Minicourse-08

Synopsis: The ability to monitor CBF is essential in gaining a deeper understanding of neuro-vascular coupling, especially in the presence of pathological changes. At the same time, CBF is a fundamental biomarker of brain health and can be of clinical value for the management of patients with potentially impaired cerebral perfusion, such as patients under anesthesia, or those who have suffered traumatic brain injuries or stroke. Diffuse Correlation Spectroscopy offers a method to directly monitor tissue perfusion non-invasively by quantifying the intensity fluctuations of light diffusely reflected from tissue, fluctuations predominantly driven by light scattering from moving red blood cells. We will present the theoretical basis of DCS based on dynamic light scattering and the correlation diffusion equation, and describe practical DCS system design and operation, using the DCS instruments designed in house at MGH as a basis for discussion.

Course description and structure: We will conduct a hands-on demonstration in which data will be acquired on a volunteer’s forearm during a blood-pressure cuff occlusion maneuver and also on a volunteer’s forehead during a probe pressure modulation maneuver. We will demonstrate data analysis based on both analytical and Monte-Carlo models, using tools developed by the MGH team and conduct an interactive discussion with participants. We will give an outlook on future developments of DCS technology including alternative experimental approaches (time-resolved, ultrasound tagging, low-cost systems).

Learning objectives: At the completion of this course participants will be able to:

• Describe the fundamental principles behind blood flow measurement using diffuse correlation spectroscopy
• Describe the key components of a DCS system including light sources, detectors, probes and electronics
• Perform basic DCS in-vivo measurements and analyze DCS data to extract perfusion time-courses
• Describe approaches for multi-layer light transport modeling and their application to CBF quantification in adults
• Understand limitations of current systems and future area of technology development