Staging of prostate cancer with endorectal MR imaging: lessons from a learning curve

Endorectal magnetic resonance (MR) imaging is the most accurate noninvasive method of staging prostate cancer. However, inexperienced radiologists may lack the necessary technical and interpretative skills to use this technique, and both radiologists and referring urologists may become frustrated with this method because of its inaccuracy compared with analysis of the radical prostatectomy specimen. Meticulous pathologic correlation is necessary to evaluate endorectal MR imaging findings. The authors compare their initial experience using endorectal MR imaging for staging prostate cancer (25 cases) with their later experience (25 cases) to highlight the various diagnostic pitfalls and "pearls" one may encounter when using endorectal MR imaging. Knowledge of the pathways of tumor spread inside and outside the gland may be helpful in interpreting endorectal MR images. The authors achieved a substantial improvement in the overall staging accuracy of endorectal MR imaging by careful pathologic correlation and by considering the anatomic features of prostate cancer.