1. Articles from Andrew M. Rollins

    1-24 of 79 1 2 3 4 »
    1. SLIME: robust, high-speed 3D microvascular mapping

      SLIME: robust, high-speed 3D microvascular mapping

      Three dimensional (3D) microvascular imaging of cubic millimeter to centimeter size volumes often requires much time and expensive instruments. By combining optical clearing with a novel scatter-based optical coherence tomography (OCT) contrast agent, we have greatly extended OCT imaging depth in excised tissues while maintaining a simple and low cost approach that does not require in-depth OCT knowledge. The new method enables fast 3D microvascular mapping in large tissue volumes, providing a promising tool for investigating organ level microvascular abnormalities in large cohorts.

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    2. Noninvasive Assessment of Corneal Crosslinking With Phase-Decorrelation Optical Coherence Tomography

      Noninvasive Assessment of Corneal Crosslinking With Phase-Decorrelation Optical Coherence Tomography

      Purpose : There is strong evidence that abnormalities in corneal biomechanical play a causal role in corneal ectasias, such as keratoconus. Additionally, corneal crosslinking (CXL) treatment, which halts progression of keratoconus, directly appeals to corneal biomechanics. However, existing methods of corneal biomechanical assessment have various drawbacks: dependence on IOP, long acquisition times, or limited resolution. Here, we present a method that may avoid these limitations by using optical coherence tomography (OCT) to detect the endogenous random motion within the cornea, which can be associated with stromal crosslinking. Methods : Phase-decorrelation OCT (PhD-OCT), based in the theory of dynamic light scattering, is a ...

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    3. Complex regression Doppler optical coherence tomography

      Complex regression Doppler optical coherence tomography

      We introduce a new method to measure Doppler shifts more accurately and extend the dynamic range of Doppler optical coherence tomography (OCT). The two-point estimate of the conventional Doppler method is replaced with a regression that is applied to high-density B-scans in polar coordinates. We built a high-speed OCT system using a 1.68-MHz Fourier domain mode locked laser to acquire high-density B-scans (16,000 A-lines) at high enough frame rates (∼100  fps) to accurately capture the dynamics of the beating embryonic heart. Flow phantom experiments confirm that the complex regression lowers the minimum detectable velocity from 12.25  mm ...

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    4. Using optical coherence tomography to detect disturbances in coronary microvascular in a model of fetal alcohol syndrome

      Using optical coherence tomography to detect disturbances in coronary microvascular in a model of fetal alcohol syndrome

      Congenital coronary anomalies can result in severe consequences such as arrhythmias and sudden death. However, the etiology of abnormal embryonic coronary microvasculature development is understudied. Using a novel contrast-agent-based optical coherence tomography (OCT) technique, scatter labeled imaging of microvasculature in excised tissue (SLIME), we compared diseased and normal embryonic quail coronary microvasculature in 3D. Congenital heart defects associated with fetal alcohol syndrome (FAS) were induced in a quail model by injecting 40 uL of 50% ethanol solution into eggs during gastrulation. These and saline-injected quail eggs were incubated until stage 36. SLIME contrast agent was perfused through the aortas of ...

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    5. Imaging of Iris Lesions With High-Speed Optical Coherence Tomography

      Imaging of Iris Lesions With High-Speed Optical Coherence Tomography

      n BACKGROUND AND OBJECTIVES:To image and measure iris tumors with optical coherence tomography (OCT). n PATIENTS AND METHODS:High-speed(2,000– 4,000 axial-scan/sec and 4–16 frames/sec) 1.3-micron wavelength anterior segment OCT prototypes were used to image 6 eyes of 6 patients with a variety of iris lesions, including focal iris nevus, diffuse iris nevus, amelanotic iris nevus, iris melanocytosis, and iris melanoma. OCT images were compared with slit-lamp photography and ultrasound biomicroscopy. n RESULTS: OCT at 1.3-micron wavelength could penetrate the full thickness of the iris lesions and allow three-dimensional measurement of lesion ...

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    6. Complex decorrelation averaging in optical coherence tomography: a way to reduce the effect of multiple scattering and improve image contrast in a dynamic scattering medium

      Complex decorrelation averaging in optical coherence tomography: a way to reduce the effect of multiple scattering and improve image contrast in a dynamic scattering medium

      We demonstrate that complex decorrelation averaging can reduce the effect of multiple scattering and improve optical coherence tomography (OCT) imaging contrast. Complex decorrelation averaging calculates the product of an A-scan and the complex conjugate of a subsequent A-scan. The resultant signal is the product of the amplitudes and the phase difference. All these resulting complex signals at a particular location are then averaged. We take advantage of the fact that complex averaging, in contrast to conventional magnitude averaging, is sensitive to phase decorrelation. Sample motion that increases signal phase variance results in lower signal magnitude after complex averaging. Such motion ...

