Recent Advances in Imaging of Dopaminergic Neurons for Evaluation of Neuropsychiatric Disorders

Table 1

Radiotracers available for targeting different steps in the process of dopaminergic neurotransmission and clinical applications.

Targeting	Tracer	Chemical name	Clinical studies (references)
Dopamine synthesis and turn over	^18F-DOPA	L-3,4-dihydroxy-6-[^18F]-fluorophenylalanine	PD [11, 20–23], gene therapy for PD [24–26], ADHD [27], schizophrenia [28, 29]
	^18F-FMT	O-[^18F]-fluoromethyl-D-tyrosine	Gene therapy for PD [30, 31]
Dopamine transporter	^11C-CFT	[^11C]-2β-carbomethoxy-3β-ltropane	Heroin abuse [32]
	^11C-altropane	2β-carbomethoxy-3β-(4-fluorophenyl)-N-((E)-3-iodo-prop-2-enyl)tropane	ADHD [33]
	^123I-β-CIT (Dopascan)	[^123I]-(1R)-2-β-carbomethoxy-3-β-(4-iodophenyl)-tropane	PD [11, 20], PM [34], PD & ET [35], cocaine abuse [36, 37], ADHD [38]
	^123I-FP-CIT (DaTSCAN)	[^123I] N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane	PM [39–41], PM & ET [42], PD & DLB [43], AD, PD & DLB [44], ADHD [45–47], schizophrenia [48]
	^99mTc-TRODAT-1	[^99mTc]technetium [2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo [3.2.1]oct-2-yl]-methyl](2-mercaptoethyl)amino]-ethyl]amino]ethane-thiolato(3-)-N2,N2′,S2,S2′]oxo-[1R-(exo-exo)]	PD [23, 49–51], MSA [52], PM & VP [53], DRD [54], PSP [55], genetic study of PD [51, 56], genetic study of MJD [57], cocaine abuse [58], opiate abuse [59], nicotine dependence [60, 61], ADHD [62–68]
	^123I-altropane	[^123I]-2β-carbomethoxy-3β-(4-fluorophenyl)-N-(1-iodoprop-1-en-3-yl) ortropane	PD [21], ADHD [69]
	^123I-IPT	[^123I]-N-(3-iodopropen-2-yl)-2-carbomethoxy-3beta-(4-chlorophenyl) tropane	ADHD [70]
Dopamine D1 receptor	^11C-NNC 112	(+)-5-(7-Benzofuranyl)-8-chloro-7-hydroxy-3-methyl-2,3,4,5-tetrahydro-1H-3-benzazepine	Schizophrenia [71]
	^11C-SCH 23390	(R)-(+)-8-Chloro-2,3,4,5-tetrahydro-3-[^11C]methyl-5-phenyl-1H-3-benzazepin-7-ol	Schizophrenia [72, 73]
Dopamine D2 receptor	^11C-Raclopride	3,5-dichloro-N-{[(2S)-1-ethylpyrrolidin-2-yl]methyl}-2-hydroxy-6-[^11C]methoxybenzamide	Drug abuse [74–79] cocaine abuse [80, 81], methamphetamine abuse [82], opiate abuse [83], alcohol dependence [84], ADHD [85, 86], antipsychotics [48, 87–89]
	^123I-IBZM	(S)-(-)-3-[^123I]iodo-2-hydroxy-6-methoxy-N-[(1-ethyl-2-pyrrolidinyl)methyl]benzamide	PM [40, 41], schizophrenia [90], antipsychotics [89, 91, 92]
vesicular monoamine transporter type-2	^11C-DTBZ	(±)-α-[^11C]dihydrotetrabenazine	PD [7, 11, 20]
	^18F-FP-DTBZ (AV-133)	9-[^18F]fluoropropyl-(+)-dihydrotetrabenazine	PD [93], DLB & AD [94]

Abbreviations: Parkinson’s disease (PD), Parkinsonism (PM), multiple-system atrophy (MSA), progressive supranuclear palsy (PSP), essential tremor (ET), vascular Parkinsonism (VP), Machado-Joseph disease (MJD), DOPA-responsive dystonia (DRD), dementia with Lewy bodies disease (DLB), Alzheimer’s disease (AD), and attention deficit hyperactivity disorder (ADHD).