Iterative delay correction improves breath-hold cerebrovascular reactivity mapping in clinical populations.
4 affiliations
- 1Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States.
- 2Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL, United States.
- 3Department of Brain Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.
- 4Imperial College Healthcare NHS Trust, London, United Kingdom.
Abstract
Cerebrovascular reactivity (CVR), the ability of cerebral blood vessels to dilate or constrict in response to a vasoactive stimulus, is an important measure of cerebrovascular health. Accurate CVR estimation requires accounting for the time required for the vasoactive stimulus to reach each brain region and the time it takes for local arterioles to modulate cerebral blood flow. The temporal search range used to calculate this spatially varying offset can substantially impact CVR estimates, and the appropriate search range may vary across populations, acquisition protocols, and even brain regions. Here, we present an iterative approach for automatically determining the appropriate maximum shift, using breath-hold fMRI data acquired in a cohort of stroke survivors. This approach selectively expands the delay search range only for voxels with estimated delays at the boundary (i.e., near the minimum or maximum shift) until the estimated delay is no longer at the boundary or a predefined value is reached. In the context of stroke, among voxels initially at the boundary, this approach significantly increased the number of voxels with statistically significant CVR (i.e., having a relationship between end-tidal CO₂ and the BOLD signal that is unlikely to be due to random chance). It also resulted in CVR polarity reversals in voxels originally at the early-response boundary and amplified negative CVR values in voxels originally at the late-response boundary, suggesting that using an iterative maximum shift can critically impact CVR interpretation. This approach is broadly applicable beyond stroke, but careful parameter tuning is required, as illustrated by our demonstration of the parameter tuning process for a participant with Moyamoya disease. Together, these findings suggest that iterative delay correction allows for improved CVR assessments in clinical populations.
Related
- Cerebrovascular Reactivity to Hypoxic and Hypercapnic Gas Challenges Using 7T BOLD fMRI
- Understanding cerebral autoregulation and cerebrovascular reactivity: mechanistic perspectives and clinical insights from TBI.
- HLA-II Expression Marks Activated and Clonally Expanded CD8+ T Cells and Improves Tumor-Reactivity Prediction Across Human Cancers
- Characterization of chemoresistant cell populations improves risk stratification and therapy prediction in pediatric acute myeloid leukemia
- A 515,579-Genome Reference Panel Improves Rare-Variant Imputation Across Multiple Underrepresented Populations
BibTeX
@article{clements2026iterative,
title = {{Iterative delay correction improves breath-hold cerebrovascular reactivity mapping in clinical populations.}},
author = {Rebecca G Clements and Fatemeh Geranmayeh and Niamh V Parkinson and Molly G Bright},
journal = {Imaging neuroscience (Cambridge, Mass.)},
year = {2026},
month = oct,
doi = {10.1162/imag.a.1386},
url = {https://europepmc.org/article/MED/42835949},
note = {CC BY},
}
RIS
TY - JOUR
TI - Iterative delay correction improves breath-hold cerebrovascular reactivity mapping in clinical populations.
AU - Rebecca G Clements
AU - Fatemeh Geranmayeh
AU - Niamh V Parkinson
AU - Molly G Bright
PY - 2026
DA - 2026/10/01
JO - Imaging neuroscience (Cambridge, Mass.)
DO - 10.1162/imag.a.1386
UR - https://europepmc.org/article/MED/42835949
AB - Cerebrovascular reactivity (CVR), the ability of cerebral blood vessels to dilate or constrict in response to a vasoactive stimulus, is an important measure of cerebrovascular health. Accurate CVR estimation requires accounting for the time required for the vasoactive stimulus to reach each brain region and the time it takes for local arterioles to modulate cerebral blood flow. The temporal search range used to calculate this spatially varying offset can substantially impact CVR estimates, and the appropriate search range may vary across populations, acquisition protocols, and even brain regions. Here, we present an iterative approach for automatically determining the appropriate maximum shift, using breath-hold fMRI data acquired in a cohort of stroke survivors. This approach selectively expands the delay search range only for voxels with estimated delays at the boundary (i.e., near the minimum or maximum shift) until the estimated delay is no longer at the boundary or a predefined value is reached. In the context of stroke, among voxels initially at the boundary, this approach significantly increased the number of voxels with statistically significant CVR (i.e., having a relationship between end-tidal CO₂ and the BOLD signal that is unlikely to be due to random chance). It also resulted in CVR polarity reversals in voxels originally at the early-response boundary and amplified negative CVR values in voxels originally at the late-response boundary, suggesting that using an iterative maximum shift can critically impact CVR interpretation. This approach is broadly applicable beyond stroke, but careful parameter tuning is required, as illustrated by our demonstration of the parameter tuning process for a participant with Moyamoya disease. Together, these findings suggest that iterative delay correction allows for improved CVR assessments in clinical populations.
SN - 2837-6056
ER -