To analyze the value of ⁶⁸Ga-Prostate-specific membrane antigen (PSMA)-11 PET/CT delayed imaging in the detection of pelvic recurrence after radical prostatectomy.

Twenty-four patients who underwent radical prostatectomy at our institution were retrospectively enrolled in the study. The patients received ⁶⁸Ga-PSMA-11 PET/CT whole-body standard imaging at 60 min and pelvic delayed imaging at 180 min after intravenous injection of radiopharmaceutical. The number, size, maximum standard uptake (SUV_max) and target-to-background ratio (T/B) of pelvic recurrent lesions were compared between standard imaging and delayed imaging.

Pelvic recurrence occurred in 17 of the 24 patients. Of the recurrent patients, standard imaging was positive in 15 cases and delayed imaging was positive in 17 cases. There were 7 cases without recurrence, and both standard imaging and delayed imaging were negative. There was no statistical difference (χ²=2.125, P=0.145) in the sensitivity of detecting pelvic recurrence between standard imaging (82.24%, 15/17) and delayed imaging (100.00%, 17/17). Delayed imaging detected 10 more pelvic positive lesions than standard imaging. The diameter 4(3, 8) mm of additional pelvic lesion detected by delayed imaging was smaller than that 8(7, 12) mm of pelvic lesion detected by standard imaging (U=94, P=0.004). The SUV_max 10.08(6.58, 15.50) of delayed imaging was similar to that of standard imaging 7.89(4.87, 15.26) (U=1204, P=0.234), however the T/B value of delayed imaging 55.90(30.45, 109.27) was significantly higher than that of standard imaging 32.89(21.67, 55.07) (U=840, P=0.0005).

⁶⁸Ga-PSMA-11 PET/CT delayed imaging can detect more and smaller pelvic recurrent lesions after radical prostatectomy.