title: "W-shaped" volume curve with gated myocardial perfusion single photon emission computed tomography.
abstract: OBJECTIVE
  Gating errors (GEs) with ECG gated myocardial SPECT (G-SPECT) may occur irrespective of the presence or absence of arrhythmias. We evaluated the impact of GEs on both reconstructed tomograms and left ventricular ejection fraction (LVEF) derived from G-SPECT, and searched for clues to identify these errors.
  
  
  METHODS
  We studied 2 GE patients, 10 normal subjects (NLs), and 10 atrial fibrillation patients. Stress technetium-99m sestamibi G-SPECT was performed. Left ventricular (LV) contraction was evaluated in the beating slices. LVEF was calculated with G-SPECT using QGS (Cedars-Sinai, Los Angels) and p-FAST (Sapporo Medical University, Japan), and compared with that obtained by echocardiography (ECHO). LV volume curves were created by QGS and p-FAST. The heart rates (HRs) were calculated from the acquired images, and compared with their resting HRs. The mean count density of the myocardium was measured and time-activity curves were created.
  
  
  RESULTS
  In patients with GEs, bi-phasic LV contraction was demonstrated with fading-out towards end-diastole. G-SPECT underestimated LVEF compared to ECHO by 10% or more. The volume curves appeared "W-shaped." The HRs from the images were slower than the resting HRs. The count density decrement from frame #1 to #8 was larger than that of NLs. The time-activity curves were different in shape from those of NLs.
  
  
  CONCLUSIONS
  G-SPECT underestimates LVEF in patients with GEs. These errors can be identified with a combination of visual inspection of beating slices, time-volume curves, and time-activity curves. Monitoring the HR is a clue for anticipating and avoiding these errors.
authors.affiliation: Division of Nuclear Medicine, Department of Radiology, St. Luke's-Roosevelt Hospital Center, Columbia University College of Physicians and Surgeons, New York, USA. tkkasai@jikei.ac.jp
authors.forename: Tokuo
authors.initials: T
authors.lastname: Kasai
authors.forename: E Gordon
authors.initials: EG
authors.lastname: DePuey
authors.forename: Irwin
authors.initials: I
authors.lastname: Sponder
mesh_terms: D016477:Artifacts; D001281:Atrial Fibrillation / Q000150:complications / Q000000981:diagnostic imaging*; D003951:Diagnostic Errors / Q000517:prevention & control*; D004562:Electrocardiography / Q000379:methods*; D015637:Gated Blood-Pool Imaging / Q000379:methods*; D006801:Humans; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology