title: Fast 4D flow MRI intracranial segmentation and quantification in tortuous arteries.
abstract: OBJECTIVE
  To describe, validate, and implement a centerline processing scheme (CPS) for semiautomated segmentation and quantification in carotid siphons of healthy subjects. 4D flow MRI enables blood flow measurement in all major cerebral arteries with one scan. Clinical translational hurdles are time demanding postprocessing and user-dependence induced variability during analysis.
  
  
  METHODS
  A CPS for 4D flow data was developed to automatically separate cerebral artery trees. Flow parameters were quantified at planes along the centerline oriented perpendicular to the vessel path. At 3T, validation against 2D phase-contrast (PC) magnetic resonance imaging (MRI) and 4D flow manual processing was performed on an intracranial flow phantom for constant flow, while pulsatile flow validation was performed in the internal carotid artery (ICA) of 10 healthy volunteers. The CPS and 4D manual processing times were measured and compared. Flow and area measurements were also demonstrated along the length of the ICA siphon.
  
  
  RESULTS
  Phantom measurements for area and flow were highly correlated between the CPS and 2D measurements (area: R = 0.95, flow: R = 0.94), while in vivo waveforms were highly correlated (R = 0.93). Processing time was reduced by a factor of 4.6 compared with manual processing. Whole ICA measurements revealed a significantly decreased area in the most distal segment of the carotid siphon (P = 0.0017), with flow unchanged (P = 0.84).
  
  
  CONCLUSIONS
  This study exhibits fast semiautomated analysis of intracranial 4D flow MRI. Internal consistency was shown through flow conservation along the tortuous ICA siphon, which is typically difficult to assess.
authors.affiliation: Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, USA.|Department of Radiation Sciences, Umeå University, Umeå, Sweden.
authors.forename: Eric
authors.initials: E
authors.lastname: Schrauben
authors.affiliation: Department of Radiation Sciences, Umeå University, Umeå, Sweden.|Umeå Center for Functional Brain Imaging (UFBI), Umeå University, Umeå, Sweden.|Department of Radiology, University of Wisconsin - Madison, Madison, Wisconsin, USA.
authors.forename: Anders
authors.initials: A
authors.lastname: Wåhlin
authors.affiliation: Department of Radiation Sciences, Umeå University, Umeå, Sweden.|Center for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden.
authors.forename: Khalid
authors.initials: K
authors.lastname: Ambarki
authors.affiliation: Department of Radiation Sciences, Umeå University, Umeå, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Spaak
authors.affiliation: Department of Clinical Neuroscience, Umeå University, Umeå, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Malm
authors.affiliation: Department of Medical Physics, University of Wisconsin - Madison, Madison, Wisconsin, USA.|Department of Radiology, University of Wisconsin - Madison, Madison, Wisconsin, USA.
authors.forename: Oliver
authors.initials: O
authors.lastname: Wieben
authors.affiliation: Department of Radiation Sciences, Umeå University, Umeå, Sweden.|Center for Biomedical Engineering and Physics, Umeå University, Umeå, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Eklund
mesh_terms: D000328:Adult; D002339:Carotid Arteries / Q000002:abnormalities*; D002536:Cerebral Arteries / Q000002:abnormalities*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: 4D flow MRI; automated processing; segmentation; vascular
references.citation: J Physiol. 2003 Jul 15;550(Pt 2):575-83
references.pmid: 12766246
references.citation: Stroke. 1983 Mar-Apr;14(2):256-66
references.pmid: 6220490
references.citation: Stroke. 1996 Mar;27(3):486-9
references.pmid: 8610318
references.citation: Neurosurgery. 1996 Mar;38(3):425-32; discussion 432-3
references.pmid: 8837792
references.citation: AJNR Am J Neuroradiol. 2005 Apr;26(4):743-9
references.pmid: 15814915
references.citation: J Biopharm Stat. 2007;17(4):571-82
references.pmid: 17613642
references.citation: Magn Reson Med. 2008 Dec;60(6):1329-36
references.pmid: 19025882
references.citation: J Cardiovasc Magn Reson. 2011;13:55
references.pmid: 21970399
references.citation: Int J Comput Assist Radiol Surg. 2012 Mar;7(2):217-24
references.pmid: 21779767
references.citation: J Magn Reson Imaging. 2012 May;35(5):1055-62
references.pmid: 22170792
references.citation: J Magn Reson Imaging. 2012 Jun;35(6):1462-71
references.pmid: 22282344
references.citation: Magn Reson Med. 2012 Oct;68(4):1065-73
references.pmid: 22161650
references.citation: J Magn Reson Imaging. 2012 Nov;36(5):1015-36
references.pmid: 23090914
references.citation: Invest Ophthalmol Vis Sci. 2013 Apr;54(4):2738-45
references.pmid: 23518769
references.citation: AJNR Am J Neuroradiol. 2013 Sep;34(9):1740-5
references.pmid: 23493888