3D Optical Imaging Of Microvascular Net-Works And Its Application On Cerebral Science

As an emerging three-dimensional optical imaging modality,optical coherence tomography(OCT)plays a vital role in a variety of fields such as biomedicine,with its favorable advantages of non-invasion,non-contact,high resolution and high sensitivity.With combination of traditional OCT that enables three-dimensional spatial resolution and dynamic light scattering that enables motion recognition,OCT angiography(OCTA)has been developed.OCTA employs the relative movement of the red blood cells with respect to the surrounding tissue as a label,which can substitute endogenous blood flow for the conventional exogenous fluorescent markers,and is capable of motion-contrast,label-free and three-dimensional blood perfusion imaging in vivo within the tissue bed down to the capillary level.This technology holds good prospects for its application in cerebral scientific and ophthalmologic research and clinic.This dissertation primarily involves some research effort in terms of label-free motion-contrast optical coherence tomography angiography and its applications on cerebral science on the basis of the OCT technology,especially the spectral domain OCT,comprising:A deep understanding of the spectral domain OCT(SD-OCT)imaging mechanism was made and several key SD-OCT performance parameters including resolution,signal-to-noise ratio,imaging range and sensitivity were analyzed.In order to interpret the mechanism of blood flow contrast in OCTA and to demonstrate that OCT is capable of detecting dynamic microscopic scatterers,the self-designed SD-OCT configuration was applied to the detection of microscopic particle dynamics,successfully achieving the ultrafast characterization of particle dynamics through parallel acquisition of mass samples.The blood flow motion-contrast mechanism in label-free OCTA was further elaborated on.To enhance the motion contrast in OCTA for a better interpretation of the angiograms,an angular diversity based collection of independent scattering samples through full-channel lateral modulation spectrum segmentation was proposed for generating angular resolved independent OCTA angiograms,which were further compounded and averaged.Furthermore,this collection was extended to the temporal,spatial and even spectral diversities and an effective hybrid mass-sample collection in parallel was achieved.The presented mass-sample OCTA offers a cost apportionment among imaging time,spatial,axial and lateral resolution with these four diversities combined and achieves an optimized flow contrast.Finally,a label-free,all-optical method of simultaneous neuronal manipulation and functional optical imaging using infrared neural stimulation(INS)and OCT,respectively,was proposed for cerebral scientific research.It was demonstrated that OCT can detect the spatio-temporal resolved functional activation changes evoked by INS stimulation on rat somatosensory cortex.The functional OCT response was highly synchronized to INS.In addition,differing from the depth-integrated functional OISI,the functional OCT revealed the depth-resolved activated responses.This research plays a vital role in the study on functional neuronal activities in cerebral science.