Background: Cerebral amyloid angiopathy (CAA) causes vascular cognitive impairment, possibly due to ischemic lesions that are caused by impaired cerebral blood flow. Cerebral microinfarcts (CMIs) are small ischemic lesions that are found in CAA patients at autopsy.
Hypothesis: Cortical CMIs can be detected on in vivo 3T MR images in CAA and will correlate with markers of CAA-related vascular brain injury and cognitive function.
Methods: We analysed data from CAA cases and neurologically healthy controls participating in the Functional Assessment of Vascular Reactivity (FAVR) study. All participants underwent a standardized clinical, neuropsychological and 3T MR assessment. Cortical CMIs were rated according to standardized criteria, by a single rater blinded to clinical information.
Results: There were 36 CAA patients (mean age 73.0±9.0 years) and 22 healthy controls (69.0±8.3 years). Cortical CMIs were found in significantly more patients with CAA (50%) (median number: 1, range: 1-9) than in healthy controls (18%) (p=0.02). In CAA, patients with cortical CMIs had higher white matter hyperintensity volumes (median 29.5 mL vs 13.0 mL, p=0.04) and cerebral microbleed counts (median 28 vs 5.5, p=0.049). CAA patients with cortical CMIs also showed lower occipital fMRI activation (median BOLD change 1.97% vs 2.57%, r=0.24, p=0.15) and worse memory performance (mean z-score -0.60 vs -0.05, p=0.12), although both effects were non-significant. No significant association of cortical CMIs with age, sex or vascular risk factors was found.
Conclusions: Cortical CMIs are frequently detected on 3T MRI in CAA. They relate to well-established ischemic and hemorrhagic MRI markers of CAA. Therefore in vivo cortical CMIs can be regarded as a new marker of CAA disease severity. Additional, larger studies are needed to determine the relationship between CMI and clinical outcomes in CAA.