Quantitative Assessment and Characterization of Microvascular Function Using Diffuse Optical Tomography Version

Detailed Summary

Atherosclerosis is accompanied by microvascular dysfunction (an impairment of blood vessels to dilate or constrict in response to demand). The ability to reliably measure microvascular dysfunction would help identify patients at risk of myocardial infarction and test new treatments. All existing measures of microvascular dysfunction suffer significant limitations. Near Infrared Spectroscopy (NIRS) is an imaging method that uses an infrared light-source and detector (called optodes) to painlessly shines light into tissue and collect reflected light at different wavelengths. This data allows quantification of the amount of haemoglobin (blood) in the tissue and whether it is oxygenated or de-oxygenated. Diffuse optical tomography (DOT) is a powerful analysis technique for data collected from multiple NIRH optodes. Unlike most NIRS studies that use a single pair of optodes and collects a single datapoint for each wavelength over time, DOT allows three-dimensional spatial reconstruction of haemodynamic and anatomic changes in a large region of tissue over time. In preliminary work DOT had the potential to measure forearm reactive hyperaemia, a key indicator of microvascular function. Team will test whether DOT can detect differences between patients and healthy volunteers. In this work, 30 patients will be recruited with type 2 diabetes, 30 patients who have had a previous myocardial infarction and 30 healthy volunteers. The Investigator will also recruit 50 patients who are on waiting lists for coronary angiography. The DOT will be used to measure participants' microvascular function after brachial artery occlusion by a blood pressure cuff. The Investigator will then examine whether DOT can detect differences between healthy volunteers, diabetics, and patients with a previous heart attack, and whether DOT is able to predict existence of coronary artery disease on angiography. If successful, DOT can be developed for assessment of microvascular function to the point where it could be applied to clinical studies.

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