Photoacoustic Microscopy Studies On Cat Primary Visual Cortex

Photoacoustic imaging is a hybrid non-invasive medical imaging modality in recent years,which is able to combine advantages of tissue imaging resolution in depth by acoustical methods and tissue structural information by optical methods,and it have been a research highlight in biomedical imaging field.Photoacoustic imaging can make up disadvantages of traditional imaging modalities to achieve high-resolution and multi-parameter imaging of cerebral vascular network.At present,applications of photoacoustic imaging on cortex are mainly restricted to small-animal model.Feline is classic animal model in the field of visual neuroscience.Based on high-resolution structural and functional imaging on cat visual cortex vascular network by photoacoustic microscopy,we can provide a new technique for visual science research on large-animal model such as feline,which has an important practical meaning.This research applies optical resolution photoacoustic microscopy system on large-animal model to image unlabeled microvascular structure and oxyhemoglobin saturation on primary visual cortex of cat,and monitor change of oxygen saturation of arteries in cardiac cycle,which provides theoretical basis and experimental data for prospective high-resolution structural and functional imaging on cat visual cortex and related applications.Firstly,we designed flow of animal experiment and image the whole area of cat visual cortex after craniotomy based on performance of photoacoustic microscopy system.Then we combined results of ultrasonic imaging to acquire information of cortex surface.The quality of 3Dstructural imaging is guaranteed on level of capillary.Then,based on physical mechanism of photoacoustic signal generation and measurement process of oxygen saturation,we designed numerical simulation on effect of multiple factors on amplitude of photoacoustic signals and oxygen saturation to verify reliability of signals on functional imaging.And we process compensation on photoacoustic signals of visual cortex vessels based on results of simulation to improve smoothness and accuracy of oxygen saturation measurement.Finally,we imaged oxygen saturation on area of interest of cortex based on improved structural imaging.Phantom tests is applied to verify reliability of signal quantification.Then we chose area of interest to image distribution of oxygen saturation,in which oxygen saturation of arteries and veins are distinguished.In addition,we also process measurement on blood oxygenation of pulsatile arteries to watch changes of oxygen saturation in a whole cardiac cycle.