title: Patient-specific timing for bolus-chase peripheral MR angiography.
abstract: OBJECTIVE
  To develop a timing algorithm for three-station moving-table MR angiography of the peripheral arteries (pMRA) based on individual patient hemodynamics that optimizes arterial opacification and minimizes venous enhancement.
  
  
  METHODS
  Two separate patient cohorts were identified for this retrospective study. The first consisted of 71 patients for development of a patient specific timing algorithm to calculate multiple contrast agent bolus transit times at 1.5 Tesla using a spoiled gradient echo sequence. This timing data was applied to a separate group of 59 patients in which one of four predetermined pMRA protocols was performed based on a time-resolved MRA of the calves. Image quality was evaluated by two blinded readers grading venous enhancement and arterial opacification.
  
  
  RESULTS
  Transit time from abdominal aorta to foot (Ao-F) ranged from 5-46 s, with a mean of 17.8 ± 8.2 s. Arteriovenous window (AVW) transit time ranged from -5 to 65 s, with a mean of 18.3 ± 16.0 s. Ischemic patients had longer injection site-to-arterial transit times (25.6 versus 20.7 s; P < 0.01). Of the 59 patients who underwent diagnostic pMRA, 81 and 83% (two readers, respectively) showed no or minimal venous enhancement, and all of the exams were diagnostic. Venous enhancement grades were significantly greater (P < 0.04) for ischemic versus nonischemic patients.
  
  
  CONCLUSIONS
  Performing pMRA using a timing algorithm based on each patient's unique hemodynamics can minimize lower station venous enhancement.
authors.affiliation: Department of Radiology, University of Washington, Seattle, Washington, USA.|Radiology, Puget Sound VA Healthcare System, Seattle, Washington, USA.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Maki
authors.affiliation: Department of Radiology, University of Washington, Seattle, Washington, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Wilson
authors.affiliation: Reliable Staffing, Seattle, Washington, USA.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Cartright
authors.affiliation: Department of Radiology, University of Washington, Seattle, Washington, USA.|Radiology, Puget Sound VA Healthcare System, Seattle, Washington, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Bastawrous
mesh_terms: D000465:Algorithms; D001158:Arteries / Q000473:pathology*; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008536:Meglumine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D008875:Middle Aged; D008955:Models, Cardiovascular; D015233:Models, Statistical; D009942:Organometallic Compounds / Q000008:administration & dosage / Q000493:pharmacokinetics*; D066230:Patient-Specific Modeling; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; C064572:gadobenic acid; D008536:Meglumine
keywords: MR angiography; MRI; contrast agents; contrast timing; peripheral MR angiography