title: System matrix modelling of externally tracked motion.
abstract: OBJECTIVE
  In high-resolution emission tomography imaging, even small patient movements can considerably degrade image quality. The aim of this work was to develop a general approach to motion-corrected reconstruction of motion-contaminated data in the case of rigid motion (particularly brain imaging) which would be applicable to any PET scanner in the field, without specialized data-acquisition requirements.
  
  
  METHODS
  Assuming the ability to externally track subject motion during scanning (e.g., using the Polaris camera), we proposed to incorporate the measured rigid motion information into the system matrix of the expectation maximization reconstruction algorithm. Furthermore, we noted and developed a framework to incorporate the additional effect of motion on modifying the attenuation factors. A new mathematical brain phantom was developed and used along with elaborate combined Simset/GATE simulations to compare the proposed framework with the cases of no motion correction.
  
  
  CONCLUSIONS
  Clear qualitative and quantitative improvements were observed when incorporating the proposed framework. The method is very practical to implement for any scanner in the field, not requiring any hardware modifications or access to the list-mode acquisition capability.
authors.affiliation: Department of Radiology, School of Medicine, Johns Hopkins University, Baltimore, USA. arahmim1@jhmi.edu
authors.forename: Arman
authors.initials: A
authors.lastname: Rahmim
authors.forename: Ju-Chieh
authors.initials: JC
authors.lastname: Cheng
authors.forename: Katie
authors.initials: K
authors.lastname: Dinelle
authors.forename: Mikhail
authors.initials: M
authors.lastname: Shilov
authors.forename: W Paul
authors.initials: WP
authors.lastname: Segars
authors.forename: Olivier G
authors.initials: OG
authors.lastname: Rousset
authors.forename: Benjamin M W
authors.initials: BM
authors.lastname: Tsui
authors.forename: Dean F
authors.initials: DF
authors.lastname: Wong
authors.forename: Vesna
authors.initials: V
authors.lastname: Sossi
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging*; D003198:Computer Simulation; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008954:Models, Biological; D009038:Motion; D010363:Pattern Recognition, Automated / Q000379:methods; D011877:Radionuclide Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity