We propose a new alignment method for three-dimensional optical coherence tomography (OCT) images. Recently, OCT devices have been developed that can capture three-dimensional tomographic images of retina non-contactly and non-invasively. However, eye movement artifacts in scanning make 3D reconstruction and 3D image processing difficult. In this paper, we propose a method to search the best position automatically by using normalized correlation in two directions (vertical and horizontal directions). This paper applied the proposed method to 7 OCT image sets (4 sets of normal retinal images and 3 sets of abnormal retinal images). The generated images by the proposed method are ...

Current methods to build dynamic optical coherence tomography (OCT) volumes of the beating embryonic heart involve synchronization of 2D+time slice-sequences acquired over separate heartbeats. Temporal registration of these sequences is performed either through gating or post-processing. While synchronization algorithms that exclusively rely on image-intrinsic signals allow forgoing external gating hardware, they are prone to error accumulation, require operator-supervised correction, or lead to non-isotropic resolution. Here, we propose an imagebased, retrospective reconstruction technique that uses two sets of parallel 2D+T slice-sequences, acquired perpendicularly to each other, to yield accurate and automatic reconstructions with isotropic resolution. The method utilizes the ...

Optical Coherence Tomography is a well established image modality in ophthalmology and used daily in the clinic. Automatic evaluation of such datasets requires an accurate segmentation of the retinal cell layers. However, due to the naturally low signal to noise ratio and the resulting bad image quality, this task remains challenging. We propose an automatic graphbased multi-surface segmentation algorithm that internally uses soft constraints to add prior information from a learned model. This improves the accuracy of the segmentation and increase the robustness to noise. Furthermore, we show that the graph size can be greatly reduced by applying a smart ...

We have been investigating ultrahigh resolution optical coherence tomography using supercontinuum. Low noise, Gaussian like supercontinua were generated at five wavelength regions. Ultrahigh resolution cross-sectional and three dimensional imaging were demonstrated for biomedical tissues and materials.

Blood Flow plays an important role during the early stage development of embryogenesis. Spectral domain optical coherence tomography (SDOCT), with high resolution and high acquisition speed, has been widely used in biological tissue imaging in recent years. By evaluation of phase difference between consecutive A-scan lines, SDOCT provides the ability for flow velocity measurement. In order to find the optimize SDOCT system for early stage chicken embryo heart outflow tract (OFT) flow measurement, two spectral domain optical coherence tomography setups were built in our lab with different central wavelength, i.e. 845nm and 1321nm. The performances of the two systems ...

The feasibility of characterization of human blood fibrinogen levels using optical coherence tomography (OCT) was investigated. Three groups of blood samples were reconstituted of red blood cells and, I. phosphate buffered saline, II. plasma with its intrinsic fibrinogen removed and commercial fibrinogen added, III. native plasma with various fibrinogen levels (0-12 g/L). OCT signal slope (OCTSS) of blood was extracted from OCT depth-reflectivity profiles. Effects of hematocrit (HCT) and blood flow on OCTSS of the blood under various fibrinogen concentrations were also studied. The results of blood flowing at 5 mm/sec showed that OCTSS of all the three ...

Segmenting retinal vessels in optic nerve head (ONH) centered spectral-domain optical coherence tomography (SD-OCT) volumes is particularly challenging due to the projected neural canal opening (NCO) and relatively low visibility in the ONH center. Color fundus photographs provide a relatively high vessel contrast in the region inside the NCO, but have not been previously used to aid the SD-OCT vessel segmentation process. Thus, in this paper, we present two approaches for the segmentation of retinal vessels in SD-OCT volumes that each take advantage of complimentary information from fundus photographs. In the first approach (referred to as the registeredfundus vessel segmentation ...

This work investigates the autocorrelation bandwidths of dual window (DW) optical coherence tomography (OCT) k-space scattering profile of different-sized microspheres and their correlation to scatterer size. A dual bandwidth (DB) spectroscopic metric defined as the ratio of the 10% to 90% autocorrelation bandwidths is found to change monotonically with microsphere size and gives the best contrast enhancement for scatterer size differentiation in the resulting spectroscopic image. A simulation model supports the experimental results and revealed a trade-off between the smallest detectable scatterer size and the maximum scatterer size in the linear range of the DWDB metric, which depends on the ...

