title: Effect of time-of-flight and point spread function modeling on detectability of myocardial defects in PET.
abstract: OBJECTIVE
  A study was designed to investigate the impact of time-of-flight (TOF) and point spread function (PSF) modeling on the detectability of myocardial defects.
  
  
  METHODS
  Clinical FDG-PET data were used to generate populations of defect-present and defect-absent images. Defects were incorporated at three contrast levels, and images were reconstructed by ordered subset expectation maximization (OSEM) iterative methods including ordinary Poisson, alone and with PSF, TOF, and PSF+TOF. Channelized Hotelling observer signal-to-noise ratio (SNR) was the surrogate for human observer performance.
  
  
  RESULTS
  For three iterations, 12 subsets, and no postreconstruction smoothing, TOF improved overall defect detection SNR by 8.6% as compared to its non-TOF counterpart for all the defect contrasts. Due to the slow convergence of PSF reconstruction, PSF yielded 4.4% less SNR than non-PSF. For reconstruction parameters (iteration number and postreconstruction smoothing kernel size) optimizing observer SNR, PSF showed larger improvement for faint defects. The combination of TOF and PSF improved mean detection SNR as compared to non-TOF and non-PSF counterparts by 3.0% and 3.2%, respectively.
  
  
  CONCLUSIONS
  For typical reconstruction protocol used in clinical practice, i.e., less than five iterations, TOF improved defect detectability. In contrast, PSF generally yielded less detectability. For large number of iterations, TOF+PSF yields the best observer performance.
authors.affiliation: A*STAR-NUS Clinical Imaging and Research Centre (CIRC), Singapore 117599, Singapore.
authors.forename: Joshua
authors.initials: J
authors.lastname: Schaefferkoetter
authors.affiliation: Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Radiology Department, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Ouyang
authors.affiliation: Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Radiology Department, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Yothin
authors.initials: Y
authors.lastname: Rakvongthai
authors.affiliation: Radiology Department, Harvard Medical School, Boston, Massachusetts 02115 Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples 80131, Italy; and SDN Foundation, Institute of Diagnostic and Nuclear Development, Naples 80142, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Nappi
authors.affiliation: Center for Advanced Medical Imaging Sciences, Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, Massachusetts 02114 and Radiology Department, Harvard Medical School, Boston, Massachusetts 02115.
authors.forename: Georges
authors.initials: G
authors.lastname: El Fakhri
mesh_terms: D009202:Cardiomyopathies / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D003198:Computer Simulation; D019788:Fluorodeoxyglucose F18; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008962:Models, Theoretical; D016012:Poisson Distribution; D049268:Positron-Emission Tomography / Q000379:methods*
chemical_list: D019788:Fluorodeoxyglucose F18