title: A multicenter evaluation of a new post-processing method with depth-dependent collimator resolution applied to full-time and half-time acquisitions without and with simultaneously acquired attenuation correction.
abstract: BACKGROUND
  The field of nuclear cardiology is limited by image quality and length of procedure. The use of depth-dependent resolution recovery algorithms in conjunction with iterative reconstruction holds promise to improve image quality and reduce acquisition time. This study compared the Astonish algorithm employing depth-dependent resolution recovery and iterative reconstruction to filtered backprojection (FBP) using both full-time (FTA) and half-time (HTA) data. Attenuation correction including scatter correction in conjunction with the Astonish algorithm was also evaluated.
  
  
  METHODS
  We studied 187 consecutive patients (132 with cardiac catheterization and 55 with low likelihood for CAD) from three nuclear cardiology laboratories who had previously undergone clinically indicated rest/stress Tc-99m sestamibi or tetrofosmin SPECT. Acquisition followed ASNC guidelines (64 projections, 20-25 seconds). Processing of the full-time data sets included FBP and Astonish (FTA). A total of 32 projection data sets were created by stripping the full-time data sets and processing with Astonish (HTA). Attenuation correction was applied to both full-time and half-time Astonish-processed images (FTA-AC and HTA-AC, respectively). A consensus interpretation of three blinded readers was performed for image quality, interpretative certainty, and diagnostic accuracy, as well as severity and reversibility of perfusion and functional parameters.
  
  
  RESULTS
  Full-time and half-time Astonish processing resulted in a significant improvement in image quality in comparison with FBP. Stress and rest perfusion image quality (excellent or good) were 85%/80% (FBP), 98%/95% (FTA), and 95%/92% (HTA), respectively (p < 0.001). Interpretative certainty and diagnostic accuracy were similar with FBP, FTA, and HTA. Left ventricular functional data were not different despite a slight reduction in half-time gated image quality. Application of attenuation correction resulted in similar image quality and improved normalcy (FTA vs. FTA-AC: 76% vs. 95%; HTA vs. HTA-AC: 76% vs. 100%) and specificity (FTA vs. FTA-AC: 62% vs. 78%; HTA vs. HTA-AC: 63% vs. 84%) (p < 0.01 for all comparisons).
  
  
  CONCLUSIONS
  Astonish processing, which incorporates depth-dependent resolution recovery, improves image quality without sacrificing interpretative certainty or diagnostic accuracy. Application of simultaneously acquired attenuation correction, which includes scatter correction, to full-time and half-time images processed with this method, improves specificity and normalcy while maintaining high image quality.
authors: Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA.
authors: Carmelo V
authors: CV
authors: Venero
authors: Gary V
authors: GV
authors: Heller
authors: Timothy M
authors: TM
authors: Bateman
authors: A Iain
authors: AI
authors: McGhie
authors: Alan W
authors: AW
authors: Ahlberg
authors: Deborah
authors: D
authors: Katten
authors: Staci A
authors: SA
authors: Courter
authors: Robert J
authors: RJ
authors: Golub
authors: James A
authors: JA
authors: Case
authors: S James
authors: SJ
authors: Cullom
mesh_terms: D000465:Algorithms; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000209:etiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012984:Software; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D014481:United States