title: Olfactory function in patients with multiple sclerosis: a diffusion tensor imaging study.
abstract: BACKGROUND
  Previous research has shown that multiple sclerosis (MS) patients can develop olfactory disturbances.
  
  
  OBJECTIVE
  The purpose of our study was to investigate how olfactory function in MS patients correlates with cerebral magnetic resonance imaging (MRI) including diffusion tensor imaging (DTI).
  
  
  METHODS
  Olfactory performance was tested in 30 MS patients and 30 controls to determine odour threshold (T), odour discrimination (D), and odour identification (I) summarised in the TDI score. The lesion load (number and total volume of lesions) was measured on proton-density (PD)- and T2-weighted images of the olfactory brain and the total brain. Fractional anisotropy (FA) of the lesions and the surrounding normal-appearing brain tissue (NABT) was quantified using DTI.
  
  
  RESULTS
  The median FA of white matter lesions was 0.29 and was on average 11.1% lower than in the surrounding NABT. The normalised TDI score and the normalised I subscore were significantly poorer in the MS group compared to controls (p<0.0001), while the T and D subscores were similar in both groups. The median FA of lesions in the olfactory brain correlated inversely with the decreased I subscore (p=0.001). There was also a strong correlation between the TDI score and the Expanded Disability Status Scale (EDSS) (p=0.001).
  
  
  CONCLUSIONS
  A strong inverse relationship between decreased odour identification ability of MS patients and FA values in the olfactory brain indicates that the reduction in I is more strongly affected by lesions in areas with high FA values, i.e., with an increased amount of affected white matter tracts.
authors.affiliation: Department of Radiology, Charité, Universitätsmedizin Berlin, Campus Benjamin Franklin, 12200 Berlin, Germany. katharina.erb@charite.de
authors.forename: Katharina
authors.initials: K
authors.lastname: Erb
authors.forename: Georg
authors.initials: G
authors.lastname: Bohner
authors.forename: Lutz
authors.initials: L
authors.lastname: Harms
authors.forename: Oender
authors.initials: O
authors.lastname: Goektas
authors.forename: Franca
authors.initials: F
authors.lastname: Fleiner
authors.forename: Esther
authors.initials: E
authors.lastname: Dommes
authors.forename: Felix Alexander
authors.initials: FA
authors.lastname: Schmidt
authors.forename: Bettina
authors.initials: B
authors.lastname: Dahlslett
authors.forename: Lutz
authors.initials: L
authors.lastname: Lüdemann
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000175:diagnosis* / Q000503:physiopathology*; D059906:Neuroimaging / Q000379:methods; D000857:Olfaction Disorders / Q000175:diagnosis / Q000503:physiopathology; D012903:Smell / Q000502:physiology*