Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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Purpose: The aim of this study was to assess a) the impact of forced diuresis with early furosemide injection on the detection rate of local recurrence (LR) in prostate cancer (PC) patients with biochemical recurrence (BR) referred for 68Ga-labelled Glu-NH-CO-NH-Lys(Ahx)-HBED-CC (68Ga-PSMA-11) Positron Emission Tomography/Computed Tomography (PET/CT) and b) whether intravenous administration of furosemide shortly after tracer injection increases renal wash-out of 68Ga-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. Materials and Methods: In a retrospective analysis two different groups with 220 prostate cancer patients each, referred for 68Ga-PSMA-11 PET/CT because of biochemical recurrence after primary therapy, were compared: patients of group one (median prostate specific antigen (PSA): 1.30 ng/ml) receiving no preparation prior to imaging, whereas patients in group two (median PSA: 0.82 ng/ml) were injected with 20 mg furosemide and 500 ml sodium chloride (NaCl 0.9%) immediately after tracer injection. Presence of local recurrence was assessed visually. ⋯ Apart from bladder activity, no significant reduction of tracer accumulation was found in the patient group receiving furosemide. Conclusion: Injection of 20 mg furosemide at the timepoint of radiotracer administration significantly increases the detection rate of local recurrence in prostate cancer patients with biochemical recurrence referred for 68Ga-PSMA-11 PET/CT. As intensity of 68Ga-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 68Ga-PSMA-11 seems unlikely.
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Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin receptor (SSTR) analogs is a common approach in advanced neuroendocrine neoplasms. Recently, SSTR antagonists have shown promising results for imaging and therapy due to a higher number of binding sites than in commonly used agonists. We evaluated PRRT with SSTR agonist 177Lu-DOTATOC and antagonist 177Lu-DOTA-JR11 longitudinally in an orthotopic murine pancreatic neuroendocrine neoplasm model expressing human SSTR2. ⋯ These results were confirmed by 18F-FDG PET, revealing the least amount of viable tumor tissue in 177Lu-DOTA-JR11-treated animals, at 6.2% (IQR, 2%-23%). Conclusion: 177Lu-DOTA-JR11 showed a higher tumor-to-kidney ratio and a more pronounced cytotoxic effect than did 177Lu-DOTATOC. Additionally, tumor uptake was more stable over the course of 2 treatment cycles.