Background: We aim to evaluate the correlation between multiparametric prostate MRI (MP-MRI) suspicion for seminal vesicle invasion (SVI) and pathology on MRI/US fusion-guided biopsy, as well as radical prostatectomy (RP). Methods: 822 patients underwent MP-MRI and MRI/US fusion-guided biopsy. 24 patients underwent targeted seminal vesicle biopsies. 5 patients had MRI findings suspicious for bilateral SVI, for a total of 29 lesions. MP-MRI targets were scored as low, moderate, or high suspicion for PCa involvement according to the validated NIH scoring system. Patient demographics were reviewed and positive predictive values (PPVs) of pre-biopsy suspicion levels were calculated with respect to correlative biopsy pathology and final RP pathology. Results: At the time of MP-MRI, the median age was 64 years with a median PSA of 10.74 ng/ml (Table). Thirteen (54.2%) had not been previously diagnosed with PCa. Of the 29 SV lesions on imaging, MP-MRI suspicions of low, moderate, and high were assigned to 3, 18, and 8 lesions, respectively. The PPVs of these MRI suspicion levels, confirmed by MRI/US fusion biopsy, were 0%, 77.7%, and 62.5%, respectively. The 3 patients in the low suspicion cohort all underwent RP, confirming targeted biopsy findings. Of those with moderate or high suspicion of SVI on MP-MRI, only 5 underwent RP, with a targeted biopsy accuracy of 80%. The overall accuracy of targeted SV biopsy was 87.5% (7/8) on final RP pathology. Conclusions: MP-MRI suspicion of SVI correlates highly with findings on targeted SV biopsy and final RP pathology, thus potentially playing a vital role in future preoperative staging for PCa.

¹ Gleason 3+4 through 10. ² Gleason 4+4 through 10.