Clinically low-risk prostate cancer: evaluation with transrectal doppler ultrasound and functional magnetic resonance imaging

ABSTRACT

OBJECTIVES: To evaluate transrectal ultrasound, amplitude Doppler ultrasound, conventional T2-weighted magnetic resonance imaging, spectroscopy and dynamic contrast-enhanced magnetic resonance imaging in localizing and locally staging low-risk prostate cancer. INTRODUCTION: Prostate cancer has been diagnosed at earlier stages and the most accepted classification for low-risk prostate cancer is based on clinical stage T1c or T2a, Gleason score <6, and prostate-specific antigen (PSA) <10 ng/ml. METHODS: From 2005 to 2006, magnetic resonance imaging was performed in 42 patients, and transrectal ultrasound in 26 of these patients. Seven patients were excluded from the study. Mean patient age was 64.94 years and mean serum PSA was 6.05 ng/ml. The examinations were analyzed for tumor identification and location in prostate sextants, detection of extracapsular extension, and seminal vesicle invasion, using surgical pathology findings as the gold standard. RESULTS: Sixteen patients (45.7 percent) had pathologically proven organ-confined disease, 11 (31.4 percent) had positive surgical margin, 8 (28.9 percent) had extracapsular extension, and 3 (8.6 percent) presented with extracapsular extension and seminal vesicle invasion. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy values for localizing low-risk prostate cancer were 53.1 percent, 48.3 percent, 63.4 percent, 37.8 percent and 51.3 percent for transrectal ultrasound; 70.4 percent, 36.2 percent, 65.1 percent, 42.0 percent and 57.7 percent for amplitude Doppler ultrasound; 71.5 percent, 58.9 percent, 76.6 percent, 52.4 percent and 67.1 percent for magnetic resonance imaging; 70.4 percent, 58.7 percent, 78.4 percent, 48.2 percent and 66.7 percent for magnetic resonance spectroscopy; 67.2 percent, 65.7 percent, 79.3 percent, 50.6 percent and 66.7 percent for dynamic contrast-enhanced magnetic resonance imaging, respectively. Sensitivity, specificity, PPV, NPV and accuracy values for detecting extracapsular extension were 33.3 percent, 92 percent, 14.3 percent, 97.2 percent and 89.7 percent for transrectal ultrasound and 50.0 percent, 77.6 percent, 13.7 percent, 95.6 percent and 75.7 percent for magnetic resonance imaging, respectively. For detecting seminal vesicle invasion, these values were 66.7 percent, 85.7 percent, 22.2 percent, 97.7 percent and 84.6 percent for transrectal ultrasound and 40.0 percent, 83.1 percent, 15.4 percent, 94.7 percent and 80.0 percent for magnetic resonance imaging. CONCLUSION: Although preliminary, our results suggest that imaging modalities have limited usefulness in localizing and locally staging clinically low-risk prostate cancer.