Estimation of prostate cancer volume by endorectal coil magnetic resonanceimaging vs. pathologic volume

Objective: Since tumor volume is recognized as an important predictor of cl inical stage and disease outcome of prostate cancer, accurate preoperative estimation of tumor volume can play an important role in planning the appro priate treatment and establishing a patient's prognosis. We performed this study to evaluate the accuracy of the endorectal coil magnetic resonance (N IR) technique for reliable prediction of tumor volume in patients with pros tatic cancer, Material and Methods: Endorectal coil MR imaging was performe d in 57 consecutive men who were suspected to have prostate cancer. Subsequ ent ultrasound-guided transrectal biopsy revealed prostate cancer in 44 cas es. The pathological volume of the surgical specimens of 25 selected patien ts who underwent radical prostatectomy was retrospectively compared to the volume estimated by endorectal coil MR studies, and the Pearson correlation coefficient was calculated. Results: in 15 patients the estimated size of the tumor was within 15% of the true tumor volume; in the remaining 10 case s MR imaging tended to underestimate large tumors and overestimate small on es, A significant correlation between the volumes as determined with MR ima ging and measurements of surgical specimens was observed (r 0.94; slope 0.8 2). To our knowledge, this is the best correlation found between pathologic al volume and tumor volume as evaluated by any other imaging modality. Conc lusions: Endorectal coil MR imaging is a powerful means of evaluating the p rostate gland; however, further improvements in imaging and/or volume calcu lation are required to provide a more accurate preoperative assessment of p rostate cancer volume.