To investigate the diagnostic value of MRI for persistent prostate cancer after IRE therapy

In this multi-center randomized trial, men with localized low-intermediate risk prostate cancer were randomized to receive either focal or extended IRE ablation. All the patients underwent repeat MRI scans at 6 and 12 months and transperineal template mapping biopsy (TMB) at 6 months post-IRE, Outcome measurements and statistical analysis: Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of MRI were calculated for infield and outfield lesions by 2×2 contingency tables with 95% confidence intervals (CIs) for clinically significant prostate cancer and any grade prostate cancer.

A total of 106 patients were recruited in this study, including 39 (36.8%) cases of clinically insignificant prostate cancer and 67 (63.2%) cases of clinically significant prostate cancer (ISUP≥2). 101 patients underwent repeat MRI scan and prostate biopsy at 6 months after IRE. The clinically significant prostate cancer detected by TMB infield and outfield was 9.9% (10/101) and 9.9% (10/101). In the treated area, the sensitivity, specificity, PPV, and NPV for MRI to detect clinically significant prostate cancer were 30.0% (95% CI: 6.7%-65.2%), 90.6% (95% CI: 82.3%-95.8%), 27.3% (95% CI: 6.0%-61.0%), 91.7% (95% CI: 83.6%-96.6%), respectively. In the untreated area, the sensitivity, specificity, PPV, and NPV of MRI were 20.0% (95% CI: 2.5%-55.6%), 90.6% (95% CI: 82.3%-95.8%), 20.0% (95% CI: 2.5%-55.6%), 90.6% (95% CI: 82.3%-95.8%) for clinically significant prostate cancer.

MRI achieved favorable specificity but poor sensitivity in detecting persistent clinically significant prostate cancer after IRE treatment. The repeat template mapping biopsy should not be deferred, regardless of MRI results.