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Table 1 Distribution volume and the time stability of four 11C–radioligands to image translocator protein (TSPO)

From: 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

  V T BP ND Time stabilitya of V T
Ligand HABs HABs MABs LABs LABs HABs after blockade
11C-(R)-PK11195 0.7 0.8 0.9 0.5 26% 27%
11C–PBR28 4.3 1.2 0.5b Not reliably measured Not reliably measured [6] 25%
11C–DPA-713 3.6 7.3 3.4b 1.8b 25% 13%
11C–ER176 3.3 4.2 3.4b 1.4b ~0% 6%
  1. HABs high-affinity binders, MABs mixed-affinity binders, LABs low-affinity binders, V T total distribution volume (mL ∙ cm−3), BP ND specific-to-non-displaceable uptake ratio (unitless)
  2. a% increase of V T in last 40 min of a 90-min scan (i.e., 50–90 min)
  3. bCalculated from V T in MABs or LABs and V ND measured in HABs after blockade with XBD173 (that is, these BP ND values were not measured directly by administering XBD173 in MABs and LABs)