title: QGS ejection fraction reproducibility in gated SPECT comparing pre-filtered and post-filtered reconstruction.
abstract: BACKGROUND
  The aim of this investigation was to compare the QGS determined functional parameters using pre-filtering to that using post-filtering in the gated myocardial perfusion single photon emission computed tomography (SPECT) reconstruction process.
  
  
  METHODS
  A total of 25 patient files were examined, each with both a gated rest and gated stress study, and were reconstructed using two strategies. The first employed pre-filtering with a Butterworth low pass filter (order 4.0 and cut-off 0.21) and the second employed post-filtering with a Butterworth low pass filter (order 5.0 and cut-off 0.21). Following reconstruction and reorientation, gated short axis slices were evaluated with QGS software.
  
  
  RESULTS
  The mean ejection fraction for the post-filtered data was 49.5% (95% CI, 45.8-53.1%) and for the pre-filtered data was 54.8% (95% CI, 51.4-58.1%). Excellent correlation was demonstrated between the pre- and post-filtered ejection fractions with a correlation coefficient of 0.964. The mean difference between matched pairs of pre- and post-filtered ejection fraction data was 5.3% (95% CI, 4.3-6.3%). The match pair t-test demonstrated a statistically significant difference between matched pairs (P<0.0001) and a statistically significant difference was shown between the means (P=0.005).
  
  
  CONCLUSIONS
  The impact of performing pre-filtering on data in the reconstruction process is significant with a 5.3% increase in the calculated ejection fraction over post-filtering. Clearly, this has the potential to undermine diagnostic and prognostic roles of functional parameters.
authors.affiliation: School of Clinical Sciences, Charles Sturt University, Wagga Wagga, Australia. jwheat@csu.edu.au
authors.forename: Janelle M
authors.initials: JM
authors.lastname: Wheat
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Currie
mesh_terms: D000465:Algorithms; D005080:Exercise Test; D015637:Gated Blood-Pool Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D012984:Software; D013318:Stroke Volume; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging*