Letter to the editor. 

Letter to the Editor.

Comparing 3D structural information obtained by optical coherence tomography (OCT) requires accurate alignment of images acquired from individual subjects. Despite the widespread use of OCT to image the anterior and posterior mouse eye, few approaches to align the resulting image data have been described, in part due to a lack of well-characterized landmarks that are suitable for alignment. Here, we provide an OCT acquisition and analysis protocol that incorporates the use of the long posterior ciliary arteries as landmarks. In mammals, these two large choroidal vessels lie in a plane approximately parallel to the horizon. Our OCT imaging approach resolves ...

Background Multiple sclerosis (MS) associated optic neuritis (MSON) causes atrophy of the inner retinal layers, which can be quantified by optical coherence tomography (OCT). It has been suggested that the Inter-Eye Percentage Difference (IEPD) of atrophy may be of diagnostic value in MSON. Methods Prospective, cross-sectional study in MS patients and healthy controls (HC). Spectral-domain OCT of both eyes was performed, followed by automated retinal layer segmentation of the peripapillary retinal nerve fibre layer (pRNFL) and macular ganglion cell and inner plexiform layer (mGCIPL). Receiver Operator Characteristics Curves were plotted and the area under the curve (AUC) was calculated for ...

Background FFA is a cicatricial alopecia that affects the frontotemporal hairline, eyebrows, and body hair. OCT is a non-invasive imaging technique useful in understanding skin architecture and vascularization. Objective To describe structural and vascular findings in FFA using OCT. Methods This was a case-control study conducted from the months of December 2016-February 2017. The study was IRB approved and conducted at the University of Miami Hospital outpatient dermatology hair and nail clinic in Miami, FL. Four patients with biopsy proven FFA, and three healthy age and sex-matched controls participated. OCT scans were taken on cicatricial alopecic band, inflammatory hairline, eyebrow ...

This paper reports a handheld multiphoton fluorescence microscope designed for clinical imaging that incorporates axial motion compensation and lateral image stabilization. Spectral domain optical coherence tomography is employed to track the axial position of the skin surface, and lateral motion compensation is realised by imaging the speckle pattern arising from the optical coherence tomography beam illuminating the sample. Our system is able to correct lateral sample velocities of up to ~65 μm s -1 . Combined with the use of negative curvature microstructured optical fibre to deliver tunable ultrafast radiation to the handheld multiphoton scanner without the need of a dispersion ...

Objective Children with Leber congenital amaurosis (LCA) due to CEP290 mutations show characteristic macular preservation. Spectral domain-optical coherence tomography (SD-OCT) is a noninvasive technique to investigate retinal structural changes. Loss of integrity of the ellipsoid zone (EZ) on OCT in people with retinal disease has been associated with loss of visual function and is a useful measure of retinal disease progression. We hypothesized that rdAc felines with Cep290 mutation would have a similar pattern of degeneration, with relative central retinal preservation associated with maintenance of the EZ. Procedures Fundus imaging, confocal scanning laser ophthalmoscopy, and SD-OCT cross-sectional imaging was performed ...

A novel machine-learning method to distinguish between tumor and normal tissue in optical coherence tomography (OCT) has been developed. Pre-clinical murine ear model implanted with mouse colon carcinoma CT-26 was used. Structural-image-based feature sets were defined for each pixel and machine learning classifiers were trained using “ground truth” OCT images manually segmented by comparison with histology. The accuracy of the OCT tumour segmentation method was then quantified by comparing with fluorescence imaging of tumors expressing genetically encoded fluorescent protein KillerRed that clearly delineates tumor borders. Since the resultant 3D tumor/normal structural maps are inherently co-registered with OCT derived maps ...

Background The shear stress distribution assessment can provide useful insights for the hemodynamic performance of the implanted stent/scaffold. Our aim was to investigate the effect of a novel bioresorbable scaffold, Mirage on local hemodynamics in animal models. Method The main epicardial coronary arteries of 7 healthy mini-pigs were implanted with 11 Mirage Microfiber sirolimus-eluting Bioresorbable Scaffolds (MMSES). Optical coherence tomography (OCT) was performed post scaffold implantation and the obtained images were fused with angiographic data to reconstruct the coronary artery anatomy. Blood flow simulation was performed and Endothelial Shear Stress(ESS) distribution was estimated for each of the 11 ...

Our ability to detect neoplastic changes in gastrointestinal (GI) tracts is limited by the lack of an endomicroscopic imaging tool that provides cellular-level structural details of GI mucosa over a large tissue area. In this paper, we report a fiber-optic based micro-optical coherence tomography (μOCT) system and demonstrate its capability to acquire cellular-level details of GI tissue through circumferential scanning. The system achieves an axial resolution of 2.48 µm in air and a transverse resolution of 4.8 µm with a depth-of-focus (DOF) of ~150 µm. To mitigate the issue of limited DOF, we used a rigid sheath to ...

Background and Objective Surgical oncology can benefit from specialized tools that enhance imaging and enable precise cutting and removal of tissue without damage to adjacent structures. The combination of high-resolution, fast optical coherence tomography (OCT) co-aligned with a nanosecond pulsed thulium (Tm) laser offers advantages over conventional surgical laser systems. Tm lasers provide superior beam quality, high volumetric tissue removal rates with minimal residual thermal footprint in tissue, enabling a reduction in unwanted damage to delicate adjacent sub-surface structures such as nerves or micro-vessels. We investigated such a combined Tm/OCT system with co-aligned imaging and cutting beams—a configuration ...

Background Dynamic optical coherence tomography (D-OCT) has recently been introduced in dermatology. In contrast to ‚Standard’ OCT imaging, which exclusively relies on the morphological analysis of the tissue, D-OCT allows the in-vivo visualisation of blood flow. Preliminary D-OCT data showed differences in the vascularisation of nevus to melanoma transition, suggesting that this technology may help to differentiate between benign and malignant lesions. Objective Several factors may influence the quality of D-OCT imaging. Therefore, standard operating procedures as well as a common terminology are required for better validation and comparison of the images. Methods Here we present practical guidelines for optimal ...

Background Skin biopsies only provide point-in-time data making longitudinal studies difficult. Using Dynamic optical coherence tomography (D-OCT) in vivo , non-invasive imaging of the microvasculature becomes possible. The current OCT literature is almost exclusively based on qualitative information but quantitative data may offer additional advantages, for example, by reducing observer variation. The objective of this study was to evaluate the in vivo superficial distribution of blood vessels, defined as the surface-to-first-vessel distance, in actinic keratosis, basal cell carcinoma, squamous cell carcinoma and normal skin. Methods D-OCT images of 52 histologically verified lesions and corresponding normal skin were included. The dataset consisted ...

Background: Since the advent of robotic-assisted surgery, the value of using robotic systems to assist in surgical procedures has been repeatedly demonstrated. However, existing technologies are unable to perform complete, multi-step procedures from start to finish. Many intraocular surgical steps continue to be manually performed. Methods: An intraocular robotic interventional surgical system (IRISS) capable of performing various intraocular surgical procedures was designed, fabricated, and evaluated. Methods were developed to evaluate the performance of the remote centers of motion (RCMs) using a stereo-camera setup and to assess the accuracy and precision of positioning the tool tip using an optical coherence tomography ...

OCT (optical coherence tomography) of corneal layers was generated to analyze the remodeling of the epithelium and stroma after photorefractive keratectomy (PRK). Myopic PRK was performed in 15 patients. One eye underwent manual scraping of epithelium while the other was treated with Epi clear. Epi clear allowed a gentler removal of the epithelium compared to manual scraping. Scheimpflug (Pentacam, OCULUS Optikgerate Gmbh, Wetzlar, Germany) and OCT (RTVue, Optovue Inc., Fremont, California, USA) scans of the cornea were performed before and after PRK (3 months). The OCT scanner and Pentacam acquired 8 and 25 radial 2-D scans of the cornea, respectively ...

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 ...