Probability density function (PDF) analysis with K-distribution model of optical coherence tomography (OCT) intensity signals has previously yielded a good representation of the average number of scatterers in a coherence volume for microspheres-in-water systems, and has shown initial promise for biological tissue characterization. In this work, we extend these previous findings, based on single point M-mode or 2D slice analysis, to full 3D imaging maps of the shape parameter α of the K-distribution PDF. After selecting a suitably-sized 3D evaluation window, and verifying methodology in phantoms the resultant parametric α images obtained in different animal tissues (rat liver and brain) show new ...

Background In vivo assessment of bioresorbable scaffold (BRS) is of growing clinical interest. The novel 60MHz high-definition intravascular ultrasound (HD-IVUS) has been developed to overcome the limitations of conventional 40 MHz IVUS. This study aimed to evaluate the performance and limitations of 60 MHz HD-IVUS compared with 40 MHz IVUS with respect to polymeric-strut visualization, quantitative and qualitative analysis, and feasibility of high-speed pullback in the assessment of BRS. Methods and Results In a bench-test model, 361 struts were analyzed to evaluate the influence of ultrasound-beam angles and proximity of adjacent struts on IVUS visualization of BRS struts. Various settings ...

Core-shell nanostructures associated with photonics techniques have found innumerous applications in diagnostics and therapy. In this work, we introduce a novel core-shell nanostructure design that serves as a multimodal optical imaging contrast agent for dental adhesion evaluation. This nanostructure consists of a rare-earth doped (NaYF 4 :Yb 60%,Tm 0.5%)/NaYF 4 particle as the core (hexagonal prism, ~51 nm base side length), and the highly refractive TiO 2 material as the shell (~thickness of 15 nm). We show that the TiO 2 shell provides enhanced contrast for Optical Coherence Tomography (OCT), while the rare-earth doped core upconverts excitation ...

A major challenge in biophotonics is multimodal imaging to obtain both morphological and molecular information at depth. We demonstrate a hybrid approach integrating optical coherence tomography (OCT) with wavelength modulated spatially offset Raman spectroscopy (WM-SORS). With depth co-localization obtained from the OCT, we can penetrate 1.2mm deep into the strong scattering media (lard) to acquire up to a 14-fold enhancement of a Raman signal from a hidden target (Polystyrene) with a spatial offset. Our approach is capable of detecting both Raman and OCT signals for pharmaceutical particles embedded in turbid media and revealing the white matter at depth within ...

Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress, and the diffusion coefficient of red blood cells (RBCs), are fundamental to understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic Light Scattering-Optical Coherence Tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained 3D volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT ...

In this observational and cross-sectional study, capillary non perfusion (CNP) and vascular changes in branch retinal vein occlusion (BRVO, sample size (n) = 26) and choroidal neovascularization (CNV, n = 29) were evaluated. Subjects underwent imaging using Optical coherence tomography angiography (Angiovue™ OCTA , RTVue XR, Optovue Inc., Fremont, CA). Local fractal analysis was applied to the OCTA images of superficial, deep and choriocapillaries layer. CNP area (BRVO eyes) and vascular parameters were computed using local fractal based method. Sensitivity and specificity of vascular parameters was assessed with receiver operating characteristics (ROC) curve. Automated CNP area showed excellent agreement with manually quantified CNP ...

Lymphatic dysfunction is involved in many diseases including lymphedema, hypertension, autoimmune responses, graft rejection, atherosclerosis, microbial infections, cancer and cancer metastasis. Expanding our knowledge of lymphatic system function can lead to a better understanding of these disease processes and improve treatment options. Here, optical coherence tomography (OCT) methods were used to reveal intraluminal valve dynamics in 3D, and measure lymph flow and vessel contraction simultaneously in three neighboring lymphangions of the afferent collecting lymphatic vessels to the popliteal lymph node in mice. Flow measurements were based on Doppler OCT techniques in combination with exogenous lymph labelling by Intralipid. Through these ...

