LEARN NUCLEAR MEDICINE
Neurology · Case 05
Read the history, inspect the study, then reveal the teaching.
IMAGE PLACEHOLDER · Diagnostic study
Original study · Companion image placeholders
Clinical history
73 year old male presents with history of forgetfulness and mood swings concerning for dementia. FDG PET scan is performed to determine if a particular dementia pattern can be identified.
Read the images before opening the teaching panel below.
Alzheimer’s Dementia
Imaging Findings
There is decreased metabolic activity within the bilateral posterior temporoparietal cortex. Additionally, there is preservation of metabolic activity within the sensorimotor cortex and occipital cortex.
Essential Facts
In Alzheimer’s dementia, intracerebral plaques and neurofibrillary tangles are related to the abnormal deposition of amyloid and tau proteins.
Plaques destroy neurons via cell membrane lysis.
Tangles fill the cytoplasm of axons and dendrites leading to impaired glucose transport.
In the case of Alzheimer’s dementia, PET studies may demonstrate regionally decreased glucose metabolism as a result of decreased glucose transport and neuronal loss.
The most common pattern is typically posterior temporal parietal hypometabolism which may initially be asymmetric. There is preservation of the sensory motor cortex. Late stage disease may involve the bilateral frontal lobes.
References
“Central Nervous System.” Essentials of Nuclear Medicine Imaging, by Fred A. Mettler and Milton J. Guiberteau, Elsevier Saunders, 2012, pp. 71–97.