title: The midbrain to pons ratio: a simple and specific MRI sign of progressive supranuclear palsy.
abstract: OBJECTIVE
  MRI-based measurements used to diagnose progressive supranuclear palsy (PSP) typically lack pathologic verification and are not easy to use routinely. We aimed to develop in histologically proven disease a simple measure of the midbrain and pons on sagittal MRI to identify PSP.
  
  
  METHODS
  Measurements of the midbrain and pontine base on midsagittal T1-weighted MRI were performed in confirmed PSP (n = 12), Parkinson disease (n = 2), and multiple system atrophy (MSA) (n = 7), and in controls (n = 8). Using receiver operating characteristic curve analysis, cutoff values were applied to a clinically diagnosed cohort of 62 subjects that included PSP (n = 21), Parkinson disease (n = 10), MSA (n = 10), and controls (n = 21).
  
  
  RESULTS
  The mean midbrain measurement of 8.1 mm was reduced in PSP (p < 0.001) with reduction in the midbrain to pons ratio (PSP smaller than MSA; p < 0.001). In controls, the mean midbrain ratio was approximately two-thirds of the pontine base, in PSP it was <52%, and in MSA the ratio was greater than two-thirds. A midbrain measurement of <9.35 mm and ratio of 0.52 had 100% specificity for PSP. In the clinically defined group, 19 of 21 PSP cases (90.5%) had a midbrain measurement of <9.35 mm.
  
  
  CONCLUSIONS
  We have developed a simple and reliable measurement in pathologically confirmed disease based on the topography of atrophy in PSP with high sensitivity and specificity that may be a useful tool in the clinic.
authors.affiliation: Sara Koe PSP Research Centre, Rita Lila Weston Institute for Neurology Studies and Queen Square Brain Bank, Department of Molecular Neurosciences, UCL Institute of Neurology, London, UK. l.massey@ion.ucl.ac.uk
authors.forename: Luke A
authors.initials: LA
authors.lastname: Massey
authors.forename: Hans R
authors.initials: HR
authors.lastname: Jäger
authors.forename: Dominic C
authors.initials: DC
authors.lastname: Paviour
authors.forename: Sean S
authors.initials: SS
authors.lastname: O'Sullivan
authors.forename: Helen
authors.initials: H
authors.lastname: Ling
authors.forename: David R
authors.initials: DR
authors.lastname: Williams
authors.forename: Constantinos
authors.initials: C
authors.lastname: Kallis
authors.forename: Janice
authors.initials: J
authors.lastname: Holton
authors.forename: Tamas
authors.initials: T
authors.lastname: Revesz
authors.forename: David J
authors.initials: DJ
authors.lastname: Burn
authors.forename: Tarek
authors.initials: T
authors.lastname: Yousry
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lees
authors.forename: Nick C
authors.initials: NC
authors.lastname: Fox
authors.forename: Caroline
authors.initials: C
authors.lastname: Micallef
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards*; D008297:Male; D008636:Mesencephalon / Q000473:pathology*; D008875:Middle Aged; D011149:Pons / Q000473:pathology*; D013494:Supranuclear Palsy, Progressive / Q000175:diagnosis* / Q000453:epidemiology