Table 1.

List of PET ligands available for 5-HTR imaging in human.

Receptor subtype	PET Ligands	Advantages	Limitations
5-HT1AR antagonist	[Carbonyl-11C]WAY-100635	High target to non-target ratio	Complex radiosynthesis, fast metabolism, difficulty of quantification with arterial input functions.
	[11C]cis-FCWAY		Radiodefluorination
	[11C]MPPF		P-gp substrate, low target to non target ratio
	[11C]trans-MeFWAY	High target to non-target ratio	Quantification with arterial input data is currently not available
5-HT1AR partial agonist	[11C]CUMI-101	Binding to high affinity site in human and NHP	Partial agonist, a-1AR cross selectivity is reported in rodents and monkey.
5-HT1BR antagonist	[11C]AZ10419369
	[11C]P943	Reported altered binding in a variety of pathological conditions
5-HT2AR antagonist	[18F]Altanserin		Interference of radiometabolite in quantification, need bolus infusion paradigm for injection.
	[18F]Setoperone		Nonselective for D2R
	[11C]NMSP		Cross affinity for D2, a-1R, 5-HT1AR, and 5-HT2CR
	[11C](R)-M100907		Slow kinetics
5-HT2AR agonist	[11C]CIMBI-36
5-HT4R antagonist	[11C]SB207145		Not sensitive to endogenous 5-HT changes, Altered binding in 5-HTTLPR
5-HT6R antagonist	[11C]GSK215083		Cross selectivity to 5-HT2AR