Laser speckle contrast imaging for intraoperative monitoring of cerebral blood flow
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Ensuring adequate blood flow during surgical procedures is crucial, as prolonged ischemia can result in tissue death and lead to poor clinical outcomes. This is especially important during neurosurgery, since the brain relies on a constant supply of cerebral blood flow (CBF) to maintain normal function. Intraoperative blood flow monitoring tools are essential to detect ischemia in a timely manner, and allow surgical correction before the onset of irreversible brain injury. Laser speckle contrast imaging (LSCI) is an optical imaging method that provides blood flow maps with high spatiotemporal resolution, and overcomes many of the limitations of current intraoperative monitoring technologies. The objective of this dissertation is to demonstrate that LSCI is an effective tool for blood flow monitoring during neurosurgery, and to optimize and improve LSCI technology for clinical use. This research has two primary elements: assessing the LSCI instrumentation components in a controlled laboratory setting, and evaluating the clinical performance of LSCI during neurosurgery. The laboratory study aims to determine the optimal specifications for the clinical instrument design, using controlled static and microfluidic flow experiments. Two of the main components of the LSCI instrument are the camera used for recording, and the laser used for coherent illumination of the tissue. Thus, a broad camera and laser comparison was performed spanning a wide array of available hardware options to determine which specifications are the most important for reliable and highly sensitive flow measurements. The two-phase clinical study aims to demonstrate the performance and utility of LSCI in a neurosurgical setting as a potential tool for real-time, continuous, and noninvasive image guidance. These studies demonstrate that LSCI can produce blood flow maps consistent with expected physiological trends, and show the impact of instrument design and image acquisition techniques on image quality and quantitative flow assessment. The results from both the laboratory and clinical studies can be used to design a more sensitive and robust LSCI system, which increases its value as an intraoperative tool for monitoring blood flow. LSCI has the potential to be the next generation of neurosurgical image guidance for blood flow visualization, and the work presented in this dissertation can accelerate its clinical adoption.