title: Dynamic inversion time for improved 3D late gadolinium enhancement imaging in patients with atrial fibrillation.
abstract: OBJECTIVE
  High resolution three-dimensional (3D) late gadolinium enhancement (LGE) imaging is performed with single R-wave gating to minimize lengthy acquisition durations. In patients with atrial fibrillation (AF), heart rate variability results in variable magnetization recovery between sequence repeats, and image quality is often poor. In this study, we implemented and tested a dynamic inversion time (dynamic-TI) scheme designed to reduce sequence sensitivity to heart rate variations.
  
  
  METHODS
  An inversion-prepared 3D segmented gradient echo sequence was modified so that the TI varied automatically from beat-to-beat (dynamic-TI) based on the time since the last sequence repeat. 3D LGE acquisitions were performed in 17 patients prior to radio frequency ablation of persistent AF both with and without dynamic-TI. Qualitative image quality scores, blood signal-to-ghosting ratios (SGRs). and blood-myocardium contrast-to-ghosting ratios (CGRs) were compared.
  
  
  RESULTS
  Image quality scores were higher with dynamic-TI than without dynamic-TI (2.2 ± 0.9 vs. 1.8 ± 1.1, P = 0.008), as were blood-myocardium CGRs (13.8 ± 7.6 vs. 8.3 ± 6.1, P = 0.003) and blood SGRs (19.6 ± 8.5 vs. 13.1 ± 8.0, P = 0.003).
  
  
  CONCLUSIONS
  The dynamic-TI algorithm improves image quality of 3D LGE imaging in this difficult patient population by reducing the sequence sensitivity to RR interval variations
authors.affiliation: Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Trust, London, United Kingdom.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Keegan
authors.forename: Peter D
authors.initials: PD
authors.lastname: Gatehouse
authors.forename: Shouvik
authors.initials: S
authors.lastname: Haldar
authors.forename: Ricardo
authors.initials: R
authors.lastname: Wage
authors.forename: Sonya V
authors.initials: SV
authors.lastname: Babu-Narayan
authors.forename: David N
authors.initials: DN
authors.lastname: Firmin
mesh_terms: D000368:Aged; D000465:Algorithms; D001281:Atrial Fibrillation / Q000473:pathology*; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009942:Organometallic Compounds / Q000008:administration & dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol
keywords: 3D; arrhythmia; late gadolinium enhancement imaging