Abstract
Label-free multispectral optoacoustic tomography (MSOT) has recently shown superior performance in visualizing the morphology of human vasculature, especially of smaller vessels, compared to ultrasonography. Herein, we extend these observations towards MSOT interrogation of macrovascular endothelial function. We employed a real-time handheld MSOT scanner to assess flow-mediated dilatation (FMD), a technique used to characterize endothelial function. A data processing scheme was developed to quantify the dimensions and diameter changes of arteries in humans and determine wall distensibility parameters. By enabling high-resolution delineation of the blood-vessel wall in a cross-sectional fashion, the findings suggest MSOT as a capable alternative to ultrasonography for clinical FMD measurements.
Highlights
Optoacoustic contrast in the near-infrared region (650-850 nm) is attributed primarily to light absorption by oxygenated and deoxygenated hemoglobin
This study presents a proof of concept for the use of multispectral optoacoustic tomography (MSOT) for real-time flow-mediated dilatation (FMD) testing of macrovascular endothelial function in humans within the clinical setting
MSOT FMD tests relied on imaging the radial artery cross-section and quantitatively assessing its contour using a fitted ellipse
Summary
Optoacoustic contrast in the near-infrared region (650-850 nm) is attributed primarily to light absorption by oxygenated and deoxygenated hemoglobin. Since blood vessels concentrate high amounts of hemoglobin, they present excellent targets for optoacoustic imaging [1]. The capacity of optoacoustic tomography to visualize human vasculature was compared with ultrasound and Doppler ultrasound [2]. It was shown that the optoacoustic method outperforms ultrasonography, by providing a more accurate vessel representation, in particular regarding meso- and micro-vasculature. The multispectral optoacoustic tomography (MSOT) ability to resolve human vasculature has been demonstrated in several reports, using different scanner configurations [3,4]. Recent development of fast-tuning lasers offering >50 mJ energy per pulse has allowed the application of single-pulse-per-frame (SPPF) acquisition [6], which uses a single laser pulse to collect a cross-sectional image from tissue without averaging data from multiple pulses. The potential of SPPF for MSOT interrogation of physiological processes and vascular dynamics remains largely unexplored
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