Table 2.

Pet tracers of neuroinflammation.

Tracer and Radioisotope	Target	Tested in	Notes	References
[11C]-(R)-PK11195	TSPO	human ALS patients and healthy controls	signals are not influenced by patient’s TSPO genotype	[103,131]
		rat model of cerebral ischemia (Wistar rats)	poor specificity
[18F]DPA-714	TSPO	ALS model (SOD1G93A mouse)	signals correlate to increased TSPO expression and compromised brain regions	[87,131]
		rat model of cerebral ischemia (Wistar rats)	higher affinity and better signal-to-noise ratio than PK11195
[11C]-PBR28	TSPO	human ALS, PLS patients and healthy controls	signals correlate to glial activation and inflammation	[102,132]
		human healthy subjects	binding is affected by TSPO polymorphism
[11C]A-836339	CB2	neuroinflammation-induced/AD models (CD-1 and APPswe/PS1ΔE9 mouse)	first CB2 radiotracer tested	[123,124]
		AD model (APPswe/PS1ΔE9 mouse)	detection of neuroinflammation very early in the pathology
[11C]NE40	CB2	AD, PD patients and healthy controls	no differences between disease and control cases	[127,128,133]
		ischemic stroke model (Sprague–Dawley rat)	signal in peri-infarct area, concomitant to CB2 up-regulation
		senescence-accelerated model (SAMP10 mouse)	detection of early signs of neuroinflammation in cortex
[11C]KD2	CB2	ALS patients	selective binding in post-mortem ALS spinal cord specimens	[129,134]
		neuroinflammation-induced model (CD-1 mouse)	limited target specificity and excessive lipophilicity
[11C]RS-016	CB2	neuroinflammation-induced model (CD-1 mouse)	high blood stability and CB2 specificity	[134]
		ALS patients	selective binding in post-mortem ALS spinal cord specimens
[18F]29	CB2	neuroinflammation-induced model (CD-1 mouse)	CB2 specific tracing but very rapid metabolism	[105]
[18F]3	CB2	Wistar rats	rapid washout from brain tissue	[130]
		ALS patients and healthy controls	selective binding in post-mortem ALS spinal cord specimens
[11C]GSK1482160	P2X7	neuroinflammation-induced model (C57BL6)	increased signals in CNS sites with prominent neuroinflammation	[135]