title: Quantitative assessment of left atrial volume by electrocardiographic-gated contrast-enhanced multidetector computed tomography.
abstract: BACKGROUND
  Left atrial (LA) volume is a predictor of cardiovascular events. Information on LA volume is available on contrast-enhanced electrocardiogram (EGC)-gated multidetector computed tomography (MDCT) scans.
  
  
  OBJECTIVE
  To assess interobserver and intraobserver reproducibility of 3-dimensional threshold-based volume (3DTV) and 2-dimensional (2D) measurements for the assessment of LA volumes with contrast-enhanced cardiac 64-slice MDCT.
  
  
  METHODS
  Contrast-enhanced 64-slice MDCT (0.6-mm slice thickness, 120 kVp, 850 mAseff) was performed in 96 consecutive subjects (mean age 52 years; 48% women) as a subset of the Rule Out Myocardial Infarction using Computer Assisted Tomography trial. Two observers independently measured maximal (LAV(max)) and minimal (LAV(min)) LA volumes with (1) a modified Simpson's method (3DTV) based on delineation of LA areas in axial slices and (2) estimated LA volumes typically used in 2D echocardiography (area length and prolate ellipse). Interobserver and intraobserver reproducibility for each method as well as correlations between the methods were calculated.
  
  
  RESULTS
  Interobserver (n = 96) and intraobserver (n = 20) variability was significantly lower for 3DTV (8%) than for area length (13%; P < 0.001) or prolate ellipse (16%; P < 0.001). 2D-based measurements rendered significantly lower LA volumes than did 3DTV (area length: -17% and -22%; prolate ellipse: -43% and -46% for LAV(max) and LAV(min), respectively; P < 0.001 for all). By 3DTV, mean LA volume was 90.4 +/- 24.5 mL for LAV(max) and 52.5 +/- 17.6 mL for LAV(min).
  
  
  CONCLUSIONS
  ECG-gated contrast-enhanced cardiac MDCT offers volumetric assessment of LA volume with excellent reproducibility without additional contrast administration or radiation exposure. 3D measures of LA volume are more reproducible and render larger volumes than 2D-derived estimates, typically used in echocardiography.
authors.affiliation: Cardiac MR PET CT Program, Department of Radiology and Division of Cardiology, Massachusetts General Hospital, 165 Cambridge Street, Suite 400, Boston, MA 02114, USA.
authors.forename: Amir A
authors.initials: AA
authors.lastname: Mahabadi
authors.forename: Bharat
authors.initials: B
authors.lastname: Samy
authors.forename: Sujith K
authors.initials: SK
authors.lastname: Seneviratne
authors.forename: Michael H
authors.initials: MH
authors.lastname: Toepker
authors.forename: Fabian
authors.initials: F
authors.lastname: Bamberg
authors.forename: Udo
authors.initials: U
authors.lastname: Hoffmann
authors.forename: Quynh A
authors.initials: QA
authors.lastname: Truong