We report on a new articular cartilage imaging technique with potential for clinical arthroscopic use, by supplementing the variable-incidence-angle polarization-sensitive optical coherence tomography method (VIA-PS-OCT) previously developed by us with a conical beam scan protocol. In the protocol, the beam is scanned such that the k-vector sweeps out a conical surface whose apex is chosen, for convenience, to lie at the tissue surface. In the implementation reported here we achieve this by mounting the sample on a motorized rotation stage with the sample surface roughly parallel to the stage rotating plane (i.e. normal to the stage rotation axis). The ...
A 71-year-old man underwent endovascular therapy (EVT) with a paclitaxel-eluting stent in superficial femoral artery (SFA). Optical coherence tomography (OCT) of SFA at 2 months after EVT revealed that several struts were not covered with neointima. Moreover, some mural thrombi were detected within the stent. Although OCT revealed that the frequency of stent strut coverage was improved at the 4-month follow-up, uncovered stent strut still remained and some mural thrombi were observed within the stent even at 4 months after EVT. This is the first report to demonstrate the vascular response after paclitaxel-eluting stent placement for the lesion using serial ...
Optical coherence tomography has been proven in the last two decades its clinical value by providing 3D non-invasive in vivo biopsy of the biological samples. In addition to structural information given by the backscattered intensity, the optical absorption will also provide another powerful contrast. Optical absorbers in biological tissues exhibits important role such as hemoglobin and melanin. However, current methods of absorption contrast take long time and not suitable for in vivo imaging. Toward in vivo absorption contrast imaging, we developed photothermal OCT system by combining swept-source OCT system and excitation laser. A swept-source OCT system is used with a ...
There are several applications of quantitative micro-displacement measurement of a biological specimen, including characterization of mechanical property and monitoring a laser-induced photothermal expansion. In this study, we proposed a quantitative micro-displacement measurement method using optical coherence tomography (OCT). Specifically, the axial displacement is measured by Doppler OCT and magnitude of displacement is measured by correlation coefficient. By using this method, we measured the local and microdisplacement of the chicken muscles during laser irradiation. The proposed method successfully visualizes thermal changes of chicken muscle due to the laser irradiation. The measured displacement and deformation are useful information for the further understanding ...
Pixel clustering algorithm tailored to multi-contrast Jones matrix based optical coherence tomography (MC-JMT) is demonstrated. This algorithm clusters multiple pixels of MC-JMT in a five-dimensional (5-D) feature space which comprises dimensions of lateral space, axial space, logarithmic scattering OCT intensity, squared power of Doppler shift and degree of polarization uniformity. This 5-D clustering provides clusters of pixels, so called as superpixels. The superpixels are utilized as local regions for pixels averaging. The averaging decreases the noise in the measurement as preserving structural details of the sample. A simple decision-tree algorithm is applied to classified superpixels into some tissue types. This ...
An advanced version of Jones matrix optical coherence tomography (JMT) is demonstrated for Doppler and polarization sensitive imaging of the posterior eye. JMT is capable of providing localized flow tomography by Doppler detection and investigating the birefringence property of tissue through a three-dimensional (3-D) Jones matrix measurement. Owing to an incident polarization multiplexing scheme based on passive optical components, this system is stable, safe in a clinical environment, and cost effective. Since the properties of this version of JMT provide intrinsic compensation for system imperfection, the system is easy to calibrate. Compared with the previous version of JMT, this advanced ...
We have grown monolithic multi-color InAs quantum dots (QDs) for use as a near-infrared (NIR) broadband light source. Our previously developed rotational metal mask enables selective-area growth of QD ensembles with emission peak wavelengths controlled by strain-reducing layers thicknesses, varying the emission approximately 1.2–1.3 μ m. The peak shift value was up to 120 nm, and a combined 160-nm-bandwidth emission spectrum was achieved. Further, the emission spectra shapes were controlled using specific optical excitation powers for each QD ensemble. These results demonstrate the effectiveness of multi-color QDs as a spectrum-shape-controllable NIR broadband light source, particularly suited for optical ...
University of Tsukuba is located in the city of Tsukuba. The university is ranked one of the top Asian universities in the "Academic Ranking of World Universities" and is ranked 102-150 in the world. The University of Tsukuba has had several Nobel Prize winners so far, namely Leo Esaki, Hideki Shirakawa and Sin-Itiro Tomonaga, which is extremely rare among universities in Asia, where there have been fewer Nobel laureates than in European and American universities.