title: Effect of physiological heart rate variability on quantitative T2 measurement with ECG-gated Fast Spin Echo (FSE) sequence and its retrospective correction.
abstract: OBJECTIVE
  Quantitative T2 measurement is applied in cardiac Magnetic Resonance Imaging (MRI) for the diagnosis and follow-up of myocardial pathologies. Standard Electrocardiogram (ECG)-gated fast spin echo pulse sequences can be used clinically for T2 assessment, with multiple breath-holds. However, heart rate is subject to physiological variability, which causes repetition time variations and affects the recovery of longitudinal magnetization between TR periods.
  
  
  METHODS
  The bias caused by heart rate variability on quantitative T2 measurements is evaluated for fast spin echo pulse sequence. Its retrospective correction based on an effective TR is proposed. Heart rate variations during breath-holds are provided by the ECG recordings from healthy volunteers. T2 measurements were performed on a phantom with known T2 values, by synchronizing the sequence with the recorded ECG. Cardiac T2 measurements were performed twice on six volunteers. The impact of T1 on T2 is also studied.
  
  
  RESULTS
  Maximum error in T2 is 26% for phantoms and 18% for myocardial measurement. It is reduced by the proposed compensation method to 20% for phantoms and 10% for in vivo measurements. Only approximate knowledge of T1 is needed for T2 correction.
  
  
  CONCLUSIONS
  Heart rate variability may cause a bias in T2 measurement with ECG-gated FSE. It needs to be taken into account to avoid a misleading diagnosis from the measurements.
authors: IADI, Université De Lorraine, Nancy, France; U947, INSERM, Nancy, France.
authors: Marion
authors: M
authors: de Roquefeuil
authors: Pierre-André
authors: PA
authors: Vuissoz
authors: Jean-Marie
authors: JM
authors: Escanyé
authors: Jacques
authors: J
authors: Felblinger
mesh_terms: D000328:Adult; D004452:Echocardiography; D005260:Female; D064368:Healthy Volunteers; D006321:Heart / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D009068:Movement; D009206:Myocardium / Q000473:pathology*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013997:Time Factors
keywords: ECG-gated FSE; Heart rate variability; Quantitative T(2) measurement