Elastography has the ability of quantitatively evaluating the mechanical properties of soft tissue, thus is helpful for diagnosis and treatment monitoring for many diseases, e.g. skin diseases. Surface acoustic waves (SAWs) have been proven to be a non-invasive, non-destructive method for accurate characterization of tissue elastic properties. Current surface acoustic wave elastography using high energy laser pulse or mechanical shaker still have some problems. In order to improve SAW elastography in medical application, a new technique was proposed in this paper, which combines high intensity focused ultrasound (HIFU) as a SAWs impulse inducer and PhS-OCT as a SAWs detector ...

Objectives Culprit plaque characteristics in young patients who experience an Acute Coronary Syndrome (ACS) evaluated by OCT (Optical Coherence Tomography) have to be defined. The OCT-FORMIDABLE is a multicentre retrospective registry enrolling consecutive patients with ACS who performed OCT in 9 European centres. Methods Patients were divided in two groups according to age at presentation: juvenile-ACS (age ≤ 50 years) and not juvenile-ACS (age > 50 years). Primary end-point was the prevalence of plaque rupture (PR). Secondary end point was the prevalence of thin cap fibro atheroma (TCFA), fibrocalcific and fibrotic plaque. Results 285 patients were included, 71 (24.9%) in juvenile-ACS ...

Letter to the editor

Background/purpose Our objective was to assess epithelialization of suction blister lesions by optical coherence tomography (OCT) and benchmark it to histology using epidermal thickness (ET) as the primary outcome. Methods Thirty-two healthy volunteers were recruited to Study 1 and 2. One 10-mm suction blister was raised on each buttock, and the blister roof was excised. Lesions were covered with moisture-retaining dressing. In Study 1, the lesions were OCT-scanned on day 0 (D0), D2 and D4 and excised for histological examination. In Study 2, the progress of epithelialization and skin barrier function were monitored to D14. Results ET increased from ...

Importance Optical Coherence Tomography (OCT) is used routinely in management of diabetic eye disease but has not been evaluated in Australian outreach settings for screening programs. Background To evaluate the use of OCT combined with a fundus camera compared to a fundus camera only in a telehealth diabetic retinopathy (DR) screening program for Aboriginal Australians. Design Retrospective comparative study. Participants Patients with diabetes at two Aboriginal Health Services. Methods An intervention group was studied in 2015 using a Topcon 3D OCT-1 Maestro combined OCT/ fundus camera. A control group was studied in 2014 using a DRS non-mydriatic fundus camera. Fundus ...

Purpose To examine the capability of optical coherence tomography-derived retinal thickness measures in detecting 4-year incident diabetic peripheral neuropathy (DPN). Methods 145 eyes of 145 participants with diabetes but no DPN at baseline were examined for incident DPN. HbA 1c levels, nephropathy, neuropathy (DPN), cardiovascular measures, and various retinal thickness measures were examined at baseline and after 4 years. Incidence of DPN was defined as newly developed DPN at follow-up. Baseline factors were assessed by univariate and a step-wise multiple logistic regression, and the predictors were examined for diagnostic capabilities. Results Of the 145 participants without DPN at baseline, 51 ...

Purpose To investigate the reproducibility of Bruch's membrane opening minimum rim width (BMO-MRW) and retinal nerve fibre layer thickness (RNFLT) measurements using spectral domain optical coherence tomography (SD-OCT). Additionally, to investigate the reproducibility of BMO area measurements and fovea to BMO centre (FoBMO) angle. Methods Participants were healthy subjects ( n = 30) and patients with glaucoma ( n = 26). One eye of each participant was scanned to obtain optic nerve head (24 radial B-scans) and peripapillary (one circular B-scan) images by three independent examiners. Additionally, one examiner imaged each participant three times on the same day. Intra- and interobserver reproducibilities were ...

No abstract is available for this article.

Influence of diabetes mellitus (DM) and diabetic retinopathy (DR) on parafoveal retinal thicknesses and their ratios was evaluated. Six retinal layer boundaries were segmented from spectral-domain optical coherence tomography images using open-source software. Five study groups: (1) healthy control (HC) subjects, and subjects with (2) controlled DM, (3) uncontrolled DM, (4) controlled DR and (5) uncontrolled DR, were identified. The one-way analyses of variance (ANOVA) between adjacent study groups (i. e. 1 with 2, 2 with 3, etc) indicated differences in retinal thicknesses and ratios. Overall retinal thickness, ganglion cell layer (GCL) thickness, inner plexiform layer (IPL) thickness, and their ...

