A new sign for detection of extracapsular extension of prostatic adenocarcinoma: sum of positive sextants per lobe combining interpretation of magnetic resonance imaging and prostate biopsy results

Background: The objective of this study was to assess the possibility of improving the reliability of preoperative detection of extracapsular extension (ECE) in each prostate lobe by using a new sign called sum of positive sextants per lobe (SPS-L), combining interpretation of MRI and prostate biopsy results.

Patients and methods: We reviewed the charts of 590 patients undergoing radical prostatectomy between 2002 and 2007. All patients were assessed by preoperative 1.5 Tesla MRI using an integrated endorectal and pelvic phased array coil. A sextant was defined as "positive" when tumor infiltration was observed on a biopsy sample or a pathologic image was observed on MRI (0 = absent, 1 = present). A score, called sum of positive sextants per lobe (SPS-L), was defined as the sum of positive sextants on biopsy samples and positive sextants on MRI (MRI-L) for each lobe. A second score taking into account the presence or absence of ECE visualized on MRI (T3 MRI-L + SPS-L) was also tested for the detection of ECE per lobe.

Results: On multivariate analysis, the SPS-L and T3 MRI-L + SPS-L scores were significantly higher in the presence of ECE and extensive ECE (P < .0001). The areas under receiver operating characteristic (ROC) curves were significantly greater for the T3 MRI-L + SPS-L score than for the positive biopsy result per lobe (PB(+)/L) rate (P < .0001).

Conclusion: The use of indirect signs (SPS-L) associated with direct signs (T3 MRI) allows the preoperative detection of ECE per lobe by endorectal 1.5 Tesla MRI with high sensitivity.