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Glaucoma is one of the leading cause of blindness. The manual examination of optic cup and disc is a standard procedure used for detecting glaucoma. This paper presents a fully automatic regression based method which accurately segments optic cup and disc in retinal colour fundus image. First, we roughly segment optic disc using circular hough transform. The approximated optic disc is then used to...
Light-induced artifacts in metal-based microelectrodes significantly limit simultaneous use of electrophysiology with optogenetics or optical imaging. In this work, we systematically investigate light-induced artifacts in Au and transparent graphene electrodes fabricated in the same batch. We demonstrate that the Au electrodes show light artifacts resembling genuine local field potentials, while graphene...
Glaucoma is the second leading cause of blindness and it has been the topic of massive studies to explore the underlying mechanisms of the disease. Resting-state neuroimaging studies have been widely applied to investigate the functional damage of the brain, but little is known about the alterations of the interhemispheric resting-state functional connectivity (RSFC) in patients with primary open-angle...
The murine model is commonly utilized for studying developmental diseases. Different optical techniques have been developed to image mouse embryos, but each has its own set of limitations and restrictions. In this study, we compare the performance of the well-established technique of optical coherence tomography (OCT) to the relatively new methods of selective plane illumination microscopy (SPIM)...
Functional optical imaging (OI) of intrinsic signals (like blood oxygenation coupled reflection changes) and of extrinsic properties of voltage sensitive probes (like voltage-sensitive dyes (VSD)) forms a group of neuroimaging techniques that possess up to date highest temporal and spatial resolution on a meso-to macroscopic scale. An inherent problem of OI is a very low signal to noise ratio (SNR),...
Limited field of view (FOV) is a major problem for 3D real-time echocardiography (3DRTE), which results in an incomplete representation of cardiac anatomy. Various image registration techniques have been proposed to improve the field of view in 3DRTE by fusing multiple image volumes. However, these techniques require significant overlap between the individual volumes and rely on high image resolution...
In this paper, we propose a novel computer vision technique to measure respiration rate by counting the periodic thoracoabdominal motion in real-time using an inexpensive consumer grade camera. We compute the component of optical flow parallel to the image gradient at each pixel, which is a computationally inexpensive operation. Then, we find a principal flow field by gathering information over many...
Lung tumor segmentation is important for therapy in the radiation treatment of patients with thoracic malignancies. In this paper, we describe a 4D image segmentation method based on graph-cuts optimization, shape prior and optical flow. Due to small size, the location, and low contrast between the tumor and the surrounding tissue, tumor segmentation in 3D+t is challenging. We performed 4D lung tumor...
In this study we applied phase-space analysis on the hemodynamic signals recorded from the motor cortex of human subjects using functional near infrared spectroscopy (fNIRS) to decode the direction of intentional hand movements. Our goal is to develop a brain-computer-interface (BCI) based on optical imaging that can control a wheelchair. To establish the relationship between the hemodynamic response...
Neovascularization (NV) is a definitive indicator for the onset of Proliferative Diabetic Retinopathy (PDR). The new vessels are fragile and prone to bleed, leading to high risk of sudden vision loss. Automatic detection of NV is an important task in automatic Diabetic Retinopathy (DR) screening as a consequence of the unmet requirement between the growing number of DR patients and limited number...
Automated glaucoma detection is an important application of retinal image analysis. Compared with segmentation based approaches, image classification based approaches have a potential of better performance. However, it still remains a challenging problem for two reasons. Firstly, due to insufficient sample size, learning effective features is difficult. Secondly, the shape variations of optic disc...
This paper deals with the development of a fast and smart acquisition technique of Optical Coherence Tomography (OCT) data that has the capability to reconstruct missing data of OCT image. The main objective is to reduce the acquisition time (i.e., increase the frame rate) of an OCT-scan system by choosing a trajectory that covers entirely the image but that does not take all the measurements. The...
Functional Optical Imaging (OI) through the opened skull forms a group of Neuroimaging techniques characterized by a high temporal and spatial resolution on a meso-to macroscopic scale. State of the art OI experiments are generally difficult to execute, with a very timely surgical preparation preceding the experiment, that requires a skilled surgeon to mount a sealed imaging chamber onto the skull...
We present an inexpensive imaging system for measuring the diffuse surface radiance profile produced by a light source within a turbid medium. The diffusion model of light propagation in multiple scattering media is used to estimate the optical properties of a sample and subsequently approximate the depth of an optical source. The system is shown to accurately estimate the relative changes in source...
With the increased prevalence of retinal pathologies, automating the detection and progression measurement of these pathologies is becoming more and more relevant. Color fundus photography is the leading modality for assessing retinal pathologies. Because eye fundus cameras have a limited field of view, multiple photographs are taken from each retina during an eye fundus examination. However, operators...
Electrical stimulation of the retina is now firmly established as a means of restoration of rudimentary vision for blindness particularly that caused by retinitis pigmentosa. Of the various approaches, the novel positioning of an ultra-thin stimulating electrode array (SEA) posterior to the choroid has shown promising results. Following their implantation, reliable imaging methods are essential to...
It is estimated that approximately 30% of ischemic strokes are caused by rupture of plaque in the carotid artery. Development of techniques focusing on identifying plaques that are vulnerable to rupture is thus indispensable for stroke prevention. Recent studies have demonstrated that motion analysis of plaques from B-mode and RF ultrasound (US) image sequences can be used to estimate plaque strain...
For the real-time fusion of different modalities, a variety of tracking methods are available including the optical, electromagnetic (EM) and image-based tracking. But as a drawback optical tracking suffers from line of sight issues and EM tracking requires the manual referencing for the fusion procedure and is not usable in Magnetic Resonance Imaging (MRI) environment. To avoid these issues, we propose...
Assessment of arterio-venous fistula (AVF) blood flow (ABF) is vital in hemodialysis (HD) patients. Currently, no non-invasive and contact-free technique is available to accurately measure ABF in routine clinical practice. In this study, we developed a novel approach using video image processing (VIP) to measure the change in optic flow in the skin. We the tested the hypothesis that the change in...
CMOS-based opto-electronic neural interface devices are presented. The devices are designed with target application of in vitro and in vivo optogenetics. Two types of the opto-electronic neural interface devices are presented. One is single-chip type device for on-chip optogenetics, and the other is multi-chip type device with flexibility and wide-area coverage for in vivo optogenetics on brain. Design,...
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