Multispectral optoacoustic tomography (MSOT) for clinical diagnosis and therapeutic monitoring of peripheral vascular disease (PVD)

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Peripheral vascular disease (PVD) is associated with significant morbidity caused by insufficient blood supply to the periphery (usually lower legs and feet), including ultimate amputation of limbs. Diagnosis of PVD is complicated by asymptomatic cases and a wide range of underlying diseases, including atherosclerosis-related occlusion of large arteries, microvascular disease linked to diabetes, hypertension, et cetera. Current diagnostic tools, including ankle-brachial index and duplex sonography, provide information on large vessel morphology and hemodynamics. However, the real problem caused by PVD, insufficient delivery of oxygen to the periphery, is not directly assessed. We propose to diagnose PVD patients with multispectral optoacoustic tomography (MSOT), which can provide functional images of the vasculature. Optoacoustic imaging has emerged as a highly promising modality for in vivo biomedical diagnostics. Energy deposited in the tissue by pulses of light causes absorbers to expand, giving rise to ultrasound waves that propagate outwards and can be detected noninvasively. This allows optical imaging at the high resolution of ultrasound up to depths of centimeters under the skin. Hemoglobin is a primary absorber of light in tissue, thus optoacoustic imaging resolves blood and vasculature. Multispectral Optoacoustic Tomography (MSOT) uses multiple excitation wavelengths to quantify specific absorbers, such as the different oxygenation states of hemoglobin, according to their spectra. We plan to apply MSOT to dynamically image the vasculature in the lower legs and feet of patients with suspected PVD, including large artery occlusion and microvascular disease, providing measures of oxygen delivery such as hemoglobin concentration and oxygenation. Additionally, we will investigate treatment monitoring, both by performing longitudinal measurements, and by applying MSOT during angioplasty procedures to provide real-time feedback.