Dissertation
Optical assessment of vascular disease progression and treatment
Doctor of Philosophy (Ph.D.), Drexel University
Apr 2014
DOI:
https://doi.org/10.17918/etd-4567
Abstract
Vascular disease manifests itself in many different forms, including chronic ulcers which do not heal, impaired blood flow to the limbs, or damage to the natural reperfusion process. The current forms of assessing vascular disease are often subjective and provide incomplete knowledge about the tissue of interest. This work focused on developing non-invasive techniques to quantitatively evaluate three specific elements of vascular disease: diabetic ulcers, venous ulcers, and peripheral arterial disease. Diffuse Near Infrared Spectroscopy (DNIRS) was used to predict healing (82% positive predictive value) in diabetic ulcers after 4 weeks of assessment (sensitivity of 0.9 and specificity of 0.86; p<0.002), proving to be an alternative and superior method to wound size reduction alone (the current gold standard). A novel therapeutic ultrasound treatment for venous ulcers, using a low-frequency (20kHz), low intensity (<100mW/cm2 ISPTP), fully-wearable applicator, was assessed using DNIRS and Diffuse Correlation Spectroscopy (DCS), wherein it was established that capillary flow changes over time in healing venous ulcers compared to wounds which do not heal (p<0.01). It was also determined that the ultrasound therapy was successful at improving wound outcomes, specifically the rate of wound closure per week (p<0.05 for wound size, p<0.01 for optical data). Finally, DNIRS and DCS were used in conjunction to assess the reactive hyperemic response in patients with suspected Peripheral Arterial Disease (PAD). It was found that the time between the release of cuff occlusion in the diseased limb and the first peak of reperfusion (flow mediated dilatation) correlated to PAD severity, with longer times (>30 seconds) belonging to patients with PAD (p<0.05). Additionally, it was discovered that the magnitude of the reperfusion did not relate to PAD, but rather to tobacco use. Patients who smoked had reduced hyperemic responses (p<0.02), whether or not they had PAD. Overall, this work represents an improvement over gold standard qualitative assessments of vascular health and the results obtained promise to develop new clinically relevant and quantitative techniques using non-invasive optical modalities.
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Details
- Title
- Optical assessment of vascular disease progression and treatment
- Creators
- Joshua A. Samuels - DU
- Contributors
- Peter Andreas Lewin (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems (1997-2026); Drexel University
- Other Identifier
- 4567; 991014632400604721