Diagnostic Value of CT in Detecting Peripheral Zone Prostate Cancer

OBJECTIVE. The purpose of this study was to identify the sensitivity of contrast-enhanced CT in detecting high-grade prostate adenocarcinoma. MATERIALS AND METHODS. A retrospective analysis included 100 patients with prostate cancer proven by biopsy between January 2010 and December 2017 who underwent staging CT of the abdomen and pelvis within 3 months of diagnosis. The control subjects were 100 randomly selected aged-matched male outpatients with no known history of malignancy who underwent contrast-enhanced CT of the abdomen and pelvis in the same time period as the patients with cancer. Two readers, blinded to both groups, independently assessed the likelihood of prostate cancer on the basis of the CT finding of focal abnormally increased peripheral enhancement in the prostate. Binary classification of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) was used to assess the diagnostic utility of CT versus the reference standard of transrectal ultrasound-guided biopsy. RESULTS. Eighty-three of 100 patients with biopsy-proven prostate cancer and 92 of 100 control subjects were correctly identified (sensitivity, 0.83; specificity, 0.92; PPV, 0.91; NPV, 0.84). There was no significant difference in diagnostic accuracy among subjects with different Gleason scores. Interrater agreement on both the cancer and control patients was 0.76 as assessed by Cohen kappa statistic. CONCLUSION. Incidental detection of a focal area of increased enhancement in the periphery of the prostate at contrast-enhanced CT may represent a clinically significant cancer and deserves further workup with prostate-specific antigen measurement and correlation with clinical risk factors for prostate cancer.