title: Can FLAIR hyperintense vessel (FHV) signs be influenced by varying MR parameters and flow velocities? A flow phantom analysis.
abstract: BACKGROUND
  Fluid-attenuated inversion recovery (FLAIR) hyperintense vessels (FHVs) have been used to assess leptomeningeal collateral flow in acute ischemic stroke. However, prior FHVs studies showed inconsistent results, which may be ascribable to different magnetic resonance (MR) parameters used.
  
  
  OBJECTIVE
  To evaluate whether FHVs could be influenced by varying MR parameters and flow velocities, using a flow phantom.
  
  
  METHODS
  A total of 512 sets of FLAIRs were performed with varying parameters and flow velocities, using a flow phantom. Flow phantom was manufactured with 3.5% agarose solution, an 8-mm inner diameter silicone tube and non-pulsatile pump. Varying MR parameters were repetition time (TR)/inversion time (TI), echo time (TE), flip angle (FA) of refocusing pulse, and periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER). The signal intensity of flow were measured and regarded as the degree of FHVs. Simple and multiple linear regression analyses were applied to evaluate the association between the degree of FHVs and varying MR parameters as well as flow velocities.
  
  
  RESULTS
  On univariate analysis, PROPELLER technique (R(2 )= 0.448) demonstrated strongest correlation with the degree of FHV, followed by flow velocities (R(2 )= 0.204), FA (R(2 )= 0.126), and TE (R(2 )= 0.031), whereas TR/TI showed no significant correlations. On multivariate analysis, TE, FA, PROPELLER technique, and flow velocities were independent factors influencing the degree of FHVs (<0.001).
  
  
  CONCLUSIONS
  Flow velocities, FA of refocusing pulse, TE, and PROPELLER technique significantly affected the degree of FHVs. Optimized MR parameters should be used consistently in future studies, which may provide more reliable results.
authors.affiliation: Department of Radiology, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sung Jun
authors.initials: SJ
authors.lastname: Ahn
authors.affiliation: Department of Neurology, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Kyung-Yul
authors.initials: KY
authors.lastname: Lee
authors.affiliation: Department of Radiology, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Ahn
authors.affiliation: Department of Medical Engineering, Yonsei University College of Medicine, Seoul, Republic of Korea.
authors.forename: Hwal
authors.initials: H
authors.lastname: Suh
authors.affiliation: Department of Radiology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Bum-Soo
authors.initials: BS
authors.lastname: Kim
authors.affiliation: Department of Radiology, Yonsei University College of Medicine, Seoul, Republic of Korea slee@yuhs.ac lee.seungkoo@gmail.com.
authors.forename: Seung-Koo
authors.initials: SK
authors.lastname: Lee
mesh_terms: D002545:Brain Ischemia / Q000175:diagnosis; D002536:Cerebral Arteries / Q000473:pathology; D003287:Contrast Media; D004867:Equipment Design; D018056:Hemorheology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D018810:Magnetic Resonance Angiography / Q000379:methods*; D019047:Phantoms, Imaging; D020521:Stroke / Q000175:diagnosis
chemical_list: D003287:Contrast Media
keywords: FLAIR; Stroke; collateral circulation; flow phantom; magnetic resonance imaging (MRI)