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Reduced-order modeling and analysis of dynamic cerebral autoregulation via diffusion maps
K R M Dos Santos1, M I Katsidoniotaki2, E C Miller3
1Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, Minneapolis, MN, United States of America.
Physiological Measurement
|March 24, 2023
Summary
A new diffusion map technique reliably assesses dynamic cerebral autoregulation (DCA) function. This method effectively identifies impaired DCA in internal carotid artery stenosis patients and outperforms transfer function analysis, especially with missing data.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Data Science
Background:
- Dynamic cerebral autoregulation (DCA) is crucial for maintaining stable cerebral blood flow.
- Impaired DCA is associated with neurological conditions like internal carotid artery (ICA) stenosis.
- Existing analysis methods may have limitations in accuracy and robustness, particularly with incomplete data.
Purpose of the Study:
- To develop a novel, data-driven, and parsimonious modeling technique for DCA analysis using diffusion maps.
- To assess the reliability and sensitivity of this diffusion map technique in distinguishing between healthy and impaired DCA.
- To compare the performance of diffusion maps against traditional transfer function analysis (TFA), including scenarios with missing data.
Main Methods:
- A state-space model of DCA dynamics was established using arterial blood pressure and cerebral blood flow velocity.
- Diffusion maps were employed for dimensionality reduction via eigenvalue analysis of a Markov matrix.
- The ratio of the two most significant eigenvalues was used to classify DCA as active or hypoactive, indicating healthy or impaired function, respectively.
Main Results:
- The diffusion map technique demonstrated an 81% sensitivity in detecting side-to-side differences in DCA for ICA stenosis patients, outperforming TFA (71%).
- Both methods identified differences between the affected and healthy sides, but diffusion maps also detected a difference between the unaffected side and the healthy group.
- Diffusion maps showed superior performance compared to TFA when dealing with missing data.
Conclusions:
- The eigenvalue ratio derived from diffusion maps serves as a reliable and robust biomarker for assessing intrinsic DCA activity.
- This technique can effectively differentiate between healthy and impaired DCA function.
- Diffusion maps offer a promising advancement in the analysis of cerebral autoregulation, especially in complex clinical scenarios.

