title: Influence of reconstruction algorithms on image quality in SPECT myocardial perfusion imaging.
abstract: BACKGROUND
  We investigated if image- and diagnostic quality in SPECT MPI could be maintained despite a reduced acquisition time adding Depth Dependent Resolution Recovery (DDRR) for image reconstruction. Images were compared with filtered back projection (FBP) and iterative reconstruction using Ordered Subsets Expectation Maximization with (IRAC) and without (IRNC) attenuation correction (AC).
  
  
  METHODS
  Stress- and rest imaging for 15 min was performed on 21 subjects with a dual head gamma camera (Infinia Hawkeye; GE Healthcare), ECG-gating with 8 frames/cardiac cycle and a low-dose CT-scan. A 9 min acquisition was generated using five instead of eight gated frames and was reconstructed with DDRR, with (IRACRR) and without AC (IRNCRR) as well as with FBP. Three experienced nuclear medicine specialists visually assessed anonymized images according to eight criteria on a four point scale, three related to image quality and five to diagnostic confidence. Statistical analysis was performed using Visual Grading Regression (VGR).
  
  
  RESULTS
  Observer confidence in statements on image quality was highest for the images that were reconstructed using DDRR (P<0·01 compared to FBP). Iterative reconstruction without DDRR was not superior to FBP. Interobserver variability was significant for statements on image quality (P<0·05) but lower in the diagnostic statements on ischemia and scar. The confidence in assessing ischemia and scar was not different between the reconstruction techniques (P = n.s.).
  
  
  CONCLUSIONS
  SPECT MPI collected in 9 min, reconstructed with DDRR and AC, produced better image quality than the standard procedure. The observers expressed the highest diagnostic confidence in the DDRR reconstruction.
authors.affiliation: Department of Clinical Physiology, Department of Medical and Health Sciences/Cardiovascular Medicine, Regionostergotland, Linköping University, Linköping, Sweden.
authors.forename: Anette
authors.initials: A
authors.lastname: Davidsson
authors.affiliation: Department of Clinical Physiology, Department of Medical and Health Sciences/Cardiovascular Medicine, Regionostergotland, Linköping University, Linköping, Sweden.
authors.forename: Eva
authors.initials: E
authors.lastname: Olsson
authors.affiliation: Department of Clinical Physiology, Department of Medical and Health Sciences/Cardiovascular Medicine, Regionostergotland, Linköping University, Linköping, Sweden.
authors.forename: Jan
authors.identifier: http://orcid.org/0000-0002-5716-5098
authors.initials: J
authors.lastname: Engvall
authors.affiliation: Department of Medical Physics, Karolinska University Hospital, Huddinge, Stockholm, Sweden.
authors.forename: Agnetha
authors.initials: A
authors.lastname: Gustafsson
mesh_terms: D000241:Adenosine / Q000008:administration & dosage; D000328:Adult; D000368:Aged; D000465:Algorithms; D001642:Bicycling; D055424:Cardiac-Gated Imaging Techniques; D004562:Electrocardiography; D005080:Exercise Test; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D015588:Observer Variation; D009943:Organophosphorus Compounds / Q000008:administration & dosage; D015609:Organotechnetium Compounds / Q000008:administration & dosage; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015203:Reproducibility of Results; D000072098:Single Photon Emission Computed Tomography Computed Tomography; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D014665:Vasodilator Agents; C078700:technetium tc-99m tetrofosmin; D000241:Adenosine
keywords: 
  MPI SPECT
  ; Visual Grading Regression; image quality; noise regularization; resolution recovery