Table 1. Published PET tracers for visualizing transplanted islets.

Method for labeling	Tracer	References	Radioactivity	Islet donor species	Comments
Labeling of islets directly	[18F]FDG	17 , 33	4–6 h	human, rat	Available for clinical use already Short radioactivity High uncharacteristic washout
	[18F]FHBG	18 - 20	1–3 mo	human, rat, mouse	Longer radioactivity Use of viral vector
Labeling of islets via intravenous infusion	[11C]DTBZ	23	Approximately 30 min	rat	Specific labeling of islets via VMAT2 Short radioactivity
	[64Cu]/[18F]-labeled exendin-4	26 , 36	Over 4 h	human	Specific labeling of islets via GLP-1 receptor
	[18F]- labeled fallypride	30	Over 1.5 h	rat	Specific labeling of islets via D2/D3 receptor Available for clinical use already Binds to other organs (mainly the brain)
	[68Ga]-labeled biotin	32	Over 30 min	human	Specific labeling of islets via avidin-biotin interaction Prevention of IBMIR