title: Measuring brain stem and cerebellar damage in parkinsonian syndromes using diffusion tensor MRI.
abstract: OBJECTIVE
  To use diffusion tensor MRI to quantify and compare degeneration of the pons and cerebellar peduncles in multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and Parkinson disease (PD) and to relate changes in diffusion measures to clinical features and localized atrophy.
  
  
  METHODS
  We used a region-of-interest approach to measure changes in fractional anisotropy and mean diffusivity in the middle cerebellar peduncles, decussation of the superior cerebellar peduncles, and pons in 17 patients with MSA, 17 with PSP, 12 with PD, and 12 healthy volunteers. We also evaluated atrophy of the cerebellar peduncles and pons on T2-weighted magnetic resonance images in patients with MSA and PSP.
  
  
  RESULTS
  In MSA, fractional anisotropy was markedly reduced in the middle cerebellar peduncles, and mean diffusivity increased both here and in the pons compared with other groups, whereas in PSP, mean diffusivity was strikingly increased in the decussation of superior cerebellar peduncles. Cerebellar ataxia was related to mean diffusivity in the middle cerebellar peduncles (r = 0.71, p = 0.001) and pons (r = 0.60, p = 0.01) in MSA. Diffusion measures were related to localized atrophy in both MSA and PSP.
  
  
  CONCLUSIONS
  Diffusion tensor MRI can be used to quantify neurodegenerative processes in different brain stem and cerebellar structures in multiple system atrophy and progressive supranuclear palsy during life, and may have diagnostic value. Larger studies of early, undifferentiated parkinsonian syndromes are indicated to provide estimates of the relative diagnostic value of diffusion measures, atrophy measures, and visual assessment of scans.
authors.affiliation: King's College London, Institute of Psychiatry, MRC Centre for Neurodegeneration, Department of Clinical Neuroscience, London, UK.
authors.forename: C R V
authors.initials: CR
authors.lastname: Blain
authors.forename: G J
authors.initials: GJ
authors.lastname: Barker
authors.forename: J M
authors.initials: JM
authors.lastname: Jarosz
authors.forename: N A
authors.initials: NA
authors.lastname: Coyle
authors.forename: S
authors.initials: S
authors.lastname: Landau
authors.forename: R G
authors.initials: RG
authors.lastname: Brown
authors.forename: K R
authors.initials: KR
authors.lastname: Chaudhuri
authors.forename: A
authors.initials: A
authors.lastname: Simmons
authors.forename: D K
authors.initials: DK
authors.lastname: Jones
authors.forename: S C R
authors.initials: SC
authors.lastname: Williams
authors.forename: P N
authors.initials: PN
authors.lastname: Leigh
mesh_terms: D000368:Aged; D001284:Atrophy / Q000473:pathology; D001933:Brain Stem / Q000473:pathology; D002526:Cerebellar Diseases / Q000150:complications / Q000473:pathology*; D002531:Cerebellum / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000473:pathology*; D011149:Pons / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013577:Syndrome