title: Improved respiratory efficiency of 3D late gadolinium enhancement imaging using the continuously adaptive windowing strategy (CLAWS).
abstract: OBJECTIVE
  Acquisition durations of navigator-gated high-resolution three-dimensional late gadolinium enhancement studies may typically be up to 10 min, depending on the respiratory efficiency and heart rate. Implementation of the continuously adaptive windowing strategy (CLAWS) could increase respiratory efficiency, but the resulting non-smooth k-space acquisition order during gadolinium wash-out could result in increased artifact.
  
  
  METHODS
  Navigator-gated three-dimensional late gadolinium enhancement acquisitions were performed in 18 patients using tracking end-expiratory accept/reject (EE-ARA) and CLAWS algorithms in random order.
  
  
  RESULTS
  Retrospective analysis of the stored navigator data shows that CLAWS scan times are very close to (within 1%) or equal to the fastest achievable scan times while EE-ARA significantly extends the acquisition duration (P < 0.0001). EE-ARA acquisitions are 26% longer than CLAWS acquisitions (378 ± 104 s compared to 301 ± 85 s, P = 0.002). Image quality scores for CLAWS and EE-ARA acquisitions are not significantly different (4.1 ± 0.6 compared to 4.3 ± 0.6, P = ns). Numerical phantom simulations show that the non-uniform k-space ordering introduced by CLAWS results in slight, but not statistically significant, reductions in both blood signal-to-noise ratio (10%) and blood-myocardium contrast-to-noise ratio (12%).
  
  
  CONCLUSIONS
  CLAWS results in markedly reduced acquisition durations compared to EE-ARA without significant detriment to the image quality.
authors.affiliation: Cardiovascular Biomedical Research Unit, Royal Brompton and Harefield NHS Trust, London, UK.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Keegan
authors.forename: Permi
authors.initials: P
authors.lastname: Jhooti
authors.forename: Sonya V
authors.initials: SV
authors.lastname: Babu-Narayan
authors.forename: Peter
authors.initials: P
authors.lastname: Drivas
authors.forename: Sabine
authors.initials: S
authors.lastname: Ernst
authors.forename: David N
authors.initials: DN
authors.lastname: Firmin
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D016477:Artifacts; D003287:Contrast Media / Q000008:administration & dosage; D005246:Feedback; D005260:Female; D006330:Heart Defects, Congenital / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D009942:Organometallic Compounds / Q000008:administration & dosage; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C090600:gadobutrol