title: Central intraluminal saturation stripe on MR angiograms of curved vessels: simulation, phantom, and clinical analysis.
abstract: OBJECTIVE
  To investigate the appearance of reduced signal intensity in the center of blood vessels on magnetic resonance (MR) angiograms that can mimic intraluminal thrombus.
  
  
  METHODS
  Simulations and phantom studies were performed to analyze MR angiogram appearance distal to a pronounced curve.
  
  
  RESULTS
  Saturation effects substantially lower the signal strength in the center of the vessel relative to that at the vessel periphery. These effects appeared even though the flow was well ordered and laminar. In curved geometries, secondary flow patterns produced counter-rotating vortices, which moved the fastest-moving particles to the outside of the curve and folded the slow-moving particles to the center of the vessel.
  
  
  CONCLUSIONS
  Imaging parameter choices that reduce saturation, such as acquisition of a two-dimensional section transverse to the vessel and through the questionable region, effectively eliminate the central hypointensity effect in vivo.
authors.affiliation: Radiology Service, Veteran's Administration Medical Center, San Francisco, California 94121, USA.
authors.forename: D
authors.initials: D
authors.lastname: Saloner
authors.forename: R
authors.initials: R
authors.lastname: van Tyen
authors.forename: W P
authors.initials: WP
authors.lastname: Dillon
authors.forename: L D
authors.initials: LD
authors.lastname: Jou
authors.forename: S A
authors.initials: SA
authors.lastname: Berger
mesh_terms: D000328:Adult; D016477:Artifacts; D001783:Blood Flow Velocity; D001808:Blood Vessels / Q000033:anatomy & histology*; D002343:Carotid Artery, Internal / Q000033:anatomy & histology / Q000502:physiology; D003198:Computer Simulation; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging