The superior detection rate of total-body [68Ga]Ga-PSMA-11 PET/CT compared to short axial field-of-view [68Ga]Ga-PSMA-11 PET/CT for early recurrent prostate cancer patients with PSA < 0.2 ng/mL after radical prostatectomy

Background and purpose [Ga-68]Ga-PSMA PET imaging has been extensively utilized for the detection of biochemical recurrence (BCR) in prostate cancer. However, the detection rate declines to merely 10-40% when PSA levels are < 0.2 ng/mL employing short axial field-of-view (SAFOV) PET. Prior studies exhibited superior detection rates with total-body [Ga-68]Ga-PSMA-11 PET compared to SAFOV [Ga-68]Ga-PSMA-11 PET in BCR patients with PSA > 0.2 ng/mL. Nevertheless, the diagnostic utility of total-body [Ga-68]Ga-PSMA-11 PET for BCR patients when PSA is < 0.2 ng/mL remains unclear. This study aimed to assess whether total-body [Ga-68]Ga-PSMA-11 PET/CT could improve the detection rate compared to SAFOV [Ga-68]Ga-PSMA-11 PET/CT in BCR patients with PSA < 0.2 ng/mL. Methods Eighty BCR patients with PSA < 0.2 ng/mL underwent total-body [Ga-68]Ga-PSMA-11 PET/CT. These patients were matched by baseline qualities to another 80 patients who received SAFOV [Ga-68]Ga-PSMA-11 PET/CT. The detection rates of total-body [Ga-68]Ga-PSMA-11 PET/CT and SAFOV [Ga-68]Ga-PSMA-11 PET/CT were compared utilizing a chi-square test and stratified analysis. Image quality of total-body [Ga-68]Ga-PSMA PET/CT and SAFOV [Ga-68]Ga-PSMA-11 PET/CT was assessed based on subjective scoring and objective parameters. The objective parameters measured were SUVmax, SUVmean, standard deviation (SD) of SUV, and signal-to-noise ratio (SNR) of liver and gluteus maximus. Results The image quality of total-body [Ga-68]Ga-PSMA PET/CT was superior to that of SAFOV [Ga-68]Ga-PSMA-11 PET/CT in both early and delayed scans. The detection rate of total-body [Ga-68]Ga-PSMA PET/CT for BCR patients with PSA < 0.2 ng/mL was significantly higher than that of SAFOV [Ga-68]Ga-PSMA-11 PET/CT (73.75% vs. 43.75%, P < 0.001). Total-body [Ga-68]Ga-PSMA PET/CT resulted in noteworthy modifications to the treatment regimen when contrasted with SAFOV [Ga-68]Ga-PSMA-11 PET/CT. Conclusions In BCR patients with PSA < 0.2 ng/mL, total-body [Ga-68]Ga-PSMA-11 PET/CT not only demonstrated a significantly higher detection rate compared to SAFOV [Ga-68]Ga-PSMA-11 PET/CT but also led to significant alterations in treatment regimens.