Gross tumor volume delineation in primary prostate cancer on 18F-PSMA-1007 PET/MRI and 68Ga-PSMA-11 PET/MRI

Abstract Background We aimed to assess the clinical value of 18F-PSMA-1007 and 68Ga-PSMA-11 PET/MRI in the gross tumor volume (GTV) delineation of radiotherapy for prostate cancer (PCa). Methods Sixty-nine patients were retrospectively enrolled (57 in the 18F subgroup and 12 in the 68Ga subgroup). Three physicians delineated the GTV and tumor length by the visual method and threshold method with thresholds of 30%, 40%, 50%, and 60% SUVmax. The volume correlation and differences in GTVs were assessed. The dice similarity coefficient (DSC) was applied to estimate the spatial overlap between GTVs. For 51 patients undergoing radical prostatectomy, the tumor length (Lpath) of the maximum area was measured, and compared with the longest tumor length obtained based on the images (LMRI, LPET/MRI, LPET, LPET30%, LPET40%, LPET50%, LPET60%) to determine the best delineation method. Results In the 18F subgroup, (1) GTV-PET/MRI (p 0.7. (2) GTV-MRI (R 2 = 0.462, p 0.7. (2) There was a significant correlation between GTV-MRI (r = 0.580, p