A comparison of 99mTc-exametazime and 123I-FP-CIT SPECT imaging in the differential diagnosis of Alzheimer's disease and dementia with Lewy bodies

Int Psychogeriatr. 2008 Dec;20(6):1124-40. doi: 10.1017/S1041610208007709. Epub 2008 Aug 27.


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.

Conclusion: Diagnostic accuracy was superior with 123I-FP-CIT compared to 99mTc-exametazime in the differentiation of DLB from AD.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alzheimer Disease / diagnostic imaging*
  • Alzheimer Disease / metabolism
  • Control Groups
  • Diagnosis, Differential
  • Dopamine / metabolism
  • Female
  • Humans
  • Iodine Radioisotopes
  • Lewy Body Disease / diagnostic imaging*
  • Lewy Body Disease / metabolism
  • Male
  • Neurofibrillary Tangles / diagnostic imaging
  • Occipital Lobe / blood supply
  • Occipital Lobe / diagnostic imaging*
  • ROC Curve
  • Regional Blood Flow
  • Sensitivity and Specificity
  • Technetium Tc 99m Exametazime*
  • Temporal Lobe / blood supply
  • Temporal Lobe / diagnostic imaging
  • Temporal Lobe / metabolism
  • Tomography, Emission-Computed, Single-Photon / methods*
  • Tomography, Emission-Computed, Single-Photon / statistics & numerical data
  • Tropanes*


  • Iodine Radioisotopes
  • Tropanes
  • 2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane
  • Technetium Tc 99m Exametazime
  • Dopamine