Case of the Month: December, 2011 Page 4

Answer: A. 1:3

Discussion Points:

This case represents an example of Alzheimer Disease where there is discordant results between FDG-PET and volumetric MRI
In 2000, 4 million people were affected by Alzheimer Disease
With aging “baby boomer” population, total US prevalence expected to increase to 20 million by year 2025
Age is the greatest risk factor for AD, prevalence of AD over age 60 = 1:10,000 and over age 85 = 1:3
Pathologic diagnosis of AD demonstrates characteristic B-Amyloid plaques in extracellular spaces throughout cerebral cortex and neurofibrillary tangles within neurons of the hippocampus
FDG-PET can differentiate AD from other forms of dementia:
- Frontotemporal Dementia: decreased metabolism of frontal/temporal lobes
- Multi-infarct Dementia: discrete nonpaired foci of decreased metabolism
- Lewy-Body Disease: decreased metabolism includes occipital lobes
- NPH: enlarged lateral ventricles showing no activity
AD treatment with Acetylcholinesterase inhibitors and NMDA receptor antagonists may mildly increase cognition or delay deficits up to 9-12 months
Novel PET diagnostic imaging technique involving direct radiolabelled binding of amyloid plaques is currently in Phase 3 clinical trials with reported high sensitivity and specificity

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