title: Repeatability and reproducibility of phase analysis of gated single-photon emission computed tomography myocardial perfusion imaging used to quantify cardiac dyssynchrony.
abstract: BACKGROUND
  A novel method to quantify dyssynchrony has been developed using phase analysis of gated single-photon emission computed tomography perfusion imaging. We report on the effect of variability in image reconstruction on the phase analysis results (repeatability) and on the interobserver and intraobserver reproducibility of the technique.
  
  
  METHODS
  Phase standard deviation (SD) and bandwidth are phase indices that quantify dyssynchrony. To evaluate repeatability, raw data sets were processed twice in 50 patients with left ventricular dysfunction and 50 normal controls. To determine the optimal processing method, two replicated phase analysis results were obtained using automated and manual base parameter placement. Reproducibility of the phase analysis was determined using the data from 20 patients.
  
  
  RESULTS
  In normal controls, manual base parameter placement improves repeatability of the phase analysis as measured by the mean absolute difference between two reads for phase SD (12.0 degrees vs. 1.2 degrees , P<0.0001) and bandwidth (33.7 degrees vs. 3.6 degrees , P<0.0001). Repeatability is better for normal controls than for patients with left ventricular dysfunction for phase SD (1.2 degrees vs. 6.0 degrees , P<0.0001) and bandwidth (3.6 degrees vs. 26.5 degrees , P<0.0001). Reproducibility of the phase analysis is high as measured by the intraclass correlation coefficients for phase SD and bandwidth of 0.99 and 0.99 for the interobserver comparisons and 1.00 and 1.00 for the intraobserver comparisons.
  
  
  CONCLUSIONS
  A novel method to quantify dyssynchrony has been developed using gated single-photon emission computed tomography perfusion imaging. Manual base parameter placement reduces the effect that variability in image reconstruction has on phase analysis. A high degree of reproducibility of phase analysis is observed.
authors.affiliation: Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Trimble
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Velazquez
authors.forename: George L
authors.initials: GL
authors.lastname: Adams
authors.forename: Emily F
authors.initials: EF
authors.lastname: Honeycutt
authors.forename: Robert A
authors.initials: RA
authors.lastname: Pagnanelli
authors.forename: Huiman X
authors.initials: HX
authors.lastname: Barnhart
authors.forename: Ji
authors.initials: J
authors.lastname: Chen
authors.forename: Ami E
authors.initials: AE
authors.lastname: Iskandrian
authors.forename: Ernest V
authors.initials: EV
authors.lastname: Garcia
authors.forename: Salvador
authors.initials: S
authors.lastname: Borges-Neto
mesh_terms: D005260:Female; D015637:Gated Blood-Pool Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010477:Perfusion; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*