title: Influence of heart rate and temporal resolution on left-ventricular volumes in cardiac multislice spiral computed tomography: a phantom study.
abstract: OBJECTIVE
  We sought to investigate the influence of heart rate and temporal resolution on the assessment of left-ventricular (LV) function with multislice spiral computed tomography (CT).
  
  
  METHODS
  A dynamic cardiac phantom was repeatedly scanned with a 64-slice CT scanner using a standardized scan protocol (64 x 0.6 mm, 120kV, 770mAs(eff), 330 milliseconds rotation time) at different simulated heart rates, ranging from 40 to 140 beats per minute. Images were reconstructed with an algorithm utilizing data from 1 to 4 cardiac cycles (RR intervals). Ejection fraction (EF), end-systolic, end-diastolic, and stroke volume as well as cardiac output were calculated. Results of the measurements were compared with the real volumes of the phantom. Interscan and intraobserver variability were calculated.
  
  
  RESULTS
  Using a monosegmental reconstruction algorithm, the temporal resolution was fixed to 165 milliseconds. With bi-, tri-, and quad-segmental image reconstruction, mean temporal resolution was 128.3 +/- 33.2 milliseconds, 103.3 +/- 49.2 milliseconds, and 87.8 +/- 81.5 milliseconds, respectively. Multisegmental image reconstruction resulted in a lower deviation when comparing measured and real volumes. Using mono-, bi-, tri-, and quad-segmental image reconstruction, the percent deviation between measured and real values for EF was 8.2%, 4.5%, 3.3%, and 3.4%, respectively. Applying multisegmental image reconstruction with improved temporal resolution the deviation decreased with increasing heart rate when compared with mono-segmental image reconstruction. Interscan and intraobserver variability for EF were 1.1% and 1.9%, respectively.
  
  
  CONCLUSIONS
  Enhanced temporal resolution improves the quantification of LV volumes in cardiac multislice spiral CT, enabling reliable assessment of LV volumes even at increased heart rates.
authors.affiliation: Department of Diagnostic Radiology, RWTH Aachen University, Germany. mahnken@rad.rwth-aachen.de
authors.forename: Andreas H
authors.initials: AH
authors.lastname: Mahnken
authors.forename: Christian
authors.initials: C
authors.lastname: Hohl
authors.forename: Christoph
authors.initials: C
authors.lastname: Suess
authors.forename: Herbert
authors.initials: H
authors.lastname: Bruder
authors.forename: Georg
authors.initials: G
authors.lastname: Mühlenbruch
authors.forename: Marco
authors.initials: M
authors.lastname: Das
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Günther
authors.forename: Joachim E
authors.initials: JE
authors.lastname: Wildberger
mesh_terms: D000465:Algorithms; D002306:Cardiac Volume / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D013318:Stroke Volume / Q000502:physiology*; D036542:Tomography, Spiral Computed / Q000295:instrumentation*; D016277:Ventricular Function, Left / Q000502:physiology*