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    7. Simultaneous multimodal ophthalmic imaging using swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

      Simultaneous multimodal ophthalmic imaging using swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

      Scanning laser ophthalmoscopy (SLO) benefits diagnostic imaging and therapeutic guidance by allowing for high-speed en face imaging of retinal structures. When combined with optical coherence tomography (OCT), SLO enables real-time aiming and retinal tracking and provides complementary information for post-acquisition volumetric co-registration, bulk motion compensation, and averaging. However, multimodality SLO-OCT systems generally require dedicated light sources, scanners, relay optics, detectors, and additional digitization and synchronization electronics, which increase system complexity. Here, we present a multimodal ophthalmic imaging system using swept-source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography (SS-SESLO-OCT) for in vivo human retinal imaging. SESLO reduces the complexity ...

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    8. Processing to determine optical parameters of atherosclerotic disease from phantom and clinical intravascular optical coherence tomography three-dimensional pullbacks

      Processing to determine optical parameters of atherosclerotic disease from phantom and clinical intravascular optical coherence tomography three-dimensional pullbacks

      Analysis of intravascular optical coherence tomography (IVOCT) data has potential for real-time in vivo plaque classification. We developed a processing pipeline on a three-dimensional local region of support for estimation of optical properties of atherosclerotic plaques from coronary artery, IVOCT pullbacks. Using realistic coronary artery disease phantoms, we determined insignificant differences in mean and standard deviation estimates between our pullback analyses and more conventional processing of stationary acquisitions with frame averaging. There was no effect of tissue depth or oblique imaging on pullback parameter estimates. The method’s performance was assessed in comparison with observer-defined standards using clinical pullback data ...

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    9. Multimodal ophthalmic imaging using swept source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

      Multimodal ophthalmic imaging using swept source spectrally encoded scanning laser ophthalmoscopy and optical coherence tomography

      Scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT) benefit clinical diagnostic imaging in ophthalmology by enabling in vivo noninvasive en face and volumetric visualization of retinal structures, respectively. Spectrally encoding methods enable confocal imaging through fiber optics and reduces system complexity. Previous applications in ophthalmic imaging include spectrally encoded confocal scanning laser ophthalmoscopy (SECSLO) and a combined SECSLO-OCT system for image guidance, tracking, and registration. However, spectrally encoded imaging suffers from speckle noise because each spectrally encoded channel is effectively monochromatic. Here, we demonstrate in vivo human retinal imaging using a swept source spectrally encoded scanning laser ophthalmoscope and ...

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    10. Measurement Of Biomechanical Properties In An OCT Image

      Measurement Of Biomechanical Properties In An OCT Image

      Systems and method are provided for evaluating a biomechanical property of tissue. A shear wave generator is configured to induce a shear wave in the tissue. An optical coherence tomography (OCT) imager is configured to capture a B-scan frame of the tissue. An image processing component is configured to determine a frequency of the shear wave in the tissue from the B-scan frame of the tissue at each of a plurality of locations within the B-scan.

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    11. Characterizing Ablation Lesions Using Optical Coherence Tomography (OCT)

      Characterizing Ablation Lesions Using Optical Coherence Tomography (OCT)

      Systems, methods, and other embodiments associated with characterizing Radio Frequency Ablation (RFA) lesions using Optical Coherence Tomography (OCT) are described. One example method includes acquiring an OCT signal from a Region Of Interest (ROI) in an ablated material. The example method may also include determining whether a lesion was formed by the ablation by analyzing optical properties of the ROI as recorded in the OCT signal.

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    12. Mapping conduction velocity of early embryonic hearts with a robust fitting algorithm

      Mapping conduction velocity of early embryonic hearts with a robust fitting algorithm

      Cardiac conduction maturation is an important and integral component of heart development. Optical mapping with voltage-sensitive dyes allows sensitive measurements of electrophysiological signals over the entire heart. However, accurate measurements of conduction velocity during early cardiac development is typically hindered by low signal-to-noise ratio (SNR) measurements of action potentials. Here, we present a novel image processing approach based on least squares optimizations, which enables high-resolution, low-noise conduction velocity mapping of smaller tubular hearts. First, the action potential trace measured at each pixel is fit to a curve consisting of two cumulative normal distribution functions. Then, the activation time at each ...

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    13. 3-D Stent Detection in Intravascular OCT Using a Bayesian Network and Graph Search

      3-D Stent Detection in Intravascular OCT Using a Bayesian Network and Graph Search

      Worldwide, many hundreds of thousands of stents are implanted each year to revascularize occlusions in coronary arteries. Intravascular optical coherence tomography (OCT) is an important emerging imaging technique, which has the resolution and contrast necessary to quantitatively analyze stent deployment and tissue coverage following stent implantation. Automation is needed, as current, it takes up to 16 hours to manually analyze hundreds of images and thousands of stent struts from a single pullback. For automated strut detection, we used image formation physics and machine learning via a Bayesian network, and 3-D knowledge of stent structure via graph search. Graph search was ...

