title: Gray matter contamination in arterial spin labeling white matter perfusion measurements in patients with dementia.
abstract: BACKGROUND
  White matter (WM) perfusion measurements with arterial spin labeling can be severely contaminated by gray matter (GM) perfusion signal, especially in the elderly. The current study investigates the spatial extent of GM contamination by comparing perfusion signal measured in the WM with signal measured outside the brain.
  
  
  METHODS
  Four minute 3T pseudo-continuous arterial spin labeling scans were performed in 41 elderly subjects with cognitive impairment. Outward and inward geodesic distance maps were created, based on dilations and erosions of GM and WM masks. For all outward and inward geodesic distances, the mean CBF was calculated and compared.
  
  
  RESULTS
  GM contamination was mainly found in the first 3 subcortical WM voxels and had only minor influence on the deep WM signal (distances 4 to 7 voxels). Perfusion signal in the WM was significantly higher than perfusion signal outside the brain, indicating the presence of WM signal.
  
  
  CONCLUSIONS
  These findings indicate that WM perfusion signal can be measured unaffected by GM contamination in elderly patients with cognitive impairment. GM contamination can be avoided by the erosion of WM masks, removing subcortical WM voxels from the analysis. These results should be taken into account when exploring the use of WM perfusion as micro-vascular biomarker.
authors.affiliation: Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Henri J M M
authors.initials: HJ
authors.lastname: Mutsaerts
authors.affiliation: Department of Neurology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Edo
authors.initials: E
authors.lastname: Richard
authors.affiliation: Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Dennis F R
authors.initials: DF
authors.lastname: Heijtel
authors.affiliation: C.J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Matthias J P
authors.initials: MJ
authors.lastname: van Osch
authors.affiliation: Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Charles B L M
authors.initials: CB
authors.lastname: Majoie
authors.affiliation: Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Aart J
authors.initials: AJ
authors.lastname: Nederveen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003704:Dementia / Q000175:diagnosis*; D005260:Female; D066128:Gray Matter / Q000098:blood supply* / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008609:Mental Status Schedule; D011673:Pulsatile Flow / Q000502:physiology; D013113:Spin Labels; D066127:White Matter / Q000098:blood supply* / Q000473:pathology
chemical_list: D013113:Spin Labels
keywords: ASL, arterial spin labeling; Arterial spin labeling; CBF, cerebral blood flow; CSF, cerebrospinal fluid; Dementia; GM, gray matter; Gray matter contamination; PSF, point spread function; PV, partial volume; Partial volume; SNR, signal-to-noise ratio; WM, white matter; White matter perfusion