A comparative study of signal processing techniques for non-invasive assessment of intracranial dynamics
A comparative study of signal processing techniques for non-invasive assessment of intracranial dynamics
The work within this thesis investigates non-invasive methods, and signal processing techniques, for the assessment of intracranial compliance in the human cranium.
A dynamic simulation, using a six compartment model, is programmed using Matlab's Simulink Toolbox, and is used to investigate changes to blood pressures and flows within the human cranium. The simulation indicated that changes to the resistances and compliances, resulted in phase and amplitude changes, leading to the proposition that if flows and pressures were measured, then changes to intracranial compliance could be estimated. The use of transcranial Doppler ultrasound, to measure middle cerebral artery (MCA) velocity, and a non-invasive pressure transducer to measure arterial blood pressure (ABP), enabled the predictions of the simulation to be realised. A series of volunteer experiments were carried out, under controlled conditions of inhaled CO2, to induce the effect of hypo- and hypercapnia, causing changes to the intracranial compliance.
Four signal processing methods were investigated, and compared, to determine the most appropriate technique for ease of presentation and interpretation. Cross correlation of MCA velocity with ABP, was developed, to determine the phase shift, with respect to changing pathology. The phase shift, or 'transit time' as it was referred to in the thesis, was found to correlate strongly with changes to intracranial compliance.
The above signal processing methods, applied to the analysis of non-invasive MCA velocity measurements, for the prediction of changes to intracranial compliance, are considered to be original contributions to knowledge. In particular the proposed method of presenting the 'transit time' and the 'frequency centroid', simultaneously, on a two-dimensional map, is not only original, but also potentially an improvement to the data presentation methods for intracranial parameters that are currently in use in neurological units.
University of Southampton
1999
Penson, Richard Peter
(1999)
A comparative study of signal processing techniques for non-invasive assessment of intracranial dynamics.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The work within this thesis investigates non-invasive methods, and signal processing techniques, for the assessment of intracranial compliance in the human cranium.
A dynamic simulation, using a six compartment model, is programmed using Matlab's Simulink Toolbox, and is used to investigate changes to blood pressures and flows within the human cranium. The simulation indicated that changes to the resistances and compliances, resulted in phase and amplitude changes, leading to the proposition that if flows and pressures were measured, then changes to intracranial compliance could be estimated. The use of transcranial Doppler ultrasound, to measure middle cerebral artery (MCA) velocity, and a non-invasive pressure transducer to measure arterial blood pressure (ABP), enabled the predictions of the simulation to be realised. A series of volunteer experiments were carried out, under controlled conditions of inhaled CO2, to induce the effect of hypo- and hypercapnia, causing changes to the intracranial compliance.
Four signal processing methods were investigated, and compared, to determine the most appropriate technique for ease of presentation and interpretation. Cross correlation of MCA velocity with ABP, was developed, to determine the phase shift, with respect to changing pathology. The phase shift, or 'transit time' as it was referred to in the thesis, was found to correlate strongly with changes to intracranial compliance.
The above signal processing methods, applied to the analysis of non-invasive MCA velocity measurements, for the prediction of changes to intracranial compliance, are considered to be original contributions to knowledge. In particular the proposed method of presenting the 'transit time' and the 'frequency centroid', simultaneously, on a two-dimensional map, is not only original, but also potentially an improvement to the data presentation methods for intracranial parameters that are currently in use in neurological units.
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Published date: 1999
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Local EPrints ID: 463917
URI: http://eprints.soton.ac.uk/id/eprint/463917
PURE UUID: f58c77da-0056-456b-8749-8dfa68642950
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Date deposited: 04 Jul 2022 20:58
Last modified: 04 Jul 2022 20:58
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Author:
Richard Peter Penson
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