Most diagnostic testing in patients with anomalous aortic origins of coronary arteries, myocardial bridges, and coronary artery changes after Kawasaki disease are performed with the use of noninvasive techniques. In some cases, however, further diagnostic information is needed to guide the clinician in treating these patients. In such instances, cardiac catheterization with invasive anatomic and functional testing is an invaluable tool. Moreover, interventional treatment in the cardiac catheterization laboratory may be performed in a small subset of these patients. As the diagnosis of these conditions is now becoming more common, it is important for pediatric interventional cardiologists to be familiar ...

Background/Purpose The work outlined in this paper was aimed at achieving further understanding of skin frictional behaviour by investigating the contact area between human finger-pads and flat surfaces. Methods Both the static and the dynamic contact areas (in macro- and micro-scales) were measured using various techniques, including ink printing, optical coherence tomography (OCT) and Digital Image Correlation (DIC). Results In the studies of the static measurements using ink printing, the experimental results showed that the apparent and the real contact area increased with load following a piecewise linear correlation function for a finger-pad in contact with paper sheets. Comparisons ...

Purpose To investigate the macular microvasculature changes by optical coherence tomography angiography (OCTA) and analyse the correlation between these changes and central visual function in patients with retinitis pigmentosa (RP). Methods We measured the area of the foveal avascular zone (FAZ) and the foveal and parafoveal flow density (FFD and PFD, respectively) in the superficial (S) and deep (D) retinal plexus by OCTA (AngioVue) and compared these values between 73 RP patients and 36 healthy controls. We analysed the relationships between these microvasculature measurements and central visual functions such as visual acuity (VA) and the values of static perimetry tests ...

Imaging of biofilm systems is a prerequisite for a better understanding of both structure and its function. The review aims to critically discuss the use of optical coherence tomography (OCT) for the visualization of the biofilm structure as well as its dynamic behavior. A short overview on common and well-known, established imaging techniques for biofilms such as scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), Raman microscopy (RM), and magnetic resonance imaging (MRI) paves the way to imaging biofilms at the mesoscale, which is perfectly covered by means of OCT. Principle, resolution, imaging velocity, and limitations of OCT are ...

Background Acne vulgaris is a disease of the pilosebaceous unit, characterized by hyper-keratinization process, comedos formation and inflammatory reactions. Objective The definition of the morphology and the vascularization of acne lesions by means of dynamic optical coherence tomography (D-OCT), in order to non-invasively define the alterations occurring during the acne development and patient therapeutic management. Methods A set of standardized clinical pictures and D-OCT images were acquired from 114 acne lesions of 31 volunteers, presenting mild to moderate acne and evaluated by experts. Fifteen patients treated with oral antibiotics were followed during time at 0, 20, 40, and 60 days ...

Purpose The aim was to investigate the agreement for detection of progression of glaucomatous retinal nerve fibre layer defects (RNFLD) between optical coherence tomography-guided progression analysis (OCT GPA) and conventional red-free fundus photography. Methods Four hundred and fifteen glaucomatous eyes that underwent at least four serial red-free photographic and OCT examinations were included in the study. Based on the inspection of the red-free fundus photographs and GPA maps, RNFLD progression was defined as the development of a new defect, widening or deepening of a pre-existing RNFLD in red-free fundus photography (photographic progression) or ‘Likely Loss’ on a GPA map (GPA ...

Background/Purpose Full-field optical coherence tomography (FFOCT) is an emerging imaging technique for rapid histological analysis. As FFOCT is introduced into the Mohs workflow, it is important to document the effect of tissue freezing on FFOCT images and any effect FFOCT has on frozen sections. Our study aimed to evaluate the changes on FFOCT images after tissue freezing as well as FFOCT imaging effects on frozen sectioning. Methods Six normal skin specimens were imaged using FFOCT and subsequently frozen using a cryostat. The specimens were then reimaged using FFOCT and compared for any differences. To evaluate the effect of FFOCT ...