title: Factors affecting left ventricular ejection fraction using automated quantitative gated SPECT.
abstract: BACKGROUND
  Factors affecting the accuracy of left ventricular ejection fraction (LVEF) quantification using automated quantitative gated SPECT have not been adequately investigated in patients in the clinical setting. Therefore, the authors studied the effect of defect size and Tc-99m tetrofosmin dose on the accuracy of LVEF calculation using the automated QGS program.
  
  
  METHODS
  Thirty-two consecutive patients underwent gated rest and stress myocardial perfusion SPECT after administration of 8 and 27 mCi Tc-99m tetrofosmin, respectively. The LVEF was obtained for both the rest and stress studies using the QGS program and compared with the LVEF obtained using quantitative echocardiography performed within 2 weeks. Myocardial perfusion defects were recorded as scarring, ischemia, or mixed scarring and ischemia in 12 left ventricular segments. The defect size was evaluated by adding the number of affected segments.
  
  
  RESULTS
  The mean LVEF calculated using high-dose stress QGS, low-dose rest QGS, and echocardiography was 49.2% +/- 15%, 46.2% +/- 17% and 48.7% +/- 16.9% respectively, with no statistically significant differences. The LVEF obtained using high-dose stress QGS correlated better with echocardiography than did that obtained using low-dose rest QGS (r = 0.86 versus 0.76). In addition, when the high-dose stress LVEF in the 14 patients with normal myocardial perfusion was compared with that in 11 patients who had one- or two-segment perfusion defects, and 7 patients who had perfusion defects in > or = three segments, there was good correlation with echocardiography in the three patient groups (r = 0.85, 0.88, and 0.91, respectively).
  
  
  CONCLUSIONS
  Myocardial perfusion defects do not affect the accuracy of LVEF calculation using automated QGS. High-dose gated myocardial SPECT demonstrated better correlation with quantitative echocardiography LVEF results.
authors.affiliation: Department of Nuclear Medicine, Lyndon B. Johnson General Hospital and M.D. Anderson Cancer Center, Houston, Texas 77030, USA. igayed@di.mdacc.tmc.edu
authors.forename: Isis
authors.initials: I
authors.lastname: Gayed
authors.forename: Emma
authors.initials: E
authors.lastname: Cid
authors.forename: Fernando
authors.initials: F
authors.lastname: Boccalandero
authors.forename: Donald
authors.initials: D
authors.lastname: Podoloff
mesh_terms: D000328:Adult; D000368:Aged; D004176:Dipyridamole; D004305:Dose-Response Relationship, Drug; D005260:Female; D015637:Gated Blood-Pool Imaging / Q000379:methods*; D006331:Heart Diseases / Q000150:complications / Q000000981:diagnostic imaging; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D009943:Organophosphorus Compounds / Q000008:administration & dosage*; D015609:Organotechnetium Compounds / Q000008:administration & dosage*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013312:Stress, Physiological / Q000139:chemically induced; D013318:Stroke Volume; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000150:complications / Q000000981:diagnostic imaging*
chemical_list: D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; C078700:technetium tc-99m tetrofosmin; D004176:Dipyridamole