Abstract
IntroductionPositron emission tomography (PET) using small ligands of the fibroblast activation protein (FAP) was recently introduced. However, optimal uptake time has not been defined yet. Here, we systematically compare early (~ 10 min p.i.) and late (~ 60 min p.i.) FAPI-46 imaging in patients with various types of cancer.MethodsThis is a retrospective single-institutional study. Imaging was performed at the Essen University Hospital, Germany. A total of 69 patients who underwent dual time-point imaging for either restaging (n = 52, 75%) or staging (n = 17, 25%) of cancer were included. Patients underwent PET with two acquisitions: early (mean 11 min, SD 4) and late (mean 66 min, SD 9). Mean injected activity was 148 MBq (SD 33).ResultsIn total, 400 lesions were detected in 69 patients. Two of 400 (0.5%) lesions were only seen in early time-point imaging but not in late time-point imaging. On a per-patient level, there was no significant difference between SUVmax of hottest tumor lesions (Wilcoxon: P = 0.73). Organ uptake demonstrated significant early to late decrease in SUVmean (average ∆SUVmean: − 0.48, − 0.14, − 0.27 for gluteus, liver, and mediastinum, respectively; Wilcoxon: P < 0.001). On a per-lesion basis, a slight increase of SUVmax was observed (average ∆SUVmax: + 0.4, Wilcoxon: P = 0.03).ConclusionIn conclusion, early (~ 10 min p.i.) versus late (~ 60 min p.i.) FAPI-46 imaging resulted in equivalent lesion uptake and tumor detection. For improved feasibility and scan volume, we implement early FAPI-46 PET in future clinical and research protocols.
Highlights
Positron emission tomography (PET) using small ligands of the fibroblast activation protein (FAP) was recently introduced
FAPI-46 exhibited high tumor-tobackground uptake ratios enabling oncologic imaging as well as theranostic applications [1]
Dosimetry and biodistribution of [68Ga]Ga-FAPI-46 were reported recently in six patients showing high tumor-tobackground uptake along with a low equivalent dose of approximately 5.3 mSv for combined 200 MBq [68Ga]Ga-FAPI-46 PET with low-dose CT scan. [7]
Summary
Positron emission tomography (PET) using small ligands of the fibroblast activation protein (FAP) was recently introduced. We systematically compare early (~ 10 min p.i.) and late (~ 60 min p.i.) FAPI-46 imaging in patients with various types of cancer. FAPI-46 exhibited high tumor-tobackground uptake ratios enabling oncologic imaging as well as theranostic applications [1]. Dosimetry and biodistribution of [68Ga]Ga-FAPI-46 were reported recently in six patients showing high tumor-tobackground uptake along with a low equivalent dose of approximately 5.3 mSv for combined 200 MBq [68Ga]Ga-FAPI-46 PET with low-dose CT scan. We systematically compare biodistribution and detection rate between early (~ 10 min p.i.) and late (~ 60 min p.i.) FAPI-46 PET in patients with various types of cancer.
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More From: European Journal of Nuclear Medicine and Molecular Imaging
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