Optical Coherence Tomography (OCT) is an imaging mod-ality that has several advantages (e.g. high resolution and three dimensional imaging) in comparison with other oph-thalmic imaging methods. Retinal structures, such as the optic nerve head (ONH), can be examined in detail. The geometry of the ONH can offer valuable information for the detection of glaucoma, because it is affected by this disease. However, manual examinations are highly subjective. In this study we present an approach using morphological operators for the completely automated segmentation of the ONH region, which is crucial for the further examination of the geometrical parameters that indicate ...

Recently, compressive sampling has received significant attention as an emerging technique for rapid volumetric imaging. We have previously investigated volumetric Optical Coherence Tomography (OCT) image acquisition using compressive sampling techniques and showed that it was possible to recover image volumes from a subset of sampled images. Our previous findings used the multi-dimensional wavelet transform as the domain of sparsification for recovering OCT image volumes. In this report, we analyzed and compared the potential and efficiency of three other image transforms to reconstruct the same volumetric OCT image. Two quantitative measures, the Mean Square Error (MSE) and the Structural SIMilarity index ...

A novel prototype of electrothermal chevron-beam actuator based microelectromechanical systems (MEMS) platform has been successfully developed for circumferential scan. Microassembly technology is utilized to construct this platform, which consists of a MEMS chevron-beam type microactuator and a micro pyramidal polygon reflector. The proposed electrothermal microactuators with a two-stage electrothermal cascaded chevron-beam driving mechanism provide displacement amplification, and thus driving a highly reflective micro-pyramidal polygon reflector to rotate a large angle for light beam scan. This MEMS platform is ultra-compact, supports circumferential imaging capability, and is suitable for endoscopic optical coherence tomography (EOCT) application, for example intravascular cancer detection.

We report on real-time control of balloon inflation inside porcine arteries. In a first step, experiments were done in a coronary artery of an excised heart. In a second step, experiments were done in a beating heart setup providing conditions very close to in vivo conditions without the complications. A programmable syringe pump was used to inflate a compliant balloon in arteries, while intravascular optical coherence tomography (IVOCT) monitoring was performed. In a feedback loop, IVOCT images were processed to provide the balloon diameter values in real-time to control the pump action in order to achieve a target diameter. In ...

In this paper, we introduce a 2-D microelectromechanical systems scanner for 3.2-mm-diameter dual-axis confocal microendoscopes, fabricated exclusively by front-side processing. Compared to conventional bulk micromachining that incorporates back-side etching, the front-side process is simple and thus enables high device yield. By eliminating the back-side etch window, the process yields compact and robust structures that facilitate handling and packaging. An important component of our front-side fabrication is a low-power deep reactive ion etching (DRIE) process that avoids the heating problems associated with standard DRIE. Reducing the RF etch coil power from 2400 to 1500 W leads to elimination of the ...

We discuss BioThreads, a novel, configurable, extensible system-on-chip multiprocessor and its use in accelerating biomedical signal processing applications such as imaging photoplethysmography (IPPG). BioThreads is derived from the LE1 open-source VLIW chip multiprocessor and efficiently handles instruction, data and thread-level parallelism. In addition, it supports a novel mechanism for the dynamic creation, and allocation of software threads to uncommitted processor cores by implementing key POSIX Threads primitives directly in hardware, as custom instructions. In this study, the BioThreads core is used to accelerate the calculation of the oxygen saturation map of living tissue in an experimental setup consisting of a ...

A method is proposed to achieve computerized control of angioplasty balloon inflation, based on feedback from intravascular optical coherence tomography (IVOCT). Controlled balloon inflation could benefit clinical applications, cardiovascular research, and medical device industry. The proposed method was experimentally tested for balloon inflation within an artery phantom. During balloon inflation, luminal contour of the phantom was extracted from IVOCT images in real-time. Luminal diameter was estimated from the obtained contour and was used in a feedback loop. Based on the estimated actual diameter and a target diameter, a computer controlled a programmable syringe pump to deliver or withdraw liquid in ...

Optical coherence tomography (OCT) is a high-resolution imaging modality with the potential to provide in situ assessment to distinguish normal from cancerous tissue. However, limited image penetration depth has restricted its utility. This paper demonstrates the feasibility of an OCT needle probe to perform interstitial imaging deep below the tissue surface. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fiber encased within either a 22- or 23-gauge needle. 3D-OCT volumetric data sets were acquired by rotating and retracting the probe during imaging. We present the first published image of a human breast cancer tumor margin ...