title: Longitudinal magnetization transfer imaging in mild to severe Alzheimer disease.
abstract: OBJECTIVE
  MTI has been proposed as a sensitive technique for studying microstructural brain tissue changes in patients with AD, but the course of these changes over time is largely unknown. We therefore used a placebo-controlled study of memantine to follow the evolution of tissue damage in AD by means of MTR measurements and investigated how MTR changes were related to brain atrophy and cognition.
  
  
  METHODS
  Twenty-eight patients (76.5 ± 5.8 years) with mild to moderate AD underwent MTI, brain volume measurements, and cognitive testing at baseline and after 6 and 12 months. Nineteen healthy individuals (73.3 ± 3.2 years) served as controls. MTI was performed with a 2-minute protocol that was optimized for an enhanced MT effect and reduced motion sensitivity. Global and regional MTR measurements served as correlations with brain volumes and the MMSE score.
  
  
  RESULTS
  AD patients had significantly lower global MTR values than controls, and showed a consistent and significant MTR reduction in all regions investigated over a period of 12 months. These MTR changes were paralleled by a brain tissue loss of 2.2% per year. Associations between MTR and cognition were found for the hippocampus, putamen, and thalamus, and were more pronounced in the left hemisphere.
  
  
  CONCLUSIONS
  MTI in AD allows the assessment of ongoing global and regional brain damage independent of atrophy, and therefore appears to be a valuable marker for disease-related tissue changes.
authors.affiliation: Department of Neurology, Medical University of Graz, Graz, Austria. stefan.ropele@medunigraz.at
authors.forename: S
authors.initials: S
authors.lastname: Ropele
authors.forename: R
authors.initials: R
authors.lastname: Schmidt
authors.forename: C
authors.initials: C
authors.lastname: Enzinger
authors.forename: M
authors.initials: M
authors.lastname: Windisch
authors.forename: N P
authors.initials: NP
authors.lastname: Martinez
authors.forename: F
authors.initials: F
authors.lastname: Fazekas
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000473:pathology*; D001921:Brain / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity