title: Impact of the ECG gating method on ventricular volumes and ejection fractions assessed by cardiovascular magnetic resonance imaging.
abstract: OBJECTIVE
  Most MRI centers currently use prospective ECG triggering and fast gradient-echo sequences for image acquisition. Retrospectively gated sequences allow the coverage of the entire cardiac cycle. There is concern about whether ventricular volumes and ejection fraction (EF) differ according to the gating method used for image acquisition. We sought to evaluate the impact of the gating method on measurements of right and left ventricular volumes and EF in normal subjects.
  
  
  METHODS
  Fifteen 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-mn-thick slices using both prospective triggering and retrospective gating. Left and right ventricular volumes (EDV, ESV, SV) and EF were determined with a commercially available software package (Argus, Siemens).
  
  
  RESULTS
  EDV and SV calculated from short-axis images were significantly smaller with the prospectively triggered SSFP sequence (mean difference: EDV left: 13.9 +/- 4.4 mL, p < 0.0001; SV left: 13.5 +/- 4.8 mL, p < 0.0001; EDV right: 14.2 +/- 3.9 mL, p < 0.0001; SV right: 14.7 +/- 5.9 mL, p < 0.0001). EF was significantly smaller for the right ventricle (mean difference -3.6 +/- 3.3%, p = 0.0008) and the left ventricle (mean difference -2.3 +/- 3.3%, p = 0.02). ESV remained unchanged (mean difference: ESV left: 0.47 +/- 3.5 mL, p = 0.6179; right ESV: 0.5 +/- 3.7 mL, p = 0.6083).
  
  
  CONCLUSIONS
  The gating method has a significant impact on volume and EF measurements. The global ventricular EF is underestimated by using the prospective triggering technique. However, the difference in the left ventricle is small and might not be of clinical relevance.
authors.affiliation: Department of Cardiology and Angiology, Marienhospital, University of Bochum, Herne, NRW, Germany. burkhard.sievers@gmx.de
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: D002302:Cardiac Output / Q000502:physiology*; D003971:Diastole / Q000502:physiology; D005260:Female; D006352:Heart Ventricles / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D013599:Systole / Q000502:physiology