Objective: To evaluate the effectiveness of 3 Tesla endorectal magnetic resonance imaging (erMRI) with fusion to real-time transrectal ultrasound to detect a dominant cancer focus within the prostate gland. Materials and Methods: The safety and effectiveness of identifying suspicious lesions using erMRI was assessed in men undergoing brachytherapy perineal implants. Suspicious lesions identified on erMRI fused to real-time transrectal ultrasound were biopsied at brachytherapy seed placement. In addition, a biopsy was also obtained from an area identified as negative for cancer. This prospective study was performed for 30 patients who had previously provided consent for brachytherapy. Eligible patients had to have a lesion on erMRI that was ≥1.0 cm × 1.0 cm. Their mean prostate-specific antigen level was 7.3 ng/mL, mean Gleason score 6.75, and mean percentage of positive diagnostic core biopsies was 29%. Results: Cancer was detected in a suspicious area in 53% of the patients. In 9 of these patients, the cancer was Gleason score 3 + 3, in 6, Gleason score 3 + 4, and in 1, Gleason score 4 + 3. Cancer was detected in unsuspected areas in 10% of patients; all Gleason score 3 + 3 in <10% of the core. No adverse events from the biopsy were reported. Conclusion: Although biopsy of lesions identified by erMRI is safe and more effective than would be expected by blind biopsy, a significant "miss" rate was still found. However, the negative predictive (10%) value of this technique might be useful for determining which regions of the gland might not need treatment in the setting of focal therapy.
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