Limited Region Of Interest Research Articles

Optical Coherence Tomography Angiography as a Diagnostic Tool for Diabetic Retinopathy

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus, leading to visual impairment if left untreated. This review discusses the use of optical coherence tomography angiography (OCTA) as a diagnostic tool for the early detection and management of DR. OCTA is a fast, non-invasive, non-contact test that enables the detailed visualisation of the macular microvasculature in different plexuses. OCTA offers several advantages over fundus fluorescein angiography (FFA), notably offering quantitative data. OCTA is not without limitations, including the requirement for careful interpretation of artefacts and the limited region of interest that can be captured currently. We explore how OCTA has been instrumental in detecting early microvascular changes that precede clinical signs of DR. We also discuss the application of OCTA in the diagnosis and management of various stages of DR, including non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR), diabetic macular oedema (DMO), diabetic macular ischaemia (DMI), and pre-diabetes. Finally, we discuss the future role of OCTA and how it may be used to enhance the clinical outcomes of DR.

Atomistic and continuum length scale coupling in materials using quasicontinuum method

We propose coupling atomistic and continuum length scale models in materials to develop a multiscale modeling framework. High fidelity models like Molecular Dynamics and Density Functional Theory exist at atomic scales capable of explaining various small-scale occurrences. However, these models cannot be scaled up efficiently to explain a range of observations occurring at multiple length and time scales. Since continuum properties can be considered emergent from numerous smaller-scale phenomena, models capable of effectively relating multiple length and time scales are needed. Therefore, we propose using existing models at differing yet individual length scales and suitably coupling them for tackling such multiscale problems. This coupling method should facilitate information exchange in real-time and demonstrate rapid convergence without adding significant computational overhead. Together with single-scale models, this coupling could help us relate continuum properties like stiffness, damping, and thermal conductivity to a material's electronic structure and atomic arrangement. As an illustration, we choose a simple one-dimensional problem with a limited region of interest which we wish to study at an atomic scale. We rely upon the Quasicontinuum method to model this limited atomic region, which significantly reduces the degrees of freedom involved for the atomistic subdomain. Preliminary results for this static problem indicate that the displacement error is relevant on the atomic scale. Importance is put on deriving a method capable of effectively coupling atomic and continuum subdomains for solving general static or dynamic structural problems.

Revealing the Orbital Angular Momentum Spectrum and Correlation Phase of Optical Vortices With Wander Perturbations and Spiral Offsets

Controlling the orbital angular momentum (OAM) spectrum, as well as the modulus and phase of the first-order correlation function of a vortex beam produced by a dynamic wander source, is critical for the use of OAM photons in turbulent environments. Based on a derived analytical formula for the first-order correlation function of the light field, a theoretical model and an experimental approach are proposed for synthesizing and detecting complex wander vortex beams in the laboratory. Wander perturbations and spiral phase offsets are considered. The correlation phase and OAM spectrum of complex wander vortex beams are measured with a single spatial light modulator (SLM). The experimental results agree with the theoretical simulations and show that, given a limited region of interest, wander perturbations broaden the OAM spectrum asymmetrically with respect to the initial input mode, with a higher proportion of lower ordered non-signal modes than higher ordered modes. For a large spiral phase offset, the main peak of the OAM spectrum shifts away from the signal mode and toward a lower ordered side mode. Generation and measurement strategies have significant potential for free-space communication and remote sensing in turbulent environments.

