How accurate is MRI in 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

MRI findings of hippocampal atrophy are highly associated with Alzheimer disease, but the specificity is not well established. [41] Studies have shown that in patients with Alzheimer disease and moderate dementia, hippocampal volumes permitted correct classification in 85% of patients. [42] In patients with Alzheimer disease and mild dementia, sensitivity was 77%, and specificity, 80%. [43] Hippocampal volume was the best discriminator, although a number of medical temporal-lobe structures were studied, including the amygdala and the parahippocampal gyrus.

Hippocampal atrophy appears to be a feature of vascular disease (multi-infarct dementia) and Parkinson disease, even in patients with Parkinson disease without dementia. Hippocampal and entorhinal cortical atrophy are features of frontotemporal dementia, but they do not appear to be as profound as atrophy is in Alzheimer disease. [44]


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