PET visualization of microglia in multiple sclerosis patients using [11C]PK11195

Eur J Neurol. 2003 May;10(3):257-64. doi: 10.1046/j.1468-1331.2003.00571.x.


Activated microglia are involved in the immune response of multiple sclerosis (MS). The peripheral benzodiazepine receptor (PBR) is expressed on microglia and up-regulated after neuronal injury. [11C]PK11195 is a positron emission tomography (PET) radioligand for the PBR. The objective of the present study was to investigate [11C]PK11195 imaging in MS patients and its additional value over magnetic resonance imaging (MRI) concerning the immuno-pathophysiological process. Seven healthy and 22 MS subjects were included. Semiquantitative [11C]PK11195 uptake values were assessed with normalization on cortical grey matter. Uptake in Gadolinium-lesions was significantly increased compared with normal white matter. Uptake in T2-lesions was generally decreased, suggesting a PBR down-regulation. However, uptake values increased whenever a clinical or MR-relapse was present, suggestive for a dynamic process with a transient PBR up-regulation. During disease progression, an increase of normal-appearing white matter (NAWM) uptake was found, propagating NAWM as the possible real burden of disease. In conclusion, [11C]PK11195 and PET are able to demonstrate inflammatory processes with microglial involvement in MS.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Factors
  • Antineoplastic Agents* / metabolism
  • Antineoplastic Agents* / therapeutic use
  • Brain Mapping
  • Cohort Studies
  • Female
  • Humans
  • Isoquinolines* / metabolism
  • Isoquinolines* / therapeutic use
  • Magnetic Resonance Imaging / methods
  • Male
  • Microglia / diagnostic imaging
  • Microglia / metabolism*
  • Middle Aged
  • Multiple Sclerosis / diagnostic imaging
  • Multiple Sclerosis / metabolism*
  • Multiple Sclerosis / physiopathology*
  • Parietal Lobe / metabolism
  • Parietal Lobe / pathology
  • Parietal Lobe / physiopathology
  • Radioligand Assay / methods
  • Recurrence
  • Thalamus / diagnostic imaging
  • Thalamus / metabolism
  • Thalamus / pathology
  • Tomography, Emission-Computed / methods*


  • Antineoplastic Agents
  • Isoquinolines
  • PK 11195