How accurate is SPECT scanning 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

Answer

Without surprise, clinically validated SPECT scan studies showing differences between patients with Alzheimer disease and control subjects reveal high sensitivities and specificities of 80-90%. [51]

In one study, investigators compared patients from a dementia clinic with a community sample of control subjects using quantitative SPECT scanning and reported a 63% sensitivity and an 87% specificity. Alzheimer disease was defined in the study as temporal lobe perfusion more than 2 standard deviations below control values.

Holman et al found that bilateral temporoparietal hypoperfusion had a positive predictive value of 82% for Alzheimer disease. [52] Using inhaled xenon-133 (133 Xe) and injected technetium-99m [99mTc] hexamethylpropyleneamine oxime, researchers reported a sensitivity of 76% and a specificity of 73%, with a positive predictive value of 92% and a negative predictive value of 57%. [53] These studies may assist in the early and late diagnosis of Alzheimer disease and with the differential diagnosis of dementias.


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