Longitudinal evaluation of early Alzheimer's disease using brain perfusion SPECT

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Alzheimer's disease (AD) is a progressive neurodegenerative disorder.
• Early detection of AD is crucial for timely intervention and management.
• Changes in regional cerebral blood flow (rCBF) are indicative of early neuropathological processes in AD.

Purpose of the Study:

• To determine the initial abnormalities in rCBF in early Alzheimer's disease (AD).
• To investigate longitudinal changes in rCBF in early AD.
• To utilize statistical parametric mapping (SPM) for analyzing rCBF alterations.

Main Methods:

• (99m)Tc-ethyl cysteinate dimer SPECT was used to measure rCBF in 32 patients with mild cognitive impairment and 45 healthy volunteers.
• Patients were diagnosed with AD during a follow-up of at least 2 years, with repeat SPECT scans at a mean interval of 15 months.
• Statistical parametric mapping (SPM) was applied to analyze both absolute and adjusted rCBF parametric maps.

Main Results:

• Baseline SPECT revealed significantly reduced adjusted rCBF bilaterally in the posterior cingulate gyri and precunei of AD patients compared to controls.
• Follow-up studies showed further reduction in adjusted rCBF in the left hippocampus and parahippocampal gyrus.
• Longitudinal analysis indicated a progressive decline in absolute rCBF across extensive areas of the cerebral association cortex.

Conclusions:

• SPM analysis identified a distinct early AD pattern of selective rCBF decrease and longitudinal decline.
• These rCBF alterations may be missed by conventional region-of-interest techniques.
• The observed changes in rCBF are closely linked to the underlying pathophysiological processes of Alzheimer's disease.