Seminal vesicle invasion: accuracy and analysis of infiltration patterns with high-spatial resolution T2-weighted sequences on endorectal magnetic resonance imaging.

OBJECTIVE: To evaluate the accuracy of high-spatial resolution T2-weighted endorectal magnetic resonance imaging (eMRI) for detection and pattern depiction of seminal vesicle invasion (SVI) in patients with prostate cancer (PCa). METHODS: 376 patients were included who underwent eMRI for staging before radical open prostatectomy at 1.5 T with an endorectal coil. Statistical accuracy for detection of SVI was calculated. MR images of patients with SVI were further evaluated by two radiologists according to the classification by Wheeler and Ohori. RESULTS: In the cohort, 35 patients had SVI after histopathological evaluation of the prostatectomy specimen (stage pT3b). Sensitivity and specificity for detection of SVI were 48.6 and 97.7%, respectively. Negative and positive predictive values and overall accuracy were 94.9, 68.0, and 93.1%, respectively. Infiltration pattern analysis showed that type I invasion was most common with 48.6 followed by type IIa (31.4%) and IIb (20%). Type III was not present. There was no statistical significant difference between the three groups regarding Gleason score, age, and prostate-specific antigen level. CONCLUSIONS: eMRI with high-spatial resolution T2-weighted imaging is accurate for assessment of SVI. Depiction of different infiltration types of SVI is feasible. By adding information about the extent of SVI, diagnostic reporting and risk stratification could be improved.