title: Evaluation of iterative reconstruction (OSEM) versus filtered back-projection for the assessment of myocardial glucose uptake and myocardial perfusion using dynamic PET.
abstract: OBJECTIVE
  Iterative reconstruction methods based on ordered-subset expectation maximisation (OSEM) has replaced filtered backprojection (FBP) in many clinical settings owing to the superior image quality. Whether OSEM is as accurate as FBP in quantitative positron emission tomography (PET) is uncertain. We compared the accuracy of OSEM and FBP for regional myocardial (18)F-FDG uptake and (13)NH(3) perfusion measurements in cardiac PET.
  
  
  METHODS
  Ten healthy volunteers were studied. Five underwent dynamic (18)F-FDG PET during hyperinsulinaemic-euglycaemic clamp, and five underwent (13)NH(3) perfusion measurement during rest and adenosine-induced hyperaemia. Images were reconstructed using FBP and OSEM +/- an 8-mm Gaussian post-reconstruction filter.
  
  
  RESULTS
  Filtered and unfiltered images showed agreement between the reconstruction methods within +/-2SD in Bland-Altman plots of K (i) values. The use of a Gaussian filter resulted in a systematic underestimation of K (i) in the filtered images of 11%. The mean deviation between the reconstruction methods for both unfiltered and filtered images was 1.3%. Agreement within +/-2SD between the methods was demonstrated for perfusion rate constants up to 2.5 min(-1), corresponding to a perfusion of 3.4 ml g(-1) min(-1). The mean deviation between the two methods for unfiltered data was 2.7%, and for filtered data, 5.3%.
  
  
  CONCLUSIONS
  The (18)F-FDG uptake rate constants showed excellent agreement between the two reconstruction methods. In the perfusion range up to 3.4 ml g(-1) min(-1), agreement between (13)NH(3) perfusion obtained with OSEM and FBP was acceptable. The use of OSEM for measurement of perfusion values higher than 3.4 ml g(-1) min(-1) requires further evaluation.
authors.affiliation: Department of Cardiology B, Aarhus University Hospital, Aarhus, Denmark. soren@pet.auh.dk
authors.forename: Hanne M
authors.initials: HM
authors.lastname: Søndergaard
authors.forename: Mette Marie
authors.initials: MM
authors.lastname: Madsen
authors.forename: Karin
authors.initials: K
authors.lastname: Boisen
authors.forename: Morten
authors.initials: M
authors.lastname: Bøttcher
authors.forename: Ole
authors.initials: O
authors.lastname: Schmitz
authors.forename: Torsten T
authors.initials: TT
authors.lastname: Nielsen
authors.forename: Hans Erik
authors.initials: HE
authors.lastname: Bøtker
authors.forename: Søren B
authors.initials: SB
authors.lastname: Hansen
mesh_terms: D000465:Algorithms; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics*; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010477:Perfusion / Q000379:methods; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18