title: [Distinguishing between occluded and low-flow vessels with PROPELLER DWI sequence: a phantom study].
abstract: OBJECTIVE
  To evaluate the ability of periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted imaging (PROPELLER DWI) to distinguish between vessel occlusion and slow flow.
  
  
  METHODS
  Using a flow phantom with various velocities (1.37 to 11.1 cm/s), the signal-intensity ratios of the phantom, with the intensity of no flow as baseline, were measured using the following imaging sequences: PROPELLER DWI, spin-echo T1-weighted imaging (SE T1WI), fast-spin-echo T2-weighted imaging (FSE T2WI), two-dimensional phase-contrast imaging (2D PC), and two-dimensional time-of-flight imaging (2D TOF). The b-factor of PROPELLER DWI was varied from 0 to 1000 s/mm(2). The velocity encoding of 2D PC was varied from 2 to 30 cm/s.
  
  
  RESULTS
  At the lowest flow velocity (1.37 cm/s) , the signal-intensity ratio was 0.0075 for PROPELLER DWI (b-factor=1000 s/mm(2)), 1.8 for SE T1WI, 0.67 for FSE T2WI, 11 for 2D PC (velocity encoding=2 cm/s), and 1.4 for 2D TOF. The signal-intensity ratio was smallest for PROPELLER DWI, even when the reciprocals of the signal-intensity ratio of 2D PC or 2D TOF were considered.
  
  
  CONCLUSIONS
  The results indicate that PROPELLER DWI provides the best signal intensity-ratio between vessel occlusion and slow flow. Although DWI with single-shot echo-planar imaging (EPI) or multi-shot EPI may have similarly high sensitivity for slow flow, these sequences do not have high spatial resolution or robustness to susceptibility artifacts. PROPELLER DWI would be a better choice for distinguishing between occluded and low-velocity arteries in the skull base or parasellar regions.
authors.affiliation: Department of Radiological Technology, University of Tokyo Hospital.
authors.forename: Masami
authors.initials: M
authors.lastname: Goto
authors.forename: Shigeki
authors.initials: S
authors.lastname: Aoki
authors.forename: Naoto
authors.initials: N
authors.lastname: Hayashi
authors.forename: Harushi
authors.initials: H
authors.lastname: Mori
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Kenji
authors.initials: K
authors.lastname: Ino
authors.forename: Yoshirou
authors.initials: Y
authors.lastname: Satake
authors.forename: Katuji
authors.initials: K
authors.lastname: Nishida
authors.forename: Haruo
authors.initials: H
authors.lastname: Sato
authors.forename: Kyouhito
authors.initials: K
authors.lastname: Iida
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mima
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
mesh_terms: D001783:Blood Flow Velocity; D002560:Cerebrovascular Circulation / Q000502:physiology*; D002561:Cerebrovascular Disorders / Q000175:diagnosis / Q000503:physiopathology*; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D019047:Phantoms, Imaging