title: Correction for Susceptibility Distortions Increases the Performance of Arterial Spin Labeling in Patients with Cerebrovascular Disease.
abstract: Arterial spin labeling (ASL) is an MRI technique to measure cerebral blood flow (CBF) without the need of exogenous contrast agents and is thus a promising alternative to the clinical standard dynamic susceptibility-weighted contrast-enhanced (DSC) perfusion imaging. Latest international guidelines encourage its application in the clinical setting. However, susceptibility-induced image distortions impair ASL with fast readout modules (eg Echo Planar Imaging, EPI; gradient and spin echo, GRASE). In the present study, we investigated the benefit of a distortion correction for ASL compared to DSC.
  
  
  
  A pulsed ASL (PASL) sequence combined with a 3D-GRASE readout at multiple inflow times (multi-TI) was used and was corrected for susceptibility distortions using a FMRIB Software Library (FSL) implemented tool TOPUP. We performed qualitative (three expert raters) and quantitative (volume of interest [VOI]-based) comparisons of ASL and DSC imaging in 13 patients with chronic steno-occlusive disease.
  
  
  
  In the qualitative analysis, distortion correction of the images led to a strong increase in diagnostic precision of ASL compared to DSC in the anterior cerebral artery (ACA) perfusion territory, where the susceptibility artifact was most pronounced (specificity 8% vs. 75%). In the quantitative analysis, the correlation between ASL and DSC values increased for all perfusion territories with the best improvement for the ACA territory (for anterior, middle and posterior cerebral artery: ACA: rho -0.22 vs. 0.71; MCA: rho 0.58 vs. 0.76; PCA: rho 0.58 vs. 0.63).
  
  
  
  We showed that susceptibility distortion correction strongly improves the comparability of multi-TI ASL 3D-GRASE to DSC in steno-occlusive disease. We suggest it to be implemented in ASL postprocessing routines.
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.|Department of Neurology, Charité-Universtitätsmedizin, Berlin, Germany.
authors.forename: Vince I
authors.initials: VI
authors.lastname: Madai
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.
authors.forename: Steve Z
authors.initials: SZ
authors.lastname: Martin
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.|Fraunhofer MEVIS, Bremen, Germany.
authors.forename: Federico C
authors.initials: FC
authors.lastname: von Samson-Himmelstjerna
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.
authors.forename: Cornelius X
authors.initials: CX
authors.lastname: Herzig
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.|Department of Neurology, Charité-Universtitätsmedizin, Berlin, Germany.
authors.forename: Matthias A
authors.initials: MA
authors.lastname: Mutke
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.
authors.forename: Carla N
authors.initials: CN
authors.lastname: Wood
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.
authors.forename: Thoralf
authors.initials: T
authors.lastname: Thamm
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.|Department of Neurology, Charité-Universtitätsmedizin, Berlin, Germany.
authors.forename: Sarah
authors.initials: S
authors.lastname: Zweynert
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Bauer
authors.affiliation: Berlin Center for Advanced Neuroimaging (BCAN), Berlin, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Hetzer
authors.affiliation: Fraunhofer MEVIS, Bremen, Germany.|University Bremen, Bremen, Germany.|mediri GmbH, Heidelberg, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Günther
authors.affiliation: Center for Stroke Research Berlin (CSB), Charité-Universitätsmedizin, Berlin, Germany.|Department of Neurology, Charité-Universtitätsmedizin, Berlin, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Sobesky
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D020244:Infarction, Middle Cerebral Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013113:Spin Labels; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D013113:Spin Labels
keywords: ASL; Arterial spin labeling; DSC; MRI; TOPUP; steno-occlusive disease