BERKELEY, CA (UroToday.com) - The ideal radiographic imaging for evaluating prostate cancer would accurately identify which men had extracapsular extension (ECE) and/or seminal vesicle involvement (SVI) so that appropriate decisions could be made about tumor resectability and the ability to perform nerve-sparing prostatectomy.
Newer imaging techniques with magnetic resonance imaging (spectroscopy, dynamic contrast enhancement, diffusion-weighted imaging) are on the horizon but are not yet widely available. We sought to evaluate the performance of readily available imaging technology, MRI with endrorectal coil (ER-MRI), in accurately staging patients compared to the findings at subsequent radical prostatectomy.
At the University of Iowa, Dr. Richard Williams regularly obtained ER-MRI in patients with risk factors (Gleason grade ≥ 4+3, PSA ≥ 10 ng/ml, suspicious rectal exam, or extensive biopsy core involvement). We retrospectively reviewed 94 men with an ER-MRI and compared the reported results to the subsequent prostatectomy specimen. Three men with node-positive disease had prostatectomy aborted and were excluded from the concordance evaluation and seven additional men were found to have node-positive disease. None of these 10 node-positive men had lymphadenopathy on ER-MRI. Only a minority of patients were found to actually have adverse pathologic features at prostatectomy (24% ECE, 9% SVI). Comparing ER-MRI results to subsequent prostatectomy specimen, the results (accuracy, positive predictive value, negative predictive value, sensitivity, specificity) were 70%, 27%, 76%, 14%, 88%, respectively, for ECE. Thus, 73% of men thought to have ECE actually did not have pathologic ECE and 86% of pathologic ECE was not identified by ER-MRI. The predictive result for ECE was extremely limited as the subsequent pathologic rate of ECE was 27% when ECE was predicted on ER-MRI compared to 24% when no ECE was seen. The results were better for predicting SVI at 93%, 75%, 94%, 38%, 99% for accuracy, positive predictive value, negative predictive value, sensitivity, and specificity, respectively.
Our results support caution in interpreting the results of ER-MRI for staging prostate cancer. ER-MRI provides more information than would be available from CT scan, but the results must be interpreted with the knowledge that there is only moderate concordance between imaging findings and subsequent prostatectomy.
Kenneth Nepple, MD as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.