[Magnetic resonance imaging of seminal vesicles. Normal and pathological aspects]

We have studied the normal and pathological aspects of seminal vesicles by MRI with body coil by correlation between imaging and pathologic findings after radical surgery of 63 patients with urogenital carcinoma. On normal T2 weighted sequence, the ampulla of the was deferens visible in 71% of cases exhibited a nodular low signal intensity. Seminal vesicles demonstrated an hypersignal in 79%, a low signal intensity in 19% and an heterogeneous signal intensity in 2%. Overall accuracy for the diagnosis of invasion was 77%. MRI was not efficient for bladder carcinoma (sensitivity: 1; specificity: 82%) but it was always gross infiltration (superior to 5 mm) than for prostatic carcinoma (sensitivity: 40%; specificity: 67%). The numerous false positives (15 cases) were related to hypointense normal (8 cases) or fibrous (6 cases) seminal vesicles and one case of atrophy. The false negatives were related to small invasion. Only, the negative predictive value was good value (overall NPV: 96%; bladder carcinoma NPV: 1; prostatic carcinoma NPV: 89%). A normal bilateral hypersignal of seminal vesicles permit to eliminate a gross invasion.