Aging Effect, Reproducibility, and Test-Retest Reliability of a New Cerebral Amyloid Angiopathy MRI Severity Marker-Cerebrovascular Reactivity to Visual Stimulation.

BACKGROUND

Decreased cerebrovascular reactivity, measured as changes in blood-oxygen-level-dependent (BOLD) signal, is a potential new cerebral amyloid angiopathy (CAA) severity marker. Before clinical application, the effect of aging on BOLD parameters, and reproducibility and test-retest reliability of these parameters should be assessed.

PURPOSE

Assess the effect of healthy aging on cerebrovascular reactivity (BOLD amplitude, time to peak, and time to baseline). And determine reproducibility and test-retest reliability of these parameters.

STUDY TYPE

Prospective-observational.

POPULATION

Eighty-six healthy adults (mean age 56 years, 55% female), 10 presymptomatic D-CAA mutation carriers (mean age 34 years, 70% female), and 10 symptomatic D-CAA mutation carriers (mean age 54 years, 70% female).

FIELD STRENGTH/SEQUENCE: 3-T, three-dimensional (3D) T1-weighted MRI and gradient echo BOLD fMRI.

ASSESSMENT

To assess test-retest reliability of BOLD parameters, i.e. BOLD amplitude, time to peak, and time to baseline, BOLD fMRI scans were repeated three times immediately after each other, in both controls and mutation carriers. To assess reproducibility, BOLD fMRI scans were repeated with a 3-week interval for each subject.

STATISTICAL TESTS

Linear regression analyses and two-way mixed absolute agreement intra-class correlation approach.

RESULTS

Healthy aging was associated with decreased BOLD amplitude (β = -0.711) and prolonged time to baseline (β = 0.236) in the visual cortex after visual stimulation Reproducibility of BOLD amplitude was excellent (ICC 0.940) in the subgroup of healthy adults. Test-retest reliability for BOLD amplitude was excellent in healthy adults (ICC 0.856-0.910) and presymptomatic D-CAA mutation carriers (ICC 0.959-0.981). In symptomatic D-CAA mutation carriers, test-retest reliability was poor for all parameters (ICCs < 0.5).

DATA CONCLUSION

Healthy aging is associated with decreased cerebrovascular reactivity, measured by changes in BOLD response to visual stimulation. The BOLD amplitude appears to be a robust measurement in healthy adults and presymptomatic D-CAA mutation carriers, but not in symptomatic D-CAA mutation carriers.