title: Impact of photon energy recovery on the assessment of left ventricular volume using myocardial perfusion SPECT.
abstract: BACKGROUND
  Photon energy recovery (PER) is a spectral deconvolution technique validated for scatter removal in patients and phantom studies. The purpose of this study was to examine the impact of PER on left ventricular volume measurement based on myocardial perfusion single photon emission computed tomography (SPECT).
  
  
  RESULTS
  SPECT acquisitions were performed by use of a static cardiac phantom and in 25 patients after a rest injection of technetium 99m sestamibi by use of multiple energy windows (126-136, 137-144, and 145-154 keV). Data were successively reconstructed with and without PER, by use of iterative reconstruction and post-processing filtering (Butterworth filter; order, 5; cutoff, 0.30 cycles/pixel). Image contrast was evaluated in reconstructed data, and volumes were calculated by use of QGS. PER increased reconstructed image contrast from 62% +/- 2.7% to 84.3% +/- 5.7% in the phantom studies (P <.0001) and from 49% +/- 2% to 73% +/- 2% in patients (P <.0001). Although it remained underestimated (P <.0001), phantom volume was higher after PER correction compared with uncorrected data (50.9 +/- 0.8 mL vs 44.6 +/- 1 mL, P <.0001). The error in volume measurement was decreased by PER correction (16.6% +/- 1.3% vs 27% +/- 1.7% [uncorrected data], P <.0001). In patients, left ventricular volume increased from 83 +/- 10 mL to 91 +/- 10 mL (P <.0001), and the PER-induced volume increase was correlated with the image contrast increase (r = 0.61, P =.001). Finally, the percentage of volume increase was higher in patients with small left ventricular volumes.
  
  
  CONCLUSIONS
  PER has a significant impact on image contrast and left ventricular volume measurement by use of perfusion SPECT. PER improves the accuracy of phantom volume assessment. In patients, volume increase is correlated to image contrast increase and is higher in those with small ventricles.
authors.affiliation: Département de Médecine Nucléaire, CHU de Rouen et Centre Henri Becquerel, France. alain.manrique@rouen.fnclcc.fr
authors.forename: Alain
authors.initials: A
authors.lastname: Manrique
authors.forename: Anne
authors.initials: A
authors.lastname: Hitzel
authors.forename: Pierre
authors.initials: P
authors.lastname: Véra
mesh_terms: D000368:Aged; D000465:Algorithms; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000000981:diagnostic imaging*; D003324:Coronary Artery Disease / Q000150:complications / Q000000981:diagnostic imaging*; D005260:Female; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D018499:Linear Energy Transfer; D008297:Male; D008875:Middle Aged; D017785:Photons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013318:Stroke Volume; D015899:Tomography, Emission-Computed, Single-Photon / Q000295:instrumentation / Q000379:methods*; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology