Abstract W P368: Longitudinal Change in fMRI Blood Oxygen Level Dependent Signal in Cerebral Amyloid Angiopathy
Introduction: Previous cross-sectional studies show that cerebral amyloid angiopathy (CAA) is associated with reduced blood oxygen level dependent (BOLD) signal change in response to a visual task, and that this reduction is due to impaired vascular reactivity. However, there are no data on the rate at which the BOLD signal changes over time in CAA. We hypothesized that fMRI activation would decline in CAA, representing progressively impaired vasoreactivity, and this decline would be associated with increased white matter hyperintensity (WMH) volume.
Methods: fMRI BOLD amplitude was measured in response to a visual task (alternating checkerboard pattern) at study entry and 1-year follow-up for 18 patients with probable CAA by Boston criteria, and 15 healthy controls. fMRI data were matched to a canonical BOLD signal using a general linear model resulting in z-statistic images with a significance threshold of p<0.05 using FSL. The amplitude of the BOLD signal percent change from baseline was measured in the 200 most active voxels in the primary visual cortex. WMH were identified on fluid attenuated inversion recovery (FLAIR) images and the volume was measured using Quantomo software (Cybertrials Inc, Canada).
Results: BOLD amplitude was lower at follow-up than baseline in CAA, but the difference was not significant (mean change -0.14±0.55, p=0.30). Mean BOLD amplitude was similar at baseline and follow-up in controls (mean change 0.20±0.49, p=0.14). The difference in rate of change over time between CAA and controls was borderline significant (p=0.04). fMRI was lower at follow-up than baseline in 11/18 CAA compared to 4/15 controls (p=0.08). In CAA patients, WMH increased over time (median 1.44 mL interquartile range -0.22 to 9.70mL, p=0.01). However, BOLD amplitude change and WMH change were not related (r=-0.01, p=0.96).
Discussion: Although we did not see significant fMRI BOLD signal reduction from baseline to 1 year in CAA, we did see a difference in change over time between CAA and controls, consistent with our hypothesis that impaired vasoreactivity is a feature of CAA. Studies with larger numbers of patients, or longer duration of follow-up, are needed to more precisely determine the rate of change over time in reduction of fMRI BOLD amplitude in CAA.
Author Disclosures: A.R. Switzer: None. C.R. McCreary: None. R. Frayne: None. B.G. Goodyear: None. E.E. Smith: None.
- © 2014 by American Heart Association, Inc.