Abstract
1461
Aim: Given the increasing interest for 68Ga-PSMA-11 PET/MR as a staging tool for patients with prostate cancer (PCA), knowledge about normal intraprostatic distribution of 68Ga-PSMA-11 is essential. It was the aim of this study to investigate the physiologic interzonal 68Ga-PSMA-11 distribution in the prostatic gland. MATERIALS AND METHODS:All patients that underwent 68Ga-PSMA-11 PET/MR between June 2016 and May 2017 for high risk PCA, prior to radical prostatectomy were retrospectively analyzed. For each patient, standardized ROIs were placed bilaterally in central (CZ), transition (TZ) and peripheral zones (PZ), according to T2-FRFSE MR sequences either in axial or coronal planes. ROIs were placed only in healthy tissue, without spill-over from PCA. SUVmax and SUVmean were determined and their differences among the regions were assessed with Wilcoxon signed-ranks test. P-values <0.05 were considered significant. RESULTS: Eighteen patients were analyzed. A total of 65 ROIs were placed; 22 in central zone, 22 in transition and 21 in peripheral zone. Differences of SUVmax between central (mean 3.8±0.58) and transitional (mean 3.3±0.57) as well as between central and peripheral (mean 2.8±0.57) zones were statistically significant (p=0.005, p=0.001, respectively). In addition, differences for SUVmean between CZ and PZ were found to be statistically significant (p=0.001). CONCLUSION: Our data suggest that a higher 68Ga-PSMA-11 accumulation in the central zone, compared to the transition or peripheral zone is normal, leading to a "Mickey Mouse ears" shape on 68Ga-PSMA-11-PET. This pattern could be helpful to avoid false positive interpretation of PET scans.