68Ga-PSMA I&T PET/CT for assessment of prostate cancer: evaluation of image quality after forced diuresis and delayed imaging

Urinary radiotracer excretion of Ga-68-Labelled prostate-specific membrane antigen (PSMA) ligands may complicate the assessment of the prostate region and differentiation of lymph nodes from ureteral activity. The aim of this study was to assess the value of delayed imaging after forced diuresis. Sixty-six patients underwent Ga-68-PSMA I&T PET/CT for evaluation of prostate cancer at 60 min post-injection. In subgroups of patients, this was amended by delayed imaging after 180 min post-injection, preceded by furosemide and oral hydration early, at the time of tracer injection, or delayed, at 100 min post-injection. Urinary tracer activity within the bladder and focal ureteral activity was analyzed. After forced diuresis, linear and focal visualization of ureters was significantly reduced. After delayed furosemide, mean and peak bladder activity decreased (p < 0.001), and image quality of the prostate region improved on delayed images (p < 0.001). Early furosemide co-injection with tracer resulted in increased mean and peak bladder activity (p < 0.001) and in deteriorated image quality of the prostate region on delayed images (p = 0.008). Ga-PSMA I&T PET/CT delayed imaging after forced diuresis can improve the assessment of prostate region and pelvic lymph nodes by removing excreted tracer from the lower urinary tract. aEuro cent Forced diuresis can improve image quality in (68) Ga-PSMA I&T. aEuro cent After forced diuresis, linear and focal visualization of ureters was reduced. aEuro cent Timing of diuresis relative to (68) Ga-PSMA I&T injection is important. aEuro cent Early furosemide co-injection with tracer resulted in deteriorated image quality on delayed images. aEuro cent After delayed furosemide, image quality improved on delayed images.