title: Signal extraction and separation in in vivo animal PET studies with masked volumewise principal-component analysis.
abstract: The standardized uptake value is commonly used as a tool to supplement visual interpretation and to quantify the images acquired from static in vivo animal PET. The preferred approach for analyzing PET data is either to sum the images and calculate the standardized uptake value or to use kinetic modeling. The aim of this study was to investigate the performance of masked volumewise principal-component analysis (MVW-PCA) used in dynamic in vivo animal PET studies to extract and separate signals with different kinetic behaviors.
  
  
  METHODS
  PET data were acquired with a small-animal PET scanner and a fluorine tracer in a study of rats and mice. After acquisition, the data were reconstructed by use of 4 time protocols with different frame lengths. Data were analyzed by use of MVW-PCA with applied noise prenormalization and a new masking technique developed in this study.
  
  
  RESULTS
  The resulting principal-component images showed a clear separation of the activity in the spine into the first MVW-PCA component and the activity in the kidneys into the second MVW-PCA component. In addition, the different time protocols were shown to have little or no impact on the results obtained with MVW-PCA.
  
  
  CONCLUSIONS
  MVW-PCA can efficiently separate different kinetic behaviors into different principal-component images. Moreover, MVW-PCA is a stable technique in the sense that the time protocol chosen has only a small impact on the resulting principal-component images.
authors.affiliation: 1Uppsala Applied Science Laboratory (UASL), GE Healthcare, Uppsala, Sweden; and 2Centre for Image Analysis, Uppsala University, Uppsala, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Engbrant
authors.forename: Azita
authors.initials: A
authors.lastname: Monazzam
authors.forename: Per-Edvin
authors.initials: PE
authors.lastname: Svensson
authors.forename: Johan
authors.initials: J
authors.lastname: Olsson
authors.forename: Ewert
authors.initials: E
authors.lastname: Bengtsson
authors.forename: Pasha
authors.initials: P
authors.lastname: Razifar
mesh_terms: D000818:Animals; D005461:Fluorine; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D051379:Mice; D049268:Positron-Emission Tomography / Q000379:methods*; D025341:Principal Component Analysis; D011849:Radioactive Tracers; D051381:Rats; D013997:Time Factors
chemical_list: D011849:Radioactive Tracers; D005461:Fluorine