Alzheimer’s disease (AD) is the leading cause of dementia
worldwide and significantly impacts the essential functions of daily life and
social activities. Research on AD has found that its pathogenesis is related to
the extracellular accumulation of amyloid-beta (A) plaques and
intracellular neurofibrillary tangles in the cortical and limbic areas of the
human brain, as well as cerebrovascular factors. The detection of A or
tau can be performed using various probes and methodologies. However, these
modalities are expensive to implement and often require invasive procedures,
limiting accessibility on a large scale. While magnetic resonance imaging (MRI)
and computed tomography (CT) are generally used for morphological and structural
brain imaging, they show wide variability in their accuracy for the clinical
diagnosis of AD. Several novel imaging modalities have emerged as alternatives
that can accurately and vividly display the changes in blood flow and metabolism
in each brain area and enable physicians and researchers to gain insights into
the generation and progression of the cerebro-microvascular pathologies of AD. In
this review, we summarize the current knowledge on microvascular perfusion
imaging modalities and their application in AD, including MRI (dynamic
susceptibility contrast-MRI, arterial spin labeling-MRI), CT (cerebral CT
perfusion imaging), emission computed tomography (positron emission tomography
(PET), single-photon emission computed tomography (SPECT)), transcranial doppler
ultrasonography (TCD), and retinal microvascular imaging (optical coherence
tomography imaging, computer-assisted methods for evaluating retinal
vasculature).