[Does magnetic resonance imaging allow the assessment of the loco-regional extension of cancer of the prostate? Report of 27 anatomo-radiologic comparisons]. / L'imagerie par Résonance Magnétique permet-elle d'apprécier l'extension loco-régionale du cancer de la prostate? A propos de 27 confrontations anatomo-radiologiques.

ABSTRACT

27 patients with histologically proven prostatic carcinoma were investigated by magnetic resonance imaging (MRI) (0.5 Tesla) in order to determine the local spread of the cancer. These patients then underwent ilio-obturator lymph node dissection with frozen section examination, followed by radical prostatectomy. Histological examination of the resection specimens was performed on slides prepared from large transverse sections every 5 mn. The MRI examination was especially designed to confirm the diagnosis of capsular effraction based on the signals of the periprostatic fat (PF), periprostatic venous plexuses (PVP) and seminal vesicles (SV). An abnormality of at least one of these structures was considered to indicate the diagnosis of capsular effraction. The MRI data were compared to the histological findings. The results demonstrated a sensitivity of 62% for the PF signal, 52% for the PVP signal and 40% for the SV signal. The overall MRI-Histology correlation was found to be exact in 23 out of 27 cases (Accuracy = 85%). All of our four errors represented understaging (Sensitivity = 81%). When a rigorous methodology is respected, the high accuracy and sensitivity of MRI makes this modality an investigation of choice for the study of the prostatic capsule, as part of the routine staging of prostatic cancer. It should allow a better selection of patients with intracapsular cancer (T1-2), who constitute candidates for radical treatment.