Head-to-head comparison of GA-68 PSMA PET/CT and multiparametric MRI findings with postoperative results in preoperative locoregional staging and localization of prostate cancer.

Background: Accurate staging of prostate cancer (PCa) is essential for determining the appropriate treatment and predicting outcomes. This study is comparing the effectiveness of Gallium-68 Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography (Ga-68 PSMA PET/CT) and multiparametric MRI (mpMRI) in preoperative locoregional staging and localizing PCa.

Methods: A retrospective analysis was conducted on 78 patients who underwent both mpMRI and Ga-68 PSMA PET/CT scans before surgery. The imaging was reviewed by radiologists and nuclear medicine specialists and compared with the final histopathology, which was reviewed by an experienced uropathologist.

Results: mpMRI demonstrated higher sensitivity in detecting extraprostatic extension (EPE) and bladder neck invasion (BNI) compared to Ga-68 PSMA PET/CT (83% vs. 44% and 29% vs. 17%, respectively). Conversely, Ga-68 PSMA PET/CT showed higher sensitivity in detecting seminal vesicle invasion (SVI) and lymph node metastasis (LNM) (75% vs. 55% and 50% vs. 30%, respectively). When both methods were combined, sensitivity increased in detecting both EPE and SVI. The index tumor localization in mpMRI and Ga-68 PSMA PET/CT was found to be in complete agreement with histopathological findings at 36.4% and 41.8%, respectively. When both imaging methods were combined, the agreement with histopathology in predicting index tumor localization reached 72.1%.

Conclusion: Both mpMRI and Ga-68 PSMA PET/CT provide valuable and complementary information for tumor localization and locoregional staging. While mpMRI showed higher sensitivity in detecting EPE, Ga-68 PSMA PET/CT demonstrated superior performance in detecting LNM and SVI. The combined use of these imaging modalities enhance accuracy of index tumor localizations.