Introduction

The aim of this study was to evaluate the accuracy of magnetic resonance imaging (MRI) scoring system for prostate cancer detection in the peripheral zone (PZ) and the transition zone (TZ) using MRI/trans-rectal ultrasonography (US) fusion targeted biopsy as a reference standard.

Methods

We retrospectively reviewed 762 patients who underwent 3-Tesla multi-parametric (mp)-MRI and the following MRI/US fusion targeted biopsy, all of which were performed by experienced urologists (10/2012-8/2015). We excluded patients in whom MRI did not identify any suspicious lesions and radiologists who reported in less than 50 cases. Finally, 648 patients with 1255 suspicious lesions were included in this study. The mp-MRIs were reported on a 5-point Likert scale of suspicion. The UroStation^® (Koelis, France) was used for the image fusion. Clinically significant cancer was defined as biopsy Gleason score ≥7.

Results

Median age was 64 years, pre-biopsy prostate-specific antigen (PSA) level was 6.93 ng/ml and estimated prostate volume was 52.1 ml. _x000D_ Of 1255 suspicious lesions on MRI, 62.4% (n=783) were located in the PZ and 19.5% (n=245) in the TZ. _x000D_ There was no significant difference in the proportion of 5-point suspicious grades between the PZ and the TZ (p=0.077)._x000D_ In comparison between the PZ and the TZ, there was no significant difference in overall cancer detection rate in grade 1-2 lesions (11.8% vs 15.1%, p=0.362), grade 3 lesions (26.9% vs 19.8%, p=0.163) and grade 4-5 lesions (55.4% vs 50.0%, p=0.551)._x000D_ Regarding clinically significant cancer detection rate, there was no significant difference in grade 1-2 lesions between the PZ and the TZ (3.1% vs 6.6%, p=0.087). In contrast, statistical differences were noted in grade 3 lesions (15.1% vs 5.9%, p=0.019) and grade 4-5 lesions (45.9% vs 23.7%, p=0.013) between the PZ and the TZ. _x000D_

Conclusions

The diagnostic reliability of mp-MRI for detecting clinically significant cancer in the TZ was less than that in the PZ. Although grade 3 lesions in the TZ showed similar overall cancer detection rate compared to that in the PZ, clinically significant cancer detection rate of grade 3 lesions in the TZ was quite lower than that in the PZ. Improvement of radiologist's interpretation, grading system itself, or targeting technique for grade 3 lesions in the TZ should be re-considered.

Funding

none