TABLE 1

Clinically Used Radiolabeled Catecholamine Analogs

Tracer	Uptake-1 affinity	Vesicular storage	MAO/COMT-sensitive	General characteristics
¹²³I-MIBG	++	+	–	Catecholamine analog; distributes in cytoplasm and vesicles after neuronal uptake
¹¹C-HED	++	O	–	Catecholamine analog; undergoes constant uptake and reuptake by NET
¹¹C-EPI	+	++	+	Physiologic neurotransmitter; requires vesicular storage for protection from degradation
¹¹C-PHEN	+	+	+	Catecholamine analog; washout reflects vesicular leakage and MAO activity
¹⁸F-FDA	+	++	+	Precursor of physiologic neurotransmitter; requires enzymatic conversion and vesicular storage for protection from degradation
¹⁸F-LMI1195	?	?	?	Guanidine analog in phase 1 and 2 clinical studies; published information is limited

COMT = catecholamine-O-methyl-transferase; HED = hydroxyephedrine; NET = norepinephrine transporter; EPI = epinephrine; PHEN = phenylephrine; FDA = fluorodopamine.