title: Multiphasic injection method for uniform prolonged vascular enhancement at CT angiography: pharmacokinetic analysis and experimental porcine model.
abstract: OBJECTIVE
  To determine if multiphasic injection provides uniform, prolonged vascular contrast medium enhancement at computed tomographic (CT) angiography.
  
  
  METHODS
  With a computer-based, compartmental model of the cardiovascular system, theoretic analysis was performed to estimate an injection algorithm for uniform, prolonged vascular enhancement. For algorithm validation, four pigs were scanned after intravenous injection of 50 or 70 mL of contrast medium (282 mg of iodine per milliliter). Uni-, bi-, and multiphasic injection schemes were tested. In most cases, the initial injection rate was 2 mL/sec. In each CT study, 27 dynamic images were acquired every 2 seconds at a fixed mid-abdominal aortic level. Time-enhancement curves were calculated. Injection duration, peak aortic enhancement, and enhancement uniformity (duration of enhancement achieved within 90% of the peak [90% DCE]) were evaluated.
  
  
  RESULTS
  Theoretic and experimental results agreed well. Compared with uniphasic injection, biphasic injection resulted in more prolonged enhancement but generated two enhancement peaks with a valley between, and multiphasic injection yielded more uniform and prolonged enhancement. With 50- and 70-mL multiphasic injections, respectively, injection duration increased by 32% and 51%, peak enhancement decreased by 19% and 18%, and 90% DCE increased by 81% and 94%.
  
  
  CONCLUSIONS
  Uniform, prolonged vascular enhancement, which is desirable for CT angiography and essential for steady-state quantification of blood volume in organs, can be achieved with multiphasic injection.
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO 63110, USA. baet@mir.wustl.edu
authors.forename: K T
authors.initials: KT
authors.lastname: Bae
authors.forename: H Q
authors.initials: HQ
authors.lastname: Tran
authors.forename: J P
authors.initials: JP
authors.lastname: Heiken
mesh_terms: D000792:Angiography; D000818:Animals; D001027:Aortography; D003198:Computer Simulation; D003287:Contrast Media / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007275:Injections, Intravenous; D007482:Iothalamate Meglumine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D008955:Models, Cardiovascular; D011856:Radiographic Image Enhancement; D012680:Sensitivity and Specificity; D013552:Swine; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D007482:Iothalamate Meglumine