title: Cerebral Peduncle Angle: An Objective Criterion for Assessing Progressive Supranuclear Palsy Richardson Syndrome.
abstract: OBJECTIVE
  Several criteria for time-consuming volumetric measurements of progressive supranuclear palsy Richardson syndrome subtype (PSP-RS) have been proposed. These often require image reconstruction in different planes for proper assessment. The purpose of this study was to evaluate the cerebral peduncle angle as a simple and reproducible measure of midbrain atrophy in patients with PSP-RS.
  
  
  METHODS
  The records of 15 patients with PSP-RS were retrospectively identified. The records of 31 age-matched healthy control subjects, 15 patients with multiple-system atrophy, and 22 patients with Parkinson disease were included for comparison. Two neuroradiologists individually assessed these studies for midbrain atrophy by evaluating the cerebral peduncle angle, that is, the angle between the two cerebral peduncles.
  
  
  RESULTS
  The cerebral peduncle angle measurements were 62.1° (SD, 6.8°) in PSP-RS patients, 51.2° (SD, 10.1°) in healthy control subjects, 55.7° (SD, 11.6°) in patients with multiple-system atrophy, and 53.7° (SD, 8.5°) in patients with Parkinson disease. A statistically significant difference was found in the cerebral peduncle angle measurements (observer 1, p = 0.015; observer 2, p = 0.004) between the PSP-RS patients and the other subgroups. Bland-Altman analysis showed a bias of 0.6° (95% limits of agreement, 6.9°, -5.8°), and intraobserver variability analysis showed a bias of 0.5° (4.1°, -3°).
  
  
  CONCLUSIONS
  The cerebral peduncle angle is a simple, easy-to-calculate, and reproducible measure of midbrain atrophy. It is a useful criterion for differentiating patients with PSP-RS from healthy persons and from patients with multiple-system atrophy or Parkinson disease.
authors.affiliation: 1 Department of Radiology, New York University School of Medicine, 660 First Ave, 7th Fl, New York, NY 10016.
authors.forename: Girish M
authors.initials: GM
authors.lastname: Fatterpekar
authors.affiliation: 1 Department of Radiology, New York University School of Medicine, 660 First Ave, 7th Fl, New York, NY 10016.
authors.forename: August
authors.initials: A
authors.lastname: Dietrich
authors.affiliation: 2 Department of Neurology and Psychiatry, Neuroradiology Unit, IRCCS Neuromed, Pozilli (IS), Sapienza University of Rome, Rome, Italy.
authors.forename: Patrizia
authors.initials: P
authors.lastname: Pantano
authors.affiliation: 3 Department of Radiology, Azienda Ospedaliero Universitaria, di Cagliari, Polo di Monserrato, Cagliari, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Saba
authors.affiliation: 1 Department of Radiology, New York University School of Medicine, 660 First Ave, 7th Fl, New York, NY 10016.
authors.forename: Edmond A
authors.initials: EA
authors.lastname: Knopp
authors.affiliation: 2 Department of Neurology and Psychiatry, Neuroradiology Unit, IRCCS Neuromed, Pozilli (IS), Sapienza University of Rome, Rome, Italy.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Piattella
authors.affiliation: 1 Department of Radiology, New York University School of Medicine, 660 First Ave, 7th Fl, New York, NY 10016.|2 Department of Neurology and Psychiatry, Neuroradiology Unit, IRCCS Neuromed, Pozilli (IS), Sapienza University of Rome, Rome, Italy.
authors.forename: Eytan
authors.initials: E
authors.lastname: Raz
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D065850:Cerebral Peduncle / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy; D010641:Phenotype; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013494:Supranuclear Palsy, Progressive / Q000473:pathology*
keywords: Richardson syndrome; atrophy; cerebral peduncle; neurodegenerative disease; progressive supranuclear palsy