title: Semiquantification of the peripheral-type benzodiazepine ligand [11C]PK11195 in normal human brain and application in multiple sclerosis patients.
abstract: OBJECTIVE
  [11C]PK11195 is a peripheral-benzodiazepine-receptor radioligand used for detection of microglial inflammation. Normal uptake by means of semiquantification was measured in order to establish reference data. The applicability of this semiquantitative approach was tested in three multiple sclerosis patients.
  
  
  METHODS
  Seven controls and three patients underwent MR and PET scanning. Coregistered static scans 40 minutes postinjection of [11C]PK11195 were used for assessment of relative ligand uptake by comparison to whole-brain uptake.
  
  
  RESULTS
  For static scans acquired in near steady-state, the relative ligand uptake was significantly higher in gray matter structures as compared to the whole brain (ratio: 1.041 +/- 0.06, p = 0.036) whereas it was comparable in white matter (1.010 +/- 0.035). Intersubject reproducibility was 11.4% and 12.9% for white and grey matter. Intrasubject reproducibility was of the same order: 14.0% and 14.5% respectively. In two clinically active patients with Gadolinium-positive T1-weighted lesions on MRI the focal ligand uptake was significantly increased (1.36 and 1.14, p = 0.001). In one clinically stable patient, the uptake value corresponding with a T2-weighted MR lesion was not different from normal brain measurements.
  
  
  CONCLUSIONS
  The current investigations show that normal brain uptake of [11C]PK11195 is very low and shows the feasibility of a semiquantitative method which can be applied to larger cohorts of patients subgroups.
authors.affiliation: Department of Neurology, Ghent University Hospital, Ghent, Belgium. jan.debruyne@rug.ac.be
authors.forename: Jan C
authors.initials: JC
authors.lastname: Debruyne
authors.forename: Koen J
authors.initials: KJ
authors.lastname: Van Laere
authors.forename: Jan
authors.initials: J
authors.lastname: Versijpt
authors.forename: Filip
authors.initials: F
authors.lastname: De Vos
authors.forename: Johan Keppens
authors.initials: JK
authors.lastname: Eng
authors.forename: Karel
authors.initials: K
authors.lastname: Strijckmans
authors.forename: Patrick
authors.initials: P
authors.lastname: Santens
authors.forename: Eric
authors.initials: E
authors.lastname: Achten
authors.forename: Guido
authors.initials: G
authors.lastname: Slegers
authors.forename: Jacob
authors.initials: J
authors.lastname: Korf
authors.forename: Rudi A
authors.initials: RA
authors.lastname: Dierckx
authors.forename: Jacques L
authors.initials: JL
authors.lastname: De Reuck
mesh_terms: D000328:Adult; D001569:Benzodiazepines; D001921:Brain / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007546:Isoquinolines / Q000493:pharmacokinetics*; D008024:Ligands; D008279:Magnetic Resonance Imaging; D008297:Male; D009103:Multiple Sclerosis / Q000000981:diagnostic imaging* / Q000378:metabolism; D011859:Radiography; D015203:Reproducibility of Results; D014055:Tomography, Emission-Computed
chemical_list: D007546:Isoquinolines; D008024:Ligands; D001569:Benzodiazepines; C037850:PK 11195