Early Injection of Furosemide Increases Detection Rate of Local Recurrence in Prostate Cancer Patients with Biochemical Recurrence Referred for 68 Ga-PSMA-11 PET/CT.

The aim of this study was twofold. First, we aimed to assess the impact of forced diuresis with early furosemide injection on the detection rate of local recurrence in prostate cancer patients with biochemical recurrence referred for ⁶⁸ Ga-labeled Glu-NH-CO-NH-Lys(Ahx)-HBED-CC ( ⁶⁸ Ga-PSMA-11) PET/CT. Second, we determined whether intravenous administration of furosemide shortly after tracer injection increases renal washout of ⁶⁸ Ga-PSMA-11 before it binds to the PSMA receptor with possible influence on biodistribution and intensity of tracer uptake in organs with physiologic tracer accumulation. Methods: In a retrospective analysis, 2 different groups with 220 prostate cancer patients each, referred for ⁶⁸ Ga-PSMA-11 PET/CT because of biochemical recurrence after primary therapy, were compared: patients in group 1 (median prostate-specific antigen, 1.30 ng/mL) received no preparation before imaging, whereas patients in group 2 (median prostate-specific antigen, 0.82 ng/mL) were injected with 20 mg of furosemide and 500 mL of sodium chloride (NaCl 0.9%) immediately after tracer injection. The presence of local recurrence was assessed visually. In addition, the intensity of tracer accumulation in organs with physiologic tracer uptake was evaluated. Results: The detection rate of lesions judged positive for local recurrence was significantly higher in patients receiving furosemide than in patients without preparation: 56 cases (25.5%) versus 38 cases (17.3%), respectively ( P = 0.048). Median maximum SUVs (SUV _max ) of organs with physiologic uptake of ⁶⁸ Ga-PSMA-11 in groups 1 and 2 were urinary bladder (63.0 vs. 8.9), kidney (55.6 vs. 54.5), liver (9.9 vs. 9.4), spleen (11.2 vs. 11.9), small bowel (16.2 vs. 17.1), parotid gland (19.2 vs. 19.6), lacrimal gland (8.9 vs. 10.9), blood-pool activity (2.2 vs. 2.3), muscle (1.0 vs. 1.1), and bone (1.6 vs. 1.6). Apart from bladder activity, no significant reduction of tracer accumulation was found in the patient group receiving furosemide. Conclusion: Injection of 20 mg of furosemide at the time point of radiotracer administration significantly increases the detection rate of local recurrence in prostate cancer patients with biochemical recurrence referred for ⁶⁸ Ga-PSMA-11 PET/CT. As intensity of ⁶⁸ Ga-PSMA-11 uptake in organs with physiologic uptake is not significantly reduced, a negative impact of early furosemide injection on targeting properties and biodistribution of ⁶⁸ Ga-PSMA-11 seems unlikely.
(© 2021 by the Society of Nuclear Medicine and Molecular Imaging.)