title: Left atrial volume and function assessment by magnetic resonance imaging.
abstract: Left Atrial Volume and Function Assessment.
  
  
  BACKGROUND
  In patients with atrial fibrillation undergoing catheter ablation, magnetic resonance imaging (MRI) can determine left atrial (LA) volume and function before and after ablation. The most accurate, but time consuming, method to determine LA volume is the multiple slice method (MSM), which involves manual tracing of LA area on each slice. The area length method (ALM) offers a simplified, but unvalidated, alternative for LA volume assessment by MRI. The aim of this study was to compare LA volume and function assessment by ALM with MSM.
  
  
  RESULTS
  MRI was performed before and after catheter ablation in 40 patients with atrial fibrillation (30 male, mean age 57 years). All patients had sinus rhythm during imaging. In total, 72 MRI scans were available. LA end-diastolic and end-systolic volumes (EDV, respectively ESV) were measured by both methods. LA function was determined by calculating LA ejection fraction (EF = (EDV-ESV)/EDV). Measured by ALM, mean LA EDV and ESV were significantly lower than using MSM (102 mL and 49 mL vs 111 mL and 65 mL, respectively, P < 0.001) with a larger difference in mean ESV than EDV (16 mL vs 9 mL). This resulted in an overestimation of LA EF by ALM with a mean of 11% (54% by ALM and 42% by MSM, P < 0.001). ALM correlated well with MSM for LA EDV and ESV (r = 0.77, respectively 0.85), and showed no significant difference in intraobserver and interobserver variability.
  
  
  CONCLUSIONS
  ALM significantly underestimates LA volumes and overestimates LA function, but correlates well with the more accurate MSM.
authors.affiliation: Department of Cardiology Department of Radiology, University Medical Center, Utrecht, The Netherlands.
authors.forename: Irene E
authors.initials: IE
authors.lastname: Hof
authors.forename: Birgitta K
authors.initials: BK
authors.lastname: Velthuis
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Van Driel
authors.forename: Fred H
authors.initials: FH
authors.lastname: Wittkampf
authors.forename: Richard N
authors.initials: RN
authors.lastname: Hauer
authors.forename: Peter
authors.initials: P
authors.lastname: Loh
mesh_terms: D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000503:physiopathology*; D005260:Female; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity