Investigating changes in regional brain temperature in patients suffering ischaemic stroke

Abstract

Stroke is a leading cause of death and disability around the world. Current acute treatments are potentially dangerous and must typically be delivered within a very limited time window to be effective. Current research into ischaemic stroke includes the search for novel therapeutic agents, as well as for techniques that may help identify patients likely to benefit from potentially dangerous therapies such as thrombolysis, or extend the time window within which these therapies are likely to be effective. Brain temperature is potentially significant in all three of these avenues of investigation. Hypothermia may be neuroprotective in its own right and may extend the time window for effective treatment with existing medications. Conversely, elevated temperature may exacerbate ischaemic injury and thus worsen a patient’s prognosis. However, measuring localised brain temperature, as opposed to body temperature, is extremely difficult. In this thesis two tools are developed with which to investigate regional brain temperature in patients suffering ischaemic stroke. A method of Magnetic Resonance Thermography (MRT), which provides a method for measuring regional brain temperature non-invasively, is developed using readily available medical imaging technology and allows estimation of temperature in healthy volunteers with an accuracy of ±1.3°C. This tool is not yet sensitive enough for routine clinical use but has the potential to be developed further. A Finite Element Model (FEM) is developed to simulate heat exchange in the stroke-affected brain. This model is validated against experimental data from the literature and is found to be valid for normal tissue, but underestimate temperature changes in ischaemic tissue. The potential implications of this finding are discussed; in particular, it appears that the changes to the process of heat exchange in ischaemic brain tissue are more complex than previously thought. Show more