Comparison of clinical performance between late and standard total-body [ Ga]Ga-PSMA-11 in biochemical recurrent prostate cancer.

Background And Purpose: Enhanced lesion detection in prostate cancer is observed with late [ Ga]Ga-PSMA-11 PET/CT imaging compared to standard [ Ga]Ga-PSMA-11 PET/CT imaging (50-100 min p.i.). However, the poor image quality of late imaging using short axial field of view (SAFOV) PET/CT has hindered its sole clinical adoption. Conversely, the image quality of late imaging with a long axial field of view (LAFOV) [ Ga]Ga-PSMA-11 PET/CT fulfills clinical diagnostic requirements. Nonetheless, the diagnostic efficacy of late LAFOV [ Ga]Ga-PSMA-11 PET/CT with forced diuresis and its impact on treatment decisions, compared to standard LAFOV [ Ga]Ga-PSMA-11 PET/CT, remains unclear. This study aims to compare the rate of PET positivity between late and standard LAFOV [ Ga]Ga-PSMA-11 PET/CT and to evaluate the influence of late LAFOV [ Ga]Ga-PSMA-11 PET/CT with forced diuresis on treatment decisions relative to standard scans.

Methods: From January 2021 to April 2024, 127 patients with biochemical recurrence of prostate cancer post-radical prostatectomy were enrolled to undergo both standard and late LAFOV [ Ga]Ga-PSMA-11 PET/CT scans at Shanghai Renji Hospital. We compared the rate of PET positivity between the two modalities at the patient level and across different anatomical regions. We assessed the added diagnostic value of late LAFOV [ Ga]Ga-PSMA-11 PET/CT and its impact on modifying patient treatment plans.

Results: The image quality of late LAFOV [ Ga]Ga-PSMA-11 PET/CT with forced diuresis in all patients met clinical diagnostic requirements. The rate of PET positivity of late LAFOV [ Ga]Ga-PSMA-11 PET/CT with forced diuresis were significantly higher than those of standard LAFOV [ Ga]Ga-PSMA-11 PET/CT (80.31% [102/127] vs. 65.35% [83/127]; P < 0.001). Late LAFOV [ Ga]Ga-PSMA-11 PET/CT demonstrated higher lesion SUVmax (16.69 ± 16.42 vs. 11.91 ± 10.72, P < 0.001) and TBR (6.26 ± 7.21 vs. 3.44 ± 3.57, P < 0.001) compared to standard LAFOV scans. Additionally, 14.17% (18/127) of patients experienced changes in their treatment regimen due to the superior detection capabilities of late LAFOV [ Ga]Ga-PSMA-11 PET/CT with forced diuresis compared to the standard scan.

Conclusions: The rate of PET positivity of late LAFOV [ Ga]Ga-PSMA-11 PET/CT with forced diuresis compared to standard LAFOV [ Ga]Ga-PSMA-11 PET/CT highlight its potential as a valuable diagnostic tool for biochemically recurrent prostate cancer. This study paves the way for using late LAFOV [ Ga]Ga-PSMA-11 PET/CT with forced diuresis for prostate cancer imaging in daily clinical practice, facilitating more accurate and timely diagnoses.