Objective To evaluate visual assessment of [11C]PIB and [18F]FDDNP PET images as potential supportive diagnostic markers for Alzheimer's disease (AD).
Methods Twenty-one AD patients and 20 controls were included. Parametric [11C]PIB and [18F]FDDNP global binding potential (BPND) images were visually rated as ‘AD’ or ‘normal.’ Data were compared with ratings of [18F]FDG PET images and MRI-derived medial temporal lobe atrophy (MTA) scores. Inter-rater agreement and agreement with clinical diagnosis were assessed for all imaging modalities. In addition, cut-off values for quantitative global [11C]PIB and [18F]FDDNP BPND were determined. Visual ratings were compared with dichotomised quantitative values.
Results Agreement between readers was excellent for [11C]PIB, [18F]FDDNP and MTA (Cohen kappa κ≥0.85) and moderate for [18F]FDG (κ=0.56). The highest sensitivity was found for [11C]PIB and [18F]FDG (both 1.0). The highest specificity was found for MTA (0.90) and [11C]PIB (0.85). [18F]FDDNP had the lowest sensitivity and specificity (0.67 and 0.53, respectively). The cut-off for quantitative [11C]PIB BPND was 0.54 (sensitivity and specificity both 0.95) and for [18F]FDDNP BPND 0.07 (sensitivity 0.80, specificity 0.73). Agreement between quantitative analyses and visual ratings was excellent for [11C]PIB (κ=0.85) and fair for [18F]FDDNP (κ=0.40).
Conclusion Visual assessment of [11C]PIB images was straightforward and accurate, showing promise as a supportive diagnostic marker for AD. Moreover, [11C]PIB showed the best combination of sensitivity and specificity. Visual assessment of [18F]FDDNP images was insufficient. The quantitative analysis of [18F]FDDNP data showed a considerably higher diagnostic value than the visual analysis.
- Alzheimer's disease
- PET, ligand studies
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Funding This work was financially supported by the Internationale Stichting Alzheimer Onderzoek (ISAO, grant 05512), and the American Health Assistance Foundation (AHAF, grant A2005-026).
Competing interests PS serves/has served as Associate Editor of the Journal of Neurology, Neurosurgery & Psychiatry.
Ethics approval Ethics approval was provided by the Medical Ethics Review Committee of the VU University Medical Centre Amsterdam.
Provenance and peer review Not commissioned; externally peer reviewed.