title: Doppler Ultrasound Triggering for Cardiovascular MRI at 3T in a Healthy Volunteer Study.
abstract: OBJECTIVE
  Electrocardiogram (ECG) triggering for cardiac magnetic resonance (CMR) may be influenced by electromagnetic interferences with increasing magnetic field strength. The aim of this study was to evaluate the performance of Doppler ultrasound (DUS) as an alternative trigger technique for CMR in comparison to ECG and pulse oximetry (POX) at 3T and using different sequence types.
  
  
  METHODS
  Balanced turbo field echo two-dimensional (2D) short axis cine CMR and 2D phase-contrast angiography of the ascending aorta was performed in 11 healthy volunteers at 3T using ECG, DUS, and POX for cardiac triggering. DUS and POX triggering were compared to the reference standard of ECG in terms of trigger quality (trigger detection and temporal variability), image quality [endocardial blurring (EB)], and functional measurements [left ventricular (LV) volumetry and aortic blood flow velocimetry].
  
  
  RESULTS
  Trigger signal detection and temporal variability did not differ significantly between ECG/DUS (I = 0.6) and ECG/POX (P = 0.4). Averaged EB was similar for ECG, DUS, and POX (pECG/DUS= 0.4, pECG/POX= 0.9). Diastolic EB was significantly decreased for DUS in comparison to ECG (P = 0.02) and POX (P = 0.04). The LV function assessment and aortic blood flow were not significantly different.
  
  
  CONCLUSIONS
  This study demonstrated the feasibility of DUS for gating human CMR at 3T. The magnetohydrodynamic effect did not significantly disturb ECG triggering in this small healthy volunteer study. DUS showed a significant improvement in diastolic EB but could not be identified as a superior trigger method. The potential benefit of DUS has to be evaluated in a larger clinical patient population.
authors.affiliation: University Medical Center Hamburg-Eppendorf, Center for Radiology and Endoscopy, Department of Diagnostic and Interventional Radiology, University Medical Center Hamburg-Eppendorf.
authors.forename: Fabian
authors.initials: F
authors.lastname: Kording
authors.forename: Jin
authors.initials: J
authors.lastname: Yamamura
authors.forename: Gunnar
authors.initials: G
authors.lastname: Lund
authors.forename: Friedrich
authors.initials: F
authors.lastname: Ueberle
authors.forename: Caroline
authors.initials: C
authors.lastname: Jung
authors.forename: Gerhard
authors.initials: G
authors.lastname: Adam
authors.forename: Bjoern Philip
authors.initials: BP
authors.lastname: Schoennagel
mesh_terms: D000328:Adult; D001011:Aorta / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D004562:Electrocardiography / Q000379:methods; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010092:Oximetry; D012016:Reference Values; D015203:Reproducibility of Results; D018608:Ultrasonography, Doppler / Q000379:methods*