title: A comparison of 99mTc-exametazime and 123I-FP-CIT SPECT imaging in the differential diagnosis of Alzheimer's disease and dementia with Lewy bodies.
abstract: BACKGROUND
  The aim of this study is to investigate the diagnostic value of perfusion 99mTc-exametazime single photon emission computed tomography (SPECT) in the diagnosis of dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) in comparison with dopaminergic 123I-2beta-carbomethoxy-3beta-(4-iodophenyl)-n-(3-fluoropropyl) nortropane (FP-CIT) SPECT imaging.
  
  
  METHODS
  Subjects underwent 99mTc-exametazime scanning (39 controls, 36 AD, 30 DLB) and 123I-FP-CIT scanning (33 controls, 33 AD, 28 DLB). For each scan, five raters performed visual assessments blind to clinical diagnosis on selected transverse 99mTc-exametazime images in standard stereotactic space. Diagnostic accuracy of 99mTc-exametazime was compared to 123I-FP-CIT results for the clinically relevant subgroups AD and DLB using receiver operating characteristic (ROC) curve analysis.
  
  
  RESULTS
  Inter-rater agreement for categorizing uptake was "moderate" (mean kappa = 0.53) for 99mTc-exametazime and "excellent" (mean kappa = 0.88) for 123I-FP-CIT. For AD and DLB, consensus rating matched clinical diagnosis in 56% of cases using 99mTc-exametazime and 84% using 123I-FP-CIT. In distinguishing AD from DLB, ROC analysis revealed superior diagnostic accuracy with 123I-FP-CIT (ROC curve area 0.83, sensitivity 78.6%, specificity 87.9%) compared to occipital 99mTc-exametazime (ROC curve area 0.64, sensitivity 64.3%, specificity 63.6%) p = 0.03.
  
  
  CONCLUSIONS
  Diagnostic accuracy was superior with 123I-FP-CIT compared to 99mTc-exametazime in the differentiation of DLB from AD.
authors.affiliation: Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, UK. s.j.colloby@ncl.ac.uk
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Colloby
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Firbank
authors.forename: Sanjeet
authors.initials: S
authors.lastname: Pakrasi
authors.forename: Jim J
authors.initials: JJ
authors.lastname: Lloyd
authors.forename: Ian
authors.initials: I
authors.lastname: Driver
authors.forename: Ian G
authors.initials: IG
authors.lastname: McKeith
authors.forename: E David
authors.initials: ED
authors.lastname: Williams
authors.forename: John T
authors.initials: JT
authors.lastname: O'Brien