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Spinal cord injury (SCI) affects approximately 2.5 million people worldwide. The primary phase of SCI is initiated by mechanical trauma to the spinal cord, while the secondary phase involves the ensuing tissue swelling and ischemia that worsen tissue damage and functional outcome. Optimizing blood flow to the spinal cord after SCI can mitigate injury progression and improve outcome. Accurate, sensitive, real-time monitoring is critical to assessing the spinal cord perfusion status and optimizing management, particularly in those with injuries severe enough to require surgery. However, the complex anatomy of the spinal cord vasculature and surrounding structures present significant challenges to such a monitoring strategy. In this study, Doppler ultrasound was hypothesized to be a potential solution to detect and monitor spinal cord tissue perfusion in SCI patients who required spinal decompression and/or stabilization surgeries. This approach could provide real-time visual blood flow information and pulsatility of the spinal cord as biomarkers of tissue perfusion. Importantly, Doppler ultrasound could be readily integrated into the surgical workflow, because the spinal cord was exposed during surgery, thereby allowing easy access for Doppler deployment, while keeping the dura intact. Doppler ultrasound successfully measured blood flow in single and bifurcated microfluidic channels at physiologically relevant flow rates and dimensions in both in-vitro and in-vivo porcine SCI models. Furthermore, perfusion was quantified from the obtained images. Our results provide a promising and viable solution to intraoperatively assess and monitor blood flow at the SCI site to optimize tissue perfusion and improve functional recovery in SCI patients.

This paper describes a combined ultrasonic and spectroscopic system for imaging both the structure and chemical composition of atherosclerotic plaque. Using this system, ultrasound pulse echo distance estimations can be used to accurately compensate detected tissue fluorescence intensities for a wide range of tissue-detector separations, D. Compensation is achieved using an empirical model, wherein fluorescence intensity decreases as 1/Dn with n equals 1.1 for tissue detector separations from 2.5 to 5 mm and 1.4 for separations of 5 to 15 mm. This behavior indicates that fluorescence exiting the tissue surface is not isotropic.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.