were analyzed descriptively. The principal outcome was histologically confirmed prostate cancer. Secondary outcomes included the distribution of biopsy findings according to PI-RADS classification and reported procedural complications. Results: The mean patient age was 64.8 ± 7.3 years, with a mean PSA level of 11.05 ± 4.43 ng/mL and a mean prostate volume of 75.2 ± 33.0 mL. One patient (16.7%) had a PI-RADS 3 lesion, two (33.3%) had PI-RADS 4 lesions, and three (50.0%) had PI-RADS 5 lesions. Prostatic adenocarcinoma was detected in two patients (33.3%), both classified as International Society of Urological Pathology (ISUP) grade group 1. Four patients (66.7%) had benign histopathological findings consistent with benign prostatic hyperplasia. No clinically significant prostate cancer (ISUP grade group ≥2) was identified. Two of the three PI-RADS 5 lesions yielded benign histopathological findings. Postprocedural hematuria was reported in one patient, while four patients had no reported complications. Complication information was unavailable for one patient. Conclusion: This preliminary case series describes the clinical application of transperineal MRI–US fusion-guided prostate biopsy using the KOELIS Trinity system. The findings highlight radiological–histopathological discordance in some highly suspicious lesions and the importance of clinical follow-up after benign targeted biopsy results. Larger prospective studies with standardized biopsy protocols and longitudinal follow-up are required to assess diagnostic performance and safety.