title: How much are atrial volumes and ejection fractions assessed by cardiac magnetic resonance imaging influenced by the ECG gating method?
abstract: OBJECTIVE
  Most magnetic resonance imaging (MRI) centers currently use prospective electrocardiographic (ECG) triggering for image acquisition. Retrospectively gated sequences allow the coverage of the entire cardiac cycle. It has been recently shown that ventricular volumes and ejection fraction (EF) differ according to the gating method used for image acquisition. The authors sought to evaluate how much measurements of atrial volumes and EF differ depending on the gating method.
  
  
  METHODS
  Eighteen subjects with no cardiovascular disease were investigated by MRI using a 1.5 Tesla scanner. Images were acquired with a gradient-echo sequence with steady-state free precession (SSFP) using the standard short-axis method for volume and EF measurements. Images were acquired with 6 mm thick slices using both prospective triggering and retrospective gating. Left and right atrial volumes (end diastolic volume [EDV]; end systolic volume [ESV]; stroke volume [SV]) and EF were determined with a commercially available software package.
  
  
  RESULTS
  ESV was significantly smaller with the retrospectively gated SSFP sequence than with the prospectively triggered sequence (mean difference: ESV left 3.97 +/- 1.3 ml, p < 0.0001; ESV right 4.34 +/- 1.8 ml, p < 0.0001). EF and SV were significantly smaller with prospective triggering (mean difference: EF left -5.94 +/- 0.9%, p < 0.0001; EF right -5.52 +/- 1.3 %, p < 0.0001; SV left -3.99 +/- 1.3 ml, p < 0.0001; SV right -4.32 +/- 1.9 ml, p < 0.0001). EDV remained unchanged (mean difference: EDV left -0.03 +/- 0.8 ml, p = 0.902; right EDV 0.04 +/- 0.7 ml, p = 0.882).
  
  
  CONCLUSIONS
  The gating method has a significant impact on atrial volume and EF measurements. Atrial EF is underestimated by using the prospective triggering technique.
authors.affiliation: Department of Cardiology and Angiology, Marienhospital, University of Bochum, Herne, NRW Germany. burkhard.sievers@duke.edu
authors.forename: Burkhard
authors.initials: B
authors.lastname: Sievers
authors.forename: Marvin
authors.initials: M
authors.lastname: Addo
authors.forename: Simon
authors.initials: S
authors.lastname: Kirchberg
authors.forename: Asli
authors.initials: A
authors.lastname: Bakan
authors.forename: Binu
authors.initials: B
authors.lastname: John-Puthenveettil
authors.forename: Ulrich
authors.initials: U
authors.lastname: Franken
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Trappe
mesh_terms: D002306:Cardiac Volume; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006325:Heart Atria / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013318:Stroke Volume; D013599:Systole