Jaeyul Lee

Imaging depth-resolved birefringence and optic axis orientation with polarization sensitive optical coherence tomography (PS-OCT) unveils details of tissue structure and organization that can be of high pathophysiologic, mechanistic, and diagnostic value. For catheter-based PS-OCT, the dynamic rotation of the fiber optic probe, in addition to the polarization effects of the system components, complicates the reliable and robust reconstruction of the sample’s optic axis orientation. Addressing this issue, we present a new method for the reconstruction of absolute depth-resolved optic axis orientation in catheter-based PS-OCT by using the intrinsic retardance of the protecting catheter sheath as a stable guide star signal. Throughout the paper, we rigorously inspect the retardance and optic axis orientation of the sheath and validate our method by imaging a birefringent phantom with known optic axis orientation. Reconstructing the optic axis orientation of the phantom, placed at different locations around the catheter, we measured an average absolute deviation (AAD) for the mean optic axis orientation over cross-sectional images of 3.28°, even with significant bending stress on the catheter. This corresponds to an almost three-fold improvement compared to our earlier method (optic axis AAD of 9.41°). We finally highlight the capability of our reconstruction with stereotactic catheter-based PS-OCT of a fresh sheep brain.

Rationale: Idiopathic pulmonary fibrosis (IPF) affects the subpleural lung but is considered to spare small airways. Micro–computed tomography (micro-CT) studies demonstrated small airway reduction in end-stage IPF explanted lungs, raising questions about small airway involvement in early-stage disease. Endobronchial optical coherence tomography (EB-OCT) is a volumetric imaging modality that detects microscopic features from subpleural to proximal airways. Objectives: In this study, EB-OCT was used to evaluate small airways in early IPF and control subjects in vivo. Methods: EB-OCT was performed in 12 subjects with IPF and 5 control subjects (matched by age, sex, smoking history, height, and body mass index). Subjects with IPF had early disease with mild restriction (FVC: 83.5% predicted), which was diagnosed per current guidelines and confirmed by surgical biopsy. EB-OCT volumetric imaging was acquired bronchoscopically in multiple, distinct, bilateral lung locations (total: 97 sites). IPF imaging sites were classified by severity into affected (all criteria for usual interstitial pneumonia present) and less affected (some but not all criteria for usual interstitial pneumonia present). Bronchiole count and small airway stereology metrics were measured for each EB-OCT imaging site. Measurements and Main Results: Compared with the number of bronchioles in control subjects (mean = 11.2/cm3; SD = 6.2), there was significant bronchiole reduction in subjects with IPF (42% loss; mean = 6.5/cm3; SD = 3.4; P = 0.0039), including in IPF affected (48% loss; mean: 5.8/cm3; SD: 2.8; P < 0.00001) and IPF less affected (33% loss; mean: 7.5/cm3; SD: 4.1; P = 0.024) sites. Stereology metrics showed that IPF-affected small airways were significantly larger, more distorted, and more irregular than in IPF-less affected sites and control subjects. IPF less affected and control airways were statistically indistinguishable for all stereology parameters (P = 0.36–1.0). Conclusions: EB-OCT demonstrated marked bronchiolar loss in early IPF (between 30% and 50%), even in areas minimally affected by disease, compared with matched control subjects. These findings support small airway disease as a feature of early IPF, providing novel insight into pathogenesis and potential therapeutic targets.

To identify the vascular alteration by photodynamic therapy (PDT), the utilization of high-resolution, high-speed, and wide-field photoacoustic microscopy (PAM) has gained enormous interest. The rapid changes in vasculature during PDT treatment and monitoring of tumor tissue activation in the orthotopic pancreatic cancer model have received limited attention in previous studies. Here, a fully two-axes waterproof galvanometer scanner-based photoacoustic microscopy (WGS-PAM) system was developed for in vivo monitoring of dynamic variations in micro blood vessels due to PDT in an orthotopic pancreatic cancer mouse model. The photosensitizer (PS), Chlorin e6 (Ce6), was utilized to activate antitumor reactions in response to the irradiation of a 660 nm light source. Microvasculatures of angiogenesis tissue were visualized on a 40 mm² area using the WGS-PAM system at 30 min intervals for 3 h after the PDT treatment. The decline in vascular intensity was observed at 24.5% along with a 32.4% reduction of the vascular density at 3 h post-PDT by the analysis of PAM images. The anti-vascularization effect was also identified with fluorescent imaging. Moreover, Ce6-PDT increased apoptotic and necrotic markers while decreasing vascular endothelial growth factor (VEGF) expression in MIA PaCa-2 and BxPC-3 pancreatic cancer cell lines. The approach of the WGS-PAM system shows the potential to investigate PDT effects on the mechanism of angiographic dynamics with high-resolution wide-field imaging modalities.

The research results are as follows. Mental management of self-management behaviors meaningful in all of the general characteristics such as gender, affiliation, and training period was found to have an effect on both cognitive and behavioral immersion, and interpersonal management, training management, and physical management were Accordingly, it was found that exercise immersion partially affected cognitive immersion and behavioral immersion. These results show that the foundation of Taekwondo is that it is easy to access home due to the nature of the Taekwondo dojo, so there are many cases where people come into contact with Taekwondo training from a young age. is presumed to be In addition, based on this, it is considered that the transition from Taekwondo training to student athletes or continuing training as a means for health and self-defense is considered to coincide with the period of preparation for higher education through career selection.

