title: Transcranial Sonography and DaTSCAN in Early Stage Parkinson's Disease and Essential Tremor.
abstract: The diagnosis of Parkinson's disease (PD) can sometimes be a challenge in the early stages of the disease. Both transcranial sonography (TCS) and DaTSCAN are recommended as auxiliary examinations for the differential diagnosis of PD; however, only few data exist regarding their diagnostic accuracy in the early stage of PD and essential tremor (ET).
  
  
  
  We evaluated patients with clinically suspected diagnosis of PD at early stages (Hoehn and Yahr ≤2) or ET. All patients underwent DaTSCAN and TCS with a maximum interval of 6 months. Final diagnosis was established after 1-year follow-up.
  
  
  
  From the 63 patients recruited, 3 were excluded due to transcranial insonability and 2 for uncertain clinical diagnosis. The final clinical diagnosis was ET in 44.8% and PD in 55.2%. Compared to clinical diagnosis of PD, TCS had a sensitivity of 87.5% and specificity of 96.2%; DaTSCAN sensitivity was 84.4% and specificity was 96.2%. Both diagnostic tests demonstrated a substantial level of agreement (Cohen's kappa coefficient: 0.83, 95% CI 0.68-0.97, p < 0.001).
  
  
  
  TCS and DaTSCAN have similar diagnostic accuracy for the diagnosis of early stage PD versus ET.
authors.affiliation: Department of Neurology, Centro Hospitalar e Universitário de Coimbra, University of Coimbra, Coimbra, Portugal.
authors.forename: Joana
authors.initials: J
authors.lastname: Jesus-Ribeiro
authors.forename: António
authors.initials: A
authors.lastname: Freire
authors.forename: João
authors.initials: J
authors.lastname: Sargento-Freitas
authors.forename: Mário
authors.initials: M
authors.lastname: Sousa
authors.forename: Fernando
authors.initials: F
authors.lastname: Silva
authors.forename: Fradique
authors.initials: F
authors.lastname: Moreira
authors.forename: Maria João
authors.initials: MJ
authors.lastname: Cunha
authors.forename: Uwe
authors.initials: U
authors.lastname: Walter
authors.forename: Cristina
authors.initials: C
authors.lastname: Januário
mesh_terms: D003937:Diagnosis, Differential; D020329:Essential Tremor / Q000000981:diagnostic imaging; D006801:Humans; D009662:Nortropanes; D010300:Parkinson Disease / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*
chemical_list: D009662:Nortropanes; C519528:ioflupane