title: Optimization of single injection liver arterial phase gadolinium enhanced MRI using bolus track real-time imaging.
abstract: OBJECTIVE
  To measure contrast agent enhancement kinetics in the liver and to further evaluate and develop an optimized gadolinium enhanced MRI using a single injection real-time bolus-tracking method for reproducible imaging of the transient arterial-phase.
  
  
  METHODS
  A total of 18 subjects with hypervascular liver lesions were imaged with four dimensional (4D) perfusion scans to measure time-to-peak (TTP) delays of arterial (aorta-celiac axis), liver parenchyma, liver lesion, portal, and hepatic veins. Time delays were calculated from the TTP-aorta signal, and then related to the gradient echo (GRE) k-space acquisition design, to determine optimized timing for real-time bolus-track triggering methodology. As another measure of significance, 200 clinical patients were imaged with 3D-GRE using either a fixed time-interval or by individualized arterial bolus real-time triggering. Bolus TTP-aorta was calculated and arterial-phase acquisitions were compared for accuracy and reproducibility using specific vascular enhancement indicators.
  
  
  RESULTS
  The mean bolus transit-time to peak-lesion contrast was 8.1 ± 2.7 seconds following arterial detection, compared to 32.1 ± 5.4 seconds from contrast injection, representing a 62.1% reduction in the time-variability among subjects (N = 18). The real-time bolus-triggered technique more consistently captured the targeted arterial phase (94%), compared to the fixed timing technique (73%), representing an expected improvement of timing accuracy in 28% of patients (P = 0.0001389).
  
  
  CONCLUSIONS
  Our results show detailed timing window analysis required for optimized arterial real-time bolus-triggering acquisition of transient arterial phase features of liver lesions, with optimized arterial triggering expected to improve reproducibility in a significant number of patients.
authors.affiliation: Department of Radiology, Emory Healthcare, Inc., Atlanta, Georgia, USA.
authors.forename: Puneet
authors.initials: P
authors.lastname: Sharma
authors.forename: Bobby
authors.initials: B
authors.lastname: Kalb
authors.forename: Hiroumi D
authors.initials: HD
authors.lastname: Kitajima
authors.forename: Khalil N
authors.initials: KN
authors.lastname: Salman
authors.forename: Bobbie
authors.initials: B
authors.lastname: Burrow
authors.forename: Gaye L
authors.initials: GL
authors.lastname: Ray
authors.forename: Diego R
authors.initials: DR
authors.lastname: Martin
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003198:Computer Simulation; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006499:Hepatic Artery / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007269:Injections, Intra-Arterial; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008536:Meglumine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D008875:Middle Aged; D008954:Models, Biological; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine