title: Is R2* a new MRI biomarker for the progression of Parkinson's disease? A longitudinal follow-up.
abstract: OBJECTIVE
  To study changes of iron content in basal ganglia in Parkinson's disease (PD) through a three-year longitudinal follow-up of the effective transverse relaxation rate R2*, a validated MRI marker of brain iron content which can be rapidly measured under clinical conditions.
  
  
  METHODS
  Twenty-seven PD patients and 26 controls were investigated by a first MRI (t0). Longitudinal analysis was conducted among the 18 controls and 14 PD patients who underwent a second MRI (t1) 3 years after. The imaging protocol consisted in 6 gradient echo images obtained at different echo-times for mapping R2*. Quantitative exploration of basal ganglia was performed by measuring the variation of R2* [R2*(t1) - R2*(t0)] in several regions of interest.
  
  
  RESULTS
  During the three-year evolution of PD, R2* increased in Substantia nigra (SN) (by 10.2% in pars compacta, p = 0.001, and 8.1% in pars reticulata, p = 0.013) and in the caudal putamen (11.4%, p = 0.011), without significant change in controls. Furthermore, we showed a positive correlation between the variation of R2* and the worsening of motor symptoms of PD (p = 0.028).
  
  
  CONCLUSIONS
  Significant variation of R2* was longitudinally observed in the SN and caudal putamen of patients with PD evolving over a three-year period, emphasizing its interest as a biomarker of disease progression. Our results suggest that R2* MRI follow-up could be an interesting tool for individual assessment of neurodegeneration due to PD, and also be useful for testing the efficiency of disease-modifying treatments.
authors.affiliation: CHU Clermont-Ferrand, Service de Neurologie A, Clermont-Ferrand, France. mulla@chu-clermontferrand.fr
authors.forename: Miguel
authors.initials: M
authors.lastname: Ulla
authors.forename: Jean Marie
authors.initials: JM
authors.lastname: Bonny
authors.forename: Lemlih
authors.initials: L
authors.lastname: Ouchchane
authors.forename: Isabelle
authors.initials: I
authors.lastname: Rieu
authors.forename: Beatrice
authors.initials: B
authors.lastname: Claise
authors.forename: Franck
authors.initials: F
authors.lastname: Durif
mesh_terms: D000368:Aged; D001479:Basal Ganglia / Q000378:metabolism / Q000473:pathology*; D015415:Biomarkers / Q000378:metabolism; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007501:Iron / Q000378:metabolism*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D011699:Putamen / Q000378:metabolism / Q000473:pathology*; D012154:Reticular Formation / Q000378:metabolism / Q000473:pathology*; D013378:Substantia Nigra / Q000378:metabolism / Q000473:pathology*
chemical_list: D015415:Biomarkers; D007501:Iron