The aim of this study was to quantitatively assess the residual adhesive on orthodontic ceramic bracket-removed dental surface. In orthodontic process, ceramic bracket was repeated debonding physically, then the adhesive remained on the dental surface. The residual adhesive caused a lack of adhesive strength between dental and ceramic bracket. Since commonly used adhesive in orthodontics is translucent, residual adhesive is hard to be detected with conventional microscopes. Therefore, 1310 nm center wavelength swept-source OCT system based on laboratory customized image processing algorithm was used for the precise detection of residual adhesive on tooth surface. The algorithm separates residual adhesive from dental surface by comparing the height of adjacent B-scan images, while providing color-scaled images emphasizing the thickness information of residual adhesive. Finally, the acquired results were compared with microscopic and adhesive remnant index scoring gold standards, while the comparison confirmed the potential merits and the improvements of the proposed method over gold standards.

The successful surgery of chronic otitis media (COM) is challenging; this depends on the surgeon's knowledge of the optical visibility of surgical microscopes. Herein, we reported the utilization of intra-surgical optical coherence tomography (OCT) system to effectively guide the surgery of COM based on augmented reality with cross-sectional images. The intra-surgical spectral-domain OCT system with a center wavelength of 846 nm was capable of obtaining non-invasive, high-resolution, and high-speed visualizations with an axial resolution of 8 μm, lateral resolution of 30 μm, and an extended working distance of 280 mm. Three patients with COM were involved in this research. The lesion conditions of the temporal bone were observed with computed tomography pre-operatively. Furthermore, pure-tone audiogram examinations were performed to evaluate pre and post-surgical conditions. The results revealed that the averaged air-bone gap of 500 Hz, 1 kHz, 2 kHz, and 4 kHz in all cases improved to 61%. Thus, the research proves that the experimental procedure can be beneficial and clinically applicable with the developed intra-surgical OCT system for future otolaryngological assessments.

Digital impressions have been studied for better gingival retraction in including the under subgingival finish line condition. Here, we employed swept-source optical coherence tomography (SS-OCT) of 1310 nm wavelength, which is capable of noninvasive, high-resolution, and high-speed, to discern the utilization-possibility for supporting the fabrication of the dental crown. A three-dimensional (3D) abutment was used at the 0.5 mm of the subgingival finish line below the level of the gingiva. The SS-OCT system scanned a field of view of 10 mm × 10 mm using the 3D working model by the depth-directional three focal points. The obtained 1500 images of OCT cross-sections, which are 1221 × 1220 pixels, were rendered to the 3D model for the effective design of a virtual crown. Then, the ceramic crown was fabricated through a milling machine with a computer-aided design and computer-aided manufacturing (CAD/CAM) software. The marginal fit of the crown was evaluated 219.1 ± 48.9 μm by a silicone replica technique. Although the marginal fit is not sufficient for the clinical allowable gap at one resin typodont, this study can be anticipated to encourage further researches for the enhanced fabrication of dental crown under subgingival finish line conditions.

The accurate screening of otitis media (OM) lies in clarifying the numerous confounding and quantitative factors that are discovered during primary inspections. Increased awareness about bacterial biofilms and inflammation has allowed researchers to develop a better understanding of the bacterial infections that occur in the middle ear. In this study, four live guinea pigs were inoculated with Streptococcus pneumonia to induce OM-related inflammatory changes. Since optical techniques have been effectively used for diagnosis in medicine, low-coherence interferometry-based optical coherence tomography (OCT) was employed for depth-resolved high-resolution data screening. Multiple locations of the tympanic membrane (TM), mastoid mucosa, and round window membrane were examined to assess inflammatory changes. We performed qualitative assessments and thickness quantifications and investigated the variations due to adverse inflammatory affects. The findings of the present study provide a better understanding of S. pneumonia bacteria caused inflammatory changes in middle ear and it further provides a fundamental platform for future clinical utility.

Dental crowns are used to restore decayed or chipped teeth, where their surfaces play a key role in this restoration process, as they affect the fitting and stable bonding of the prostheses. The surface texture of crowns can interfere with this restoration process, therefore the measurement of their inner surface roughness is very important but difficult to achieve using conventional imaging methods. In this study, the inner surfaces of dental crowns were three-dimensionally (3D) visualized using swept-source optical coherence tomography (SS-OCT) system. Nine crowns were fabricated with a commercial 3D printer using three different hatching methods (one-way, cross, and 30° angle counter-clockwise) and three different build direction angles (0°, 45°, and 90°). In addition, an image processing algorithm was developed, which uses morphological filtering, boundary detection, and a high-pass frequency filtering technique, to quantitatively evaluate the inner surface roughness of the dental crowns cross-sections with the depth-of-focus set to match two different regions. The averaged smoothness of fabricated crown was effectively produced using the cross-hatching and the build direction angle of 90° by the respective process. Thus, the results confirm the potential use of this methodology to determine the best parameters to use in 3D fabrication for improving the effectiveness and stability of dental prostheses.