Iterative analysis of cerebrovascular reactivity dynamic response by temporal decomposition

Abstract

ObjectiveTo improve quantitative cerebrovascular reactivity (CVR) measurements and CO 2 arrival times, we present an iterative analysis capable of decomposing different temporal components of the dynamic carbon dioxide‐ Blood Oxygen‐Level Dependent (CO 2‐BOLD) relationship.Experimental DesignDecomposition of the dynamic parameters included a redefinition of the voxel‐wise CO 2 arrival time, and a separation from the vascular response to a stepwise increase in CO 2 (Delay to signal Plateau – DTP) and a decrease in CO 2 (Delay to signal Baseline –DTB). Twenty‐five (normal) datasets, obtained from BOLD MRI combined with a standardized pseudo‐square wave CO 2 change, were co‐registered to generate reference atlases for the aforementioned dynamic processes to score the voxel‐by‐voxel deviation probability from normal range. This analysis is further illustrated in two subjects with unilateral carotid artery occlusion using these reference atlases.Principal ObservationsWe have found that our redefined CO 2 arrival time resulted in the best data fit. Additionally, excluding both dynamic BOLD phases (DTP and DTB) resulted in a static CVR, that is maximal response, defined as CVR calculated only over a normocapnic and hypercapnic calibrated plateau.ConclusionDecomposition and novel iterative modeling of different temporal components of the dynamic CO 2‐BOLD relationship improves quantitative CVR measurements.

BOLD cerebrovascular reactivity as a novel marker for crossed cerebellar diaschisis

“…BOLD asymmetry was also studied by using a hyperoxic gas challenge to show significant asymmetric cerebellar hemispheric BOLD signal changes in a small cohort of participants with acute large-volume middle cerebral artery strokes. 26 Using a novel carbon dioxide application technique 27 and improved BOLD-CVR analysis methods, 16 we were able to generate high-resolution quantitative cerebellar BOLD-CVR maps. With a cutoff point of BOLD-CVR cerebellar asymmetry index of 6, CCD was detected with a sensitivity of 0.91 and a specificity of 0.81.…”

“…The CVR calculations were done according to a previously described and validated method. 16 In short, after temporal shifting for optimal physiologic correlation of the 2 time series, CVR was calculated from the slope of a linear least square fit of the BOLD signal time course to the carbon dioxide time series over the range of the first baseline of 100 seconds, the 80 seconds step portion of the protocol, and the second baseline of 100 seconds on a voxel-by-voxel basis. CVR was defined as the percentage BOLD signal change per mm Hg carbon dioxide change.…”

“…From BOLD in combination with a carbon dioxide challenge, cerebrovascular reactivity (CVR) can be quantitatively mapped for the entire brain, including the cerebellum. [15][16][17] BOLD-CVR is defined as the percentage BOLD signal change per mm Hg carbon dioxide and is frequently used to measure supratentorial cerebrovascular reserve capacity. 18 Although BOLD signal changes can be seen in parallel with changes in cerebral blood flow, 19 the BOLD signal primarily depends on changes in deoxyhemoglobin-not cerebral blood flow changes directly.…”

Crossed Cerebellar Diaschisis in Patients with Diffuse Glioma Is Associated with Impaired Supratentorial Cerebrovascular Reactivity and Worse Clinical Outcome

“…Extra BOLD fMRI volumes (40 volumes) were acquired to allow for potential temporal shift. A more extensive description of the BOLD-CVR calculation pipeline can be found in our previous work [ 5 ].…”

“…Blood oxygenation level–dependent fMRI (BOLD)-CVR with a standardized carbon dioxide (CO 2 ) stimulus [ 5 , 6 ] is a contemporary technique for investigating CVR impairment in patients with diffuse glioma [ 7 , 8 ]. It has also shown its utility in accurately detecting CCD, albeit this has been mostly investigated in cerebrovascular patients [ 3 , 9 ].…”