Intrinsic, widefield optical imaging of hemodynamics in rodent models of Alzheimer’s disease and neurological injury

Abstract

. The complex cerebrovascular network is critical to controlling local cerebral blood flow (CBF) and maintaining brain homeostasis. Alzheimer’s disease (AD) and neurological injury can result in impaired CBF regulation, blood–brain barrier breakdown, neurovascular dysregulation, and ultimately impaired brain homeostasis. Measuring cortical hemodynamic changes in rodents can help elucidate the complex physiological dynamics that occur in AD and neurological injury. Widefield optical imaging approaches can measure hemodynamic information, such as CBF and oxygenation. These measurements can be performed over fields of view that range from millimeters to centimeters and probe up to the first few millimeters of rodent brain tissue. We discuss the principles and applications of three widefield optical imaging approaches that can measure cerebral hemodynamics: (1) optical intrinsic signal imaging, (2) laser speckle imaging, and (3) spatial frequency domain imaging. Future work in advancing widefield optical imaging approaches and employing multimodal instrumentation can enrich hemodynamic information content and help elucidate cerebrovascular mechanisms that lead to the development of therapeutic agents for AD and neurological injury.

Research on the classification of early‐stage brain edema by combining intrinsic optical signal imaging and laser speckle contrast imaging

“…Cerebral blood flow (CBF) and blood oxygen saturation, as significant indices of brain metabolism, have recently become a focus in brain edema research [ 9,10]. Positron emission tomography (PET) and magnetic resonance imaging (e.g., arterial-spin-labeled MRI) are the current clinical methods for directly monitoring CBF and oxygen saturation [11,12]. While these methods are capable of quantitatively measurement, their limited spatial resolution and extensive scanning time hinder the continuous monitoring of hemodynamic changes bedside.…”

Quantitative hemodynamic imaging: a method to correct the effects of optical properties on laser speckle imaging

“…In preclinical models, the change in cortical hemodynamics can be quantified using reflectance techniques, such as laser speckle imaging (LSI) and optical intrinsic signal imaging (OISI) 5 – 8 LSI measures cerebral blood flow (CBF), 9 while OISI measures hemoglobin concentrations and their derivative parameters, such as cerebral blood volume and tissue oxygen saturation (StO2) 5 , 10 – 12 With LSI, local speckle contrast values approximate the speckle decorrelation time, which is assumed to be inversely proportional to the speed of moving scatterers, such as red blood cells 9 .…”

A Brief Introduction to the Study of Cerebral Blood Flow Measurement in Traumatic Brain Injury Using Optical Imaging Approach

“…Since these change of light contrast fundamentals depending on specific wavelength, it is recommended to match the optimized light wavelength for the characteristics of the equipment. 3) Among these ways, optical imaging properties studied related to traumatic brain injury (TBI) are LSI and SFDI.…”

“…First of all, LSI is a wide-field imaging technique used in various fields of optic medicine to analyze specific tissues and cell perfusion related to blood flow using speckle interference patterns of light. 3) The main advantage of the LSI technology is the possibility of evaluating the characteristics of pulsations in addition to the average characteristics, which can help assess the rest or the functional state of blood flow. 5) LSI has been used to analysis the spatiotemporal CBF hemodynamic changes that occur in different models of TBI, such as modified cortical flow impact for more severe TBI and closed head injury for mild TBI.…”