title: Image enhancement of severely hypoperfused myocardia for computation of tomographic ejection fraction.
abstract: Ejection fractions computed from 99mTc-sestamibi myocardial perfusion gated tomograms have demonstrated a high degree of accuracy and reproducibility. Although automated algorithms appear to provide reasonable endocardial outlines for patients over a broad spectrum of cardiac diseases, in cases of severe hypoperfusion, it is necessary to manually adjust contrast and brightness to judge whether borders are correct or must be altered.
  
  
  METHODS
  Midventricular horizontal and vertical long axis gated tomograms were generated for 116 studies chosen on the basis of extensive, severe myocardial perfusion defects. Automated software transformed cinematic tomograms into images demonstrating uniform appearance of the myocardium throughout the cardiac cycle. Transformed images were introduced to edge detection algorithms for subsequent calculation of ventricular volumes and ejection fractions.
  
  
  RESULTS
  Linear regression analysis demonstrated excellent intraobserver reproducibility for ejection fractions (r = 0.95) and volumes (r = 0.98). There was also good agreement of ejection fractions (r = 0.86) and volumes (r = 0.94) with values derived from an expert's manual drawings. In a subgroup of 22 patients, automated ejection fractions from transformed images demonstrated better agreement with independent first-pass values (r = 0.90) than did manual measurements derived from original data (r = 0.85).
  
  
  CONCLUSIONS
  Image enhancement algorithms succeeded in providing accurate, reproducible gated SPECT ejection fractions in the most difficult class of patients exhibiting severe hypoperfusion.
authors.affiliation: Department of Radiology, St. Luke's-Roosevelt Hospital and Columbia University College of Physicians and Surgeons, New York, New York 10025, USA.
authors.forename: K
authors.initials: K
authors.lastname: Nichols
authors.forename: E G
authors.initials: EG
authors.lastname: DePuey
authors.forename: A
authors.initials: A
authors.lastname: Rozanski
authors.forename: H
authors.initials: H
authors.lastname: Salensky
authors.forename: M I
authors.initials: MI
authors.lastname: Friedman
mesh_terms: D000368:Aged; D003326:Coronary Circulation; D003327:Coronary Disease / Q000000981:diagnostic imaging; D005260:Female; D015637:Gated Blood-Pool Imaging; D006801:Humans; D007089:Image Enhancement; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012044:Regression Analysis; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013318:Stroke Volume; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D017256:Technetium Tc 99m Sestamibi