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    14. Intraoperative optical coherence tomography using an optimized reflective optical relay, real-time heads-up display, and semitransparent surgical instrumentation

      Intraoperative optical coherence tomography using an optimized reflective optical relay, real-time heads-up display, and semitransparent surgical instrumentation

      Ophthalmic surgical maneuvers are currently limited by the ability of surgeons to visualize and manipulate semitransparent tissue layers as thin as tens of microns. We describe several iterative advances in iOCT technology, including a novel iOCT system, real-time heads-up display (HUD) feedback, visualization of intraoperative maneuvers, and OCT-compatible surgical instrumentation. Simulated surgical maneuvers were performed on freshly enucleated porcine eyes. Subretinal space cannulation with injection was performed and imaged using spatial compounding. The optical properties of semitransparent materials were quantified to identify OCT-compatible substrates, and surgical instrument prototypes were machined, including corneal, surgical picks, and retinal forceps

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    15. Feature Of The Week 02/22/15: Case Western Reserve University Demostrates Using OCT to Rapidly Phenotype and Quantify Congenital Heart Defects Associated with Prenatal Alcohol Exposure

      Feature Of The Week 02/22/15:  Case Western Reserve University Demostrates Using OCT to Rapidly Phenotype and Quantify Congenital Heart Defects Associated with Prenatal Alcohol Exposure

      The most commonly used method to analyze congenital heart defects involves serial sectioning and histology. However, this is often a time-consuming process where the quantification of cardiac defects can be difficult due to problems with accurate section registration. Here we demonstrate the advantages of using optical coherence tomography, a comparatively new and rising technology, to phenotype avian embryo hearts in a model of Fetal Alcohol Syndrome where a binge-like quantity of alcohol/ethanol was introduced at gastrulation. The rapid, consistent imaging protocols allowed for the immediate identification of cardiac anomalies, including ventricular septal defects and misaligned/missing vessels. Interventricular septum ...

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    16. Parameter estimation of atherosclerotic tissue optical properties from three-dimensional intravascular optical coherence tomography

      Parameter estimation of atherosclerotic tissue optical properties from three-dimensional intravascular optical coherence tomography

      We developed robust, three-dimensional methods, as opposed to traditional A-line analysis, for estimating the optical properties of calcified, fibrotic, and lipid atherosclerotic plaques from in vivo coronary artery intravascular optical coherence tomography clinical pullbacks. We estimated attenuation μ t and backscattered intensity I 0 from small volumes of interest annotated by experts in 35 pullbacks. Some results were as follows: noise reduction filtering was desirable, parallel line (PL) methods outperformed individual line methods, root mean square error was the best goodness-of-fit, and α -trimmed PL ( α -T-PL) was the best overall method. Estimates of μ t were calcified ( 3.84 ± 0.95     mm − 1 ...

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    17. Using optical coherence tomography to rapidly phenotype and quantify congenital heart defects associated with prenatal alcohol exposure

      Using optical coherence tomography to rapidly phenotype and quantify congenital heart defects associated with prenatal alcohol exposure

      Background : The most commonly used method to analyze congenital heart defects involves serial sectioning and histology. However, this is often a time-consuming process where the quantification of cardiac defects can be difficult due to problems with accurate section registration. Here we demonstrate the advantages of using optical coherence tomography, a comparatively new and rising technology, to phenotype avian embryo hearts in a model of Fetal Alcohol Syndrome where a binge-like quantity of alcohol/ethanol was introduced at gastrulation. Results : The rapid, consistent imaging protocols allowed for the immediate identification of cardiac anomalies, including ventricular septal defects and misaligned/missing vessels ...

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    18. Capturing structure and function in an embryonic heart with biophotonic tools

      Capturing structure and function in an embryonic heart with biophotonic tools

      Disturbed cardiac function at an early stage of development has been shown to correlate with cellular/molecular, structural as well as functional cardiac anomalies at later stages culminating in the congenital heart defects (CHDs) that present at birth. While our knowledge of cellular and molecular steps in cardiac development is growing rapidly, our understanding of the role of cardiovascular function in the embryo is still in an early phase. One reason for the scanty information in this area is that the tools to study early cardiac function are limited. Recently developed and adapted biophotonic tools may overcome some of the ...

