What are the preferred imaging modalities for the diagnosis of Alzheimer disease?

Updated: Apr 12, 2018
  • Author: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS; Chief Editor: L Gill Naul, MD  more...
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Answer

Answer

Structural imaging, preferably with MRI when possible and computed tomography (CT) when not, should be obtained as a first-tier approach. MRI can be considered the preferred neuroimaging examination for Alzheimer disease because it allows for accurate measurement of the 3-dimensional (3D) volume of brain structures, especially the size of the hippocampus and related regions. Second-tier imaging with molecular methods, preferably with fluorodeoxyglucose PET (or single-photon emission CT if PET is unavailable) can provide more diagnostic specificity. [7]

Neuroimaging is widely believed to be generally useful for excluding reversible causes of dementia syndrome, such as normal-pressure hydrocephalus, brain tumors, and subdural hematoma, and for excluding other likely causes of dementia, such as cerebrovascular disease. [3]

The practice parameters for the diagnosis and evaluation of dementia, as published by the American Academy of Neurology (AAN), consider structural brain imaging to be optimal. [8, 9] Nonenhanced CT scanning and MRI are the appropriate imaging methods. [7] The AAN suggests that neuroimaging may be most useful in patients with dementia characterized by an early onset or an unusual course.


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