62 year old man with progressive memory difficulties. He said he will frequently go into a room and not remember why he was there, and has difficulty remembering names and phone numbers.
This coronal T2 weighted image of the brain shows scattered T2 hyperintensities in the periventricular and subcortical white matter, a nonspecific finding. There is asymmetric appearance of the hippocampi (asterisks), which sit on the parahippocampal gyri in the medial temporal lobes. Equivocal prominence of the right greater than left uncal recesses of the temporal horns (arrows) and the ambient cisterns (arrowheads) is also noted.
The patient underwent further imaging with FDG PET:
PET imaging shows hypometabolism of bilateral temporal and parietal lobes, and minimally in the right frontal lobe. (Seen as areas of decreased orange-red using this color gradient.) The sensorimotor cortex and occipital lobes are relatively spared.
These findings can be further appreciated using FDG surface maps.
Surface Metabolism (top) and Hypometabolism (bottom) Maps
This patient was diagnosed with Alzheimer’s Disease.
Anatomic imaging findings in Alzheimer’s Disease include atrophy of medial temporal lobe structures especially the hippocampus. Functional imaging with FDG PET typically demonstrates hypometabolism of the parietal and temporal lobes (and later the frontal lobes), with relative sparing of the sensorimotor cortex and occipital lobes. Classic areas of involvement include the precuneus and posterior cingulate gyrus (seen at the medial aspect of the parietal lobes on surface maps), which has been shown as a sensitive predictor of progression from mild cognitive impairment to Alzheimer’s Disease. Nordberg A, et al. Nat Rev Neurol 2010;6:78-87.
