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Published on: December 28, 2013
Comparison between PET template-based method and MRI-based method for cortical quantification of florbetapir (AV-45)
L Saint-Aubert1, F Nemmi, P Péran
1Inserm, imagerie cérébrale et handicaps neurologiques UMR 825, Centre Hospitalier Universitaire de Toulouse, Pavillon Baudot CHU Purpan lace Dr Baylac, 31059, Toulouse, France, laure.saint-aubert@inserm.fr.
Purpose:
Florbetapir (AV-45) has been shown to be a reliable tool for assessing in vivo amyloid load in patients with Alzheimer's disease from the early stages. However, nonspecific white matter binding has been reported in healthy subjects as well as in patients with Alzheimer's disease. To avoid this issue, cortical quantification might increase the reliability of AV-45 PET analyses. In this study, we compared two quantification methods for AV-45 binding, a classical method relying on PET template registration (route 1), and a MRI-based method (route 2) for cortical quantification.
Methods:
We recruited 22 patients at the prodromal stage of Alzheimer's disease and 17 matched controls. AV-45 binding was assessed using both methods, and target-to-cerebellum mean global standard uptake values (SUVr) were obtained for each of them, together with SUVr in specific regions of interest. Quantification using the two routes was compared between the clinical groups (intragroup comparison), and between groups for each route (intergroup comparison). Discriminant analysis was performed.
Results:
In the intragroup comparison, differences in uptake values were observed between route 1 and route 2 in both groups. In the intergroup comparison, AV-45 uptake was higher in patients than controls in all regions of interest using both methods, but the effect size of this difference was larger using route 2. In the discriminant analysis, route 2 showed a higher specificity (94.1 % versus 70.6 %), despite a lower sensitivity (77.3 % versus 86.4 %), and D-prime values were higher for route 2.
Conclusion:
These findings suggest that, although both quantification methods enabled patients at early stages of Alzheimer's disease to be well discriminated from controls, PET template-based quantification seems adequate for clinical use, while the MRI-based cortical quantification method led to greater intergroup differences and may be more suitable for use in current clinical research.
Insights
Comparing two methods for florbetapir (AV-45) PET imaging in Alzheimer's disease, MRI-based cortical quantification showed greater differences between patients and controls. This method may be more suitable for clinical research than standard PET template registration.
Area of Science:
- Neuroimaging
- Alzheimer's Disease Research
- Biomarker Quantification
Background:
- Florbetapir (AV-45) PET is used to assess amyloid plaque burden in Alzheimer's disease (AD).
- Nonspecific white matter binding can affect the reliability of AV-45 PET analyses.
- Cortical quantification methods may improve the accuracy of AV-45 binding assessment.
Purpose of the Study:
- To compare the reliability of two AV-45 quantification methods: PET template registration (route 1) and MRI-based cortical quantification (route 2).
- To evaluate the effectiveness of each method in discriminating between early-stage Alzheimer's disease patients and healthy controls.
Main Methods:
- Recruited 22 prodromal AD patients and 17 healthy controls.
- Assessed AV-45 binding using both PET template registration and MRI-based cortical quantification.
- Compared quantification results between groups and within groups using discriminant analysis.
Main Results:
- Both methods differentiated between AD patients and controls.
- MRI-based quantification (route 2) showed larger effect sizes for intergroup differences.
- Route 2 demonstrated higher specificity (94.1%) but lower sensitivity (77.3%) compared to route 1 (70.6% specificity, 86.4% sensitivity).
- Discriminant analysis yielded higher D-prime values for route 2.
Conclusions:
- Both quantification methods can distinguish early AD patients from controls.
- PET template-based quantification is adequate for clinical use.
- MRI-based cortical quantification offers greater intergroup discrimination and is potentially more suitable for clinical research.
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