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    19. Differences determined by optical coherence tomography volumetric analysis in non-culprit lesion morphology and inflammation in ST-segment elevation myocardial infarction and stable angina pectoris patients

      Differences determined by optical coherence tomography volumetric analysis in non-culprit lesion morphology and inflammation in ST-segment elevation myocardial infarction and stable angina pectoris patients

      Background: While the current methodology for determining fibrous cap (FC) thickness of lipid plaques is based on manual measurements of arbitrary points, which could lead to high variability and decreased accuracy, it ignores the three-dimensional (3-D) morphology of coronary artery disease. Objective: To compare, utilizing optical coherence tomography (OCT) assessments, volumetric quantification of FC and macrophage detection using both visual assessment and automated image processing algorithms in non-culprit lesions of STEMI and stable angina pectoris (SAP) patients. Methods: Lipid plaques were selected from 67 consecutive patients (1 artery/patient). FC was manually delineated by a computer-aided method and automatically classified ...

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    20. Fiber-optic catheter-based polarization-sensitive OCT for radio-frequency ablation monitoring

      Fiber-optic catheter-based polarization-sensitive OCT for radio-frequency ablation monitoring

      An all-fiber optic catheter-based polarization-sensitive optical coherence tomography system is demonstrated. A novel multiplexing method was used to illuminate the sample, splitting the light from a 58.5 kHz Fourier-domain mode-locked laser such that two different polarization states, alternated in time, are generated by two semiconductor optical amplifiers. A 2.3 mm forward-view cone-scanning catheter probe was designed, fabricated, and used to acquire sample scattering intensity and phase retardation images. The system was first verified with a quarter-wave plate and then by obtaining intensity and phase retardation images of high-birefringence plastic, human skin in vivo , and untreated and thermally ablated ...

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    21. Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

      Three-dimensional correction of conduction velocity in the embryonic heart using integrated optical mapping and optical coherence tomography

      Optical mapping (OM) of cardiac electrical activity conventionally collects information from a three-dimensional (3-D) surface as a two-dimensional (2-D) projection map. When applied to measurements of the embryonic heart, this method ignores the substantial and complex curvature of the heart surface, resulting in significant errors when calculating conduction velocity, an important electrophysiological parameter. Optical coherence tomography (OCT) is capable of imaging the 3-D structure of the embryonic heart and accurately characterizing the surface topology. We demonstrate an integrated OCT/OM imaging system capable of simultaneous conduction mapping and 3-D structural imaging. From these multimodal data, we obtained 3-D activation maps ...

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    22. Serial biomechanical comparison of edematous, normal, and collagen crosslinked human donor corneas using optical coherence elastography

      Serial biomechanical comparison of edematous, normal, and collagen crosslinked human donor corneas using optical coherence elastography

      Purpose To noninvasively evaluate the effects of corneal hydration and collagen crosslinking (CXL) on the mechanical behavior of the cornea. Setting Cleveland Clinic Cole Eye Institute, Cleveland, Ohio, USA. Design Experimental study. Methods An optical coherence elastography (OCE) technique was used to measure the displacement behavior of 5 pairs of debrided human donor globes in 3 serial states as follows: edematous, normal thickness, and after riboflavin–ultraviolet-A–mediated CXL. During micromotor-controlled axial displacements with a curved goniolens at physiologic intraocular pressure (IOP), serial optical coherence tomography scans were obtained to allow high-resolution intrastromal speckle tracking and displacement measurements over the ...

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    23. Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects?

      Ethanol exposure alters early cardiac function in the looping heart: a mechanism for congenital heart defects?

      Alcohol-induced congenital heart defects (CHDs) are frequently among the most life-threatening and require surgical correction in newborns. The etiology of these defects, collectively known as Fetal Alcohol Syndrome (FAS), has been the focus of much study, particularly involving cellular and molecular mechanisms. Few studies have addressed the influential role of altered cardiac function in early embryogenesis, due to a lack of tools with the capability to assay tiny beating hearts. To overcome this gap in our understanding, we used optical coherence tomography (OCT), a non-destructive imaging modality capable of micrometer-scale resolution imaging, to rapidly and accurately map cardiovascular structure and ...

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    24. Feature Of The Week 1/20/13: CWRU Demonstrates Automatic Stent Detection in Intravascular OCT Images Using Bagged Decision Trees

      Feature Of The Week 1/20/13: CWRU Demonstrates Automatic Stent Detection in Intravascular OCT Images Using Bagged Decision Trees

      Cardiovascular disease is the leading cause of death worldwide. Stent implantation by means of percutaneous coronary intervention is the most common coronary revascularization procedure. Intravascular Optical Coherence Tomography (iOCT) is the only imaging modality with the resolution and contrast necessary to enable accurate measurements of luminal architecture and neointima stent coverage. Manual analysis of intravascular OCT pullbacks is time consuming, limiting the size and number of studies that can be performed. We developed a highly automated method for detecting stent struts and measuring tissue coverage. Candidate struts were first identified using image processing techniques. We trained a bagged decision trees ...

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    1-24 of 79 1 2 3 4 »
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