Wang L et al. (2007) Prediction of seminal vesicle invasion in prostate cancer: incremental value of adding endorectal MR imaging to the Kattan nomogram. Radiology 242: 182–188

Although the prevalence of seminal vesicle invasion (SVI) in men with prostate cancer is low, such individuals have an increased risk of lymph-node metastasis and tumor recurrence. Preoperative detection of SVI can determine whether patients should undergo radiation therapy or surgery, and can assist prediction of patient outcomes. The Kattan nomogram is used to select patients for adjuvant treatment on the basis of variables that are associated with an increased risk of SVI (serum PSA level, biopsy results, and clinical stage).

Wang and colleagues' retrospective study assessed data from 573 men with prostate cancer (mean age 58.3 years), who underwent preoperative endorectal MRI and radical retropubic prostatectomy with pelvic lymphadenectomy. None received preoperative radiotherapy or hormone ablation. The Kattan nomogram was used to estimate the risk of SVI, and histopathologic analysis confirmed SVI in 4.9% of the patients.

Preoperative endorectal MRI findings strongly correlated with the presence of SVI on univariate and multivariate analysis. The addition of endorectal MRI to the Kattan nomogram resulted in a valuable incremental improvement in its performance—the area under the receiver operating characteristic curve was markedly greater for endorectal MRI plus the Kattan nomogram (0.87) than for either technique alone (nomogram only 0.80, MRI only 0.76).

Wang and colleagues suggest that technological advances in MRI, as well as urologists' and radiologists' increased experience with prostate MRI, have contributed to its increased value in the preoperative evaluation of men with prostate cancer.