Optimization of supervised cluster analysis for extracting reference tissue input curves in (R)-[(11)C]PK11195 brain PET studies

J Cereb Blood Flow Metab. 2012 Aug;32(8):1600-8. doi: 10.1038/jcbfm.2012.59. Epub 2012 May 16.


Performance of two supervised cluster analysis (SVCA) algorithms for extracting reference tissue curves was evaluated to improve quantification of dynamic (R)-[(11)C]PK11195 brain positron emission tomography (PET) studies. Reference tissues were extracted from images using both a manually defined cerebellum and SVCA algorithms based on either four (SVCA4) or six (SVCA6) kinetic classes. Data from controls, mild cognitive impairment patients, and patients with Alzheimer's disease were analyzed using various kinetic models including plasma input, the simplified reference tissue model (RPM) and RPM with vascular correction (RPMV(b)). In all subject groups, SVCA-based reference tissue curves showed lower blood volume fractions (V(b)) and volume of distributions than those based on cerebellum time-activity curve. Probably resulting from the presence of specific signal from the vessel walls that contains in normal condition a significant concentration of the 18 kDa translocation protein. Best contrast between subject groups was seen using SVCA4-based reference tissues as the result of a lower number of kinetic classes and the prior removal of extracerebral tissues. In addition, incorporation of V(b) in RPM improved both parametric images and binding potential contrast between groups. Incorporation of V(b) within RPM, together with SVCA4, appears to be the method of choice for analyzing cerebral (R)-[(11)C]PK11195 neurodegeneration studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Algorithms
  • Alzheimer Disease / diagnostic imaging*
  • Alzheimer Disease / physiopathology
  • Blood Volume / physiology
  • Carbon Radioisotopes
  • Cerebellum / blood supply
  • Cerebellum / diagnostic imaging
  • Cluster Analysis
  • Cognitive Dysfunction / diagnostic imaging*
  • Cognitive Dysfunction / physiopathology
  • Computer Simulation
  • Humans
  • Image Interpretation, Computer-Assisted
  • Isoquinolines* / pharmacokinetics
  • Middle Aged
  • Models, Neurological*
  • Positron-Emission Tomography / methods*
  • Protein Binding
  • Reference Values
  • Reproducibility of Results
  • Thalamus / blood supply
  • Thalamus / diagnostic imaging
  • Tissue Distribution
  • Young Adult


  • Carbon Radioisotopes
  • Isoquinolines
  • PK 11195