title: Transcranial sonography and [18F]fluorodeoxyglucose positron emission tomography for the differential diagnosis of parkinsonism: a head-to-head comparison.
abstract: OBJECTIVE
  Brain imaging with positron emission tomography using [(18) F]fluorodeoxyglucose (FDG-PET) and transcranial B-mode sonography (TCS) improves the differential diagnosis of parkinsonism. The diagnostic merits of these approaches in identifying and differentiating atypical parkinsonian syndromes (APS) are compared.
  
  
  METHODS
  Data were included from 36 patients with clinically suspected APS who underwent PET and TCS. FDG-PET scans were analyzed by visual assessment (including voxel-based statistical maps) of a priori defined disease-specific metabolic patterns. Sonographers achieved diagnoses according to pre-defined criteria for echogenicities of the substantia nigra and lenticular nucleus, and third ventricle diameter. Patients with APS were identified and allocated to the subgroups multiple system atrophy (MSA), progressive supranuclear palsy (PSP) or corticobasal degeneration (CBD).
  
  
  RESULTS
  After a median follow-up period of 9 months, the final clinical diagnoses (reference standard) were Parkinson's disease, n = 15; MSA, n = 9; PSP, n = 7; and CBD, n = 5 (n = 21 APS in total). Six patients (4 APS) showed an insufficient bone window for TCS. In the remaining 30 patients, sensitivity/specificity for diagnosing APS were 82%/100% and 82%/85% for FDG-PET and TCS, respectively. Diagnostic accuracies did not differ between FDG-PET (90%) and TCS (83%; P = 0.69). Likewise, overall accuracy of subgroup classification (non-APS, MSA, PSP and CBD) did not differ between modalities (FDG-PET 87% and TCS 83%; P = 1.00).
  
  
  CONCLUSIONS
  FDG-PET and TCS show comparable accuracies for differential diagnosis of neurodegenerative parkinsonism. This preliminary study supports the use of TCS and warrants further prospective validation.
authors.affiliation: Department of Neurology, University Hospital Freiburg, Freiburg, Germany; Department of Psychiatry and Psychotherapy, University Hospital Freiburg, Freiburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Hellwig
authors.forename: M
authors.initials: M
authors.lastname: Reinhard
authors.forename: F
authors.initials: F
authors.lastname: Amtage
authors.forename: B
authors.initials: B
authors.lastname: Guschlbauer
authors.forename: R
authors.initials: R
authors.lastname: Buchert
authors.forename: O
authors.initials: O
authors.lastname: Tüscher
authors.forename: C
authors.initials: C
authors.lastname: Weiller
authors.forename: W D
authors.initials: WD
authors.lastname: Niesen
authors.forename: P T
authors.initials: PT
authors.lastname: Meyer
mesh_terms: D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000175:diagnosis* / Q000000981:diagnostic imaging; D020734:Parkinsonian Disorders / Q000175:diagnosis* / Q000000981:diagnostic imaging; D011877:Radionuclide Imaging; D012680:Sensitivity and Specificity; D013494:Supranuclear Palsy, Progressive / Q000175:diagnosis* / Q000000981:diagnostic imaging; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D019788:Fluorodeoxyglucose F18
keywords: atypical parkinsonian syndrome; parkinsonism; positron emission tomography; transcranial sonography