title: Prolongation and optimization of Doppler enhancement with a microbubble US contrast agent by using continuous infusion: preliminary experience.
abstract: OBJECTIVE
  To investigate whether continuous infusion of an echo-enhancing contrast agent for up to 15 minutes can provide uniform and prolonged enhancement.
  
  
  METHODS
  Six volunteers each received one bolus and three infusions of a microbubble contrast agent over 6-15 minutes at (a) a standard rate (mean, 2.08 mL/min), (b) a fast rate at twice the standard rate, and (c) a slow rate at half the standard rate. Spectral Doppler intensitometry of the femoral artery was performed for all infusions. Spectral Doppler ultrasound (US) scans of the femoral artery and color Doppler US scans of the carotid artery were subjectively assessed.
  
  
  RESULTS
  All infusions provided an equilibrium plateau of constant prolonged enhancement starting after 1-2 minutes and lasting until the end of the infusion. Enhancement at the plateau was +13 dB (slow rate), +17.1 dB (standard rate), and +18.3 dB (fast rate) compared with baseline. Saturation artifacts with infusions were markedly fewer than those with bolus injections. Dose effectiveness (duration of enhancement that measured at least 7.5 dB per gram of contrast agent) was markedly improved with the infusions, from 0.8 min/g for the bolus to 2.6 min/g for the slow infusion.
  
  
  CONCLUSIONS
  Continuous infusion of the microbubble contrast agent provided prolonged and uniform enhancement of Doppler signals and improved image quality by minimizing saturation artifacts.
authors.affiliation: Department of Imaging, Hammersmith Hospital, Imperial College, School of Medicine, London, England.
authors.forename: T
authors.initials: T
authors.lastname: Albrecht
authors.forename: A
authors.initials: A
authors.lastname: Urbank
authors.forename: M
authors.initials: M
authors.lastname: Mahler
authors.forename: A
authors.initials: A
authors.lastname: Bauer
authors.forename: C J
authors.initials: CJ
authors.lastname: Doré
authors.forename: M J
authors.initials: MJ
authors.lastname: Blomley
authors.forename: D O
authors.initials: DO
authors.lastname: Cosgrove
authors.forename: R
authors.initials: R
authors.lastname: Schlief
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D016477:Artifacts; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D002406:Catheterization, Peripheral; D003287:Contrast Media / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005263:Femoral Artery / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007260:Infusion Pumps; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D008297:Male; D008991:Monitoring, Physiologic; D015588:Observer Variation; D011134:Polysaccharides / Q000008:administration & dosage; D013997:Time Factors; D018608:Ultrasonography, Doppler / Q000379:methods*; D018615:Ultrasonography, Doppler, Color; D018616:Ultrasonography, Doppler, Duplex; D018617:Ultrasonography, Doppler, Pulsed; D014743:Videotape Recording
chemical_list: D003287:Contrast Media; D011134:Polysaccharides; C059891:SHU 508