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EJNMMI Res. 2017 Oct 16;7(1):84. doi: 10.1186/s13550-017-0334-8.

Comparison of four 11C-labeled PET ligands to quantify translocator protein 18 kDa (TSPO) in human brain: (R)-PK11195, PBR28, DPA-713, and ER176-based on recent publications that measured specific-to-non-displaceable ratios.

Author information

1
Molecular Imaging Branch, National Institute of Mental Health, Bldg. 10, Rm. B1D43, 10 Center Drive, MSC-1026, Bethesda, MD, 20892-1026, USA. fujitam@mail.nih.gov.
2
Molecular Imaging Branch, National Institute of Mental Health, Bldg. 10, Rm. B1D43, 10 Center Drive, MSC-1026, Bethesda, MD, 20892-1026, USA.
3
Imanova Ltd, London, UK.
4
Division of Brain Sciences, Department of Medicine, Imperial College, London, UK.
5
Centre for Neuroimaging Sciences, Institute of Psychiatry, Psychology and Neuroscience, King's College, London, UK.

Abstract

Translocator protein (TSPO) is a biomarker for detecting neuroinflammation by PET. 11C-(R)-PK11195 has been used to image TSPO since the 1980s. Here, we compared the utility of four 11C-labeled ligands-(R)-PK11195, PBR28, DPA-713, and ER176-to quantify TSPO in healthy humans. For all of these ligands, BP ND (specific-to-non-displaceable ratio of distribution volumes) was measured by partially blocking specific binding with XNBD173 administration. In high-affinity binders, DPA-713 showed the highest BP ND of 7.3 followed by ER176 (4.2), PBR28 (1.2), and PK11195 (0.8). Only ER176 allows the inclusion of low-affinity binders because of little influence of radiometabolites and high BP ND. If inclusion of all three genotypes is important for study logistics, ER176 is the best of these four radioligands for studying neuroinflammation.

KEYWORDS:

BP ND; Neuroinflammation; Radiometabolites; Single nucleotide polymorphism; Specific-to-non-displaceable ratio

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