title: Reduced perfusion in white matter lesions in multiple sclerosis.
abstract: OBJECTIVE
  To investigate dynamic susceptibility contrast (DSC) perfusion weighted imaging (PWI) in white matter lesions (WML) in patients with multiple sclerosis (MS), using automatically generated binary masks of brain tissue.
  
  
  BACKGROUND
  WML in MS have in some studies demonstrated perfusion abnormalities compared to normal appearing white matter (NAWM), however perfusion changes in WML in MS have in general not been well documented.
  
  
  METHODS
  DSC PWI was performed at 1.5 Tesla in 69 newly diagnosed MS patients. Parametric perfusion maps representing cerebral blood volume (CBV), cerebral blood flow (CBF) and mean transit time (MTT) were obtained. Binary masks of WML, white matter (WM) and grey matter (GM) were automatically generated and co-registered to the perfusion maps. The WML mask was manually edited and modified to correct for errors in the automatic lesion detection. Perfusion parameters were derived both from WML and NAWM using the manually modified WML mask, and using the original non-modified WML mask (with and without GM exclusion mask). Differences in perfusion measures between WML and NAWM were analyzed.
  
  
  RESULTS
  CBF was significantly lower (p<0.001) and MTT significantly higher (p<0.001) in WML compared to NAWM. CBV did not show significant difference between WML and NAWM. The non-modified WML mask gave similar results as manually modified WML mask if the GM exclusion mask was used in the analysis.
  
  
  CONCLUSIONS
  DSC PWI revealed lower CBF and higher MTT, consistent with reduced perfusion, in WML compared to NAWM in patients with early MS. Automatically generated binary masks are a promising tool in perfusion analysis of WML.
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway. Electronic address: piotr.sowa@medisin.uio.no.
authors.forename: Piotr
authors.initials: P
authors.lastname: Sowa
authors.affiliation: Intervention Center, Oslo University Hospital, Oslo, Norway; Department of Physics, University of Oslo, Oslo, Norway. Electronic address: atle.bjornerud@fys.uio.no.
authors.forename: Atle
authors.initials: A
authors.lastname: Bjørnerud
authors.affiliation: Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital, Oslo, Norway. Electronic address: g.o.nygaard@medisin.uio.no.
authors.forename: Gro O
authors.initials: GO
authors.lastname: Nygaard
authors.affiliation: Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden. Electronic address: soheil.damangir@ki.se.
authors.forename: Soheil
authors.initials: S
authors.lastname: Damangir
authors.affiliation: Department of Neurobiology, Care Sciences and Society, Karolinska Institute, Stockholm, Sweden. Electronic address: gabriela.spulber@ki.se.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Spulber
authors.affiliation: Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital, Oslo, Norway. Electronic address: uxelgu@ous-hf.no.
authors.forename: Elisabeth G
authors.initials: EG
authors.lastname: Celius
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway. Electronic address: pdue@ous-hf.no.
authors.forename: Paulina
authors.initials: P
authors.lastname: Due-Tønnessen
authors.affiliation: Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital, Oslo, Norway. Electronic address: h.f.harbo@medisin.uio.no.
authors.forename: Hanne F
authors.initials: HF
authors.lastname: Harbo
authors.affiliation: Department of Radiology and Nuclear Medicine, Oslo University Hospital, Oslo, Norway; Department of Life Sciences and Health, Oslo and Akershus University College of Applied Sciences, Oslo, Norway. Electronic address: mona.beyer@lyse.net.
authors.forename: Mona K
authors.initials: MK
authors.lastname: Beyer
mesh_terms: D000328:Adult; D002560:Cerebrovascular Circulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000473:pathology*; D066127:White Matter / Q000098:blood supply* / Q000473:pathology*; D055815:Young Adult
keywords: Binary mask; Dynamic susceptibility contrast; Magnetic resonance imaging; Multiple sclerosis; Perfusion weighted imaging