title: The value of GRE, ADC and routine MRI in distinguishing Parkinsonian disorders.
abstract: OBJECTIVE
  To study different radiological signs and sequences including apparent diffusion coefficient (ADC) and gradient echo (GRE) to differentiate degenerative parkinsonian syndromes.
  
  
  BACKGROUND
  Multiple system atrophy (MSA), Parkinson's disease (PD), progressive supranuclear palsy (PSP) and corticobasal degeneration (CbD) differ in the pattern of neurodegeneration and cellular damage. Measuring the ADC, GRE sequences for paramagnetic substances and simple anatomical assessments have been reported individually to assist in separating some of these disorders, but have not been compared.
  
  
  METHODS
  brain MRIs from May 2002 to February 2008 were retrospectively evaluated by raters blinded to the clinical diagnosis for predefined MRI signs on T1, T2 and GRE sequences. ADC values were quantitatively measured. Medical records were objectively analyzed using standard clinical criteria for different parkinsonian syndromes.
  
  
  RESULTS
  195 cases comprising of 61 PD, 15 MSA-P, 7 MSA-C, 21 PSP, 6 Corticobasal syndrome, 21 not fitting criteria and 64 controls were evaluated. 73% of patients with MSA-P had hypointensity of the putamen (compared to the pallidum) on GRE. The specificity of this sign to diagnose MSA-P was 90% versus PD and 76% versus PSP. When GRE hypointensity was combined with atrophy of the putamen the specificity improved to 98% (versus PD) and 95% (versus PSP) without altering the sensitivity. The ADC values were significantly higher in the middle cerebellar peduncle in cases with MSA-C versus controls, PD and PSP (p<0.001).
  
  
  CONCLUSIONS
  The combination of hypointensity and atrophy of the putamen on GRE is useful in differentiating MSA-P from other parkinsonian syndromes.
authors.affiliation: Movement Disorders Center and the Edmond J. Safra Program in Parkinson's Disease, Division of Neurology, University Health Network, University of Toronto, Canada Department of Neurology, Jaslok Hospital and Research Institute, Mumbai, India.
authors.forename: Pettarusp M
authors.initials: PM
authors.lastname: Wadia
authors.forename: Peter
authors.initials: P
authors.lastname: Howard
authors.forename: Manuel Q
authors.initials: MQ
authors.lastname: Ribeirro
authors.forename: Jennifer
authors.initials: J
authors.lastname: Robblee
authors.forename: Abena
authors.initials: A
authors.lastname: Asante
authors.forename: David J
authors.initials: DJ
authors.lastname: Mikulis
authors.forename: Anthony E
authors.initials: AE
authors.lastname: Lang
mesh_terms: D000368:Aged; D001921:Brain / Q000473:pathology*; D001931:Brain Mapping; D038524:Diffusion Magnetic Resonance Imaging; D017352:Echo-Planar Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000175:diagnosis; D010300:Parkinson Disease / Q000175:diagnosis*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013494:Supranuclear Palsy, Progressive / Q000175:diagnosis