68Ga-PSMA-11 PET/CT in patients with occult biochemical recurrence of prostate carcinoma and negative 18F-Choline PET/CT. Preliminary assessment of its clinical use

Abstract

ObjectiveTo assess the clinical usefulness of 68Ga-PSMA PET/CT studies in patients with occult biochemical recurrence of prostate carcinoma, with negative or inconclusive radiologic and 18 F-Choline PET/CT imaging studies. Material and methodsRetrospective descriptive study. The first 14 patients with a history of prostate carcinoma, treated with curative intent and presenting suspicion of biochemical recurrence with low PSA values (<3 ng/mL) were selected. Imaging studies, prostate ultrasound, pelvic CT and/or MRI were negative, and all of them had a negative or inconclusive 18F-Choline PET/CT.All patients were referred to 68 Ga-PSMA-11 PET/CT. Protocol: Dose 2.2 M Bq/kg. 20 mg furosemide at start. PET/CT images from skull base to proximal third of thighs at 60 min, and late images at 3 h if needed. ResultsThe 68 Ga-PSMA-11 PET/CT was able to localize the occult biochemical recurrence in 9 of the 14 patients (64.2%), and it affected the therapeutic attitude in all of them.Four patients (28.5%) obtained a negative or inconclusive 68 Ga-PSMA-11 PET/CT and continued under vigilant approach with PSA controls and imaging studies according to the clinical guidelines. These patients had the lowest PSA values (less than 1 ng/mL).One of the 68 Ga-PSMA-11 PET/CT studies was inconclusive, reporting the presence of a doubtful right iliac adenopathy. Conclusion68 Ga-PSMA-11 PET/CT allows an early diagnosis, with low PSA values, of occult biochemical recurrence of prostate carcinoma, even in patients with negative 18 F-Choline PET/CT.