Random motion nodes empowering opportunistic networks for smart cities

In this article we present an example of opportunistic networking system of communication for gathering and spreading information inside an urban area, trying to overcome obstacles to network efficacy.In this paper we consider a set of few terminals, not ever of the same type, in a smart city fractioned in zones that are interested in collecting the information originated from environment but possibly also other several sources by sensors, reading tags or communications. This set includes mobile nodes, two differently equipped type of them, pedestrian and vehicles, and fixed terminals. Also we aim to consider other nodes, for example also nodes with a completely random series of movements, regardless of their usefulness or natural real possibility.In particular, each terminal aims to retrieve the data items or environmental information in a limited region of interest (ROI). This is centred around the node position itself. The environment is supposed to be dynamic: data items may change over time. So all nodes must strive for updating or obtaining the latest data version. The objective of the paper is to evaluate the percentage of information each node gathers with policies based on a simple distributed data gathering and sharing through local broadcast communications. We study the diffusion of data items and information updates in the whole area, experimenting in different conditions the influence of adding to the scenario random motion of nodes. Some reflections are made so as that similar results may be obtained adding Unmanned Aerial Vehicles to a real urban scenario.The study we present in this paper has been done using computer simulation. We wrote a discrete event simulator working on the base of mobility and radio propagation traces obtained from the UDelModels tools.

Elastography in the Diagnosis of Non-Alcoholic Fatty Liver Disease

Currently, there has been a progressive increase in prevalence of one of the most common diffuse chronic liver diseases ― non-alcoholic fatty liver disease (NAFLD). Assessment of the stages of liver fibrosis and steatosis is prognostically significant in diagnosis of NAFLD. Routine diagnostic methods are either not able to accurately assess the severity of fibrosis and steatosis (ultrasound, laboratory tests), or cannot be used as a simple screening tool (liver biopsy) due to such limitations as invasiveness, dependence on pathologist qualification, high cost, and limited region of interest. Over the last two decades, the great progress has been made in non-invasive visualization of pathological changes in liver diseases. In this review, we examined the diagnostic characteristics of the most widely used non-invasive imaging methods in clinical practice, available for quantitative determination of fat and fibrosis in the liver: transient elastography with controlled attenuation parameter (CAP), acoustic radiation force impulse (ARFI) and shear wave elastography (SWE). Comparing these methods and their limitations, we came to conclusion, that elastographic methods (slightly more ARFI and SWE) are able to verify the F3, F4 stages of fibrosis in NAFLD with high sensitivity and specificity (90%); however, they are less accurate for early stages. Elastographic techniques have moderate accuracy in identifying the degree of steatosis due to the lack of uniform standardized cut-off values of CAP.

Performance issues in content dissemination to metropolitan mobile users

In this paper we consider a set of heterogeneous terminals in a urban area that are interested in collecting the information originated from several sources. This set includes mobile nodes (pedestrian and vehicles) and fixed terminals. In particular, each terminal aims at retrieving the data items in a limited region of interest (ROI) centered around the node position. Since data items may change over time all nodes must strive for having access to the latest version. The goal of the paper is to evaluate the amount of information each node is able to gather (coverage) resorting to simple distributed data collection and sharing through local broadcast communications. We study the diffusion of information updates in the whole area, evaluate the impact of energy saving policies in the protocol version run by pedestrian devices, and the impact of contextual awareness about location and motion of nodes in the forwarding policies. The study we present in this paper has been carried out through simulation. To this end we develop a discrete event simulator working on top of mobility and radio propagation traces obtained from the UDelModels tools that allow to obtain realistic traces of mobility and radio propagation.

Experimental evaluation of the resolution improvement provided by a silicon PET probe

A high-resolution PET system, which incorporates a silicon detector probe into a conventional PET scanner, has been proposed to obtain increased image quality in a limited region of interest. Detailed simulation studies have previously shown that the additional probe information improves the spatial resolution of the reconstructed image and increases lesion detectability, with no cost to other image quality measures. The current study expands on the previous work by using a laboratory prototype of the silicon PET-probe system to examine the resolution improvement in an experimental setting. Two different versions of the probe prototype were assessed, both consisting of a back-to-back pair of 1-mm thick silicon pad detectors, one arranged in 32 × 16 arrays of 1.4 mm × 1.4 mm pixels and the other in 40 × 26 arrays of 1.0 mm × 1.0 mm pixels. Each detector was read out by a set of VATAGP7 ASICs and a custom-designed data acquisition board which allowed trigger and data interfacing with the PET scanner, itself consisting of BGO block detectors segmented into 8 × 6 arrays of 6 mm × 12 mm × 30 mm crystals. Limited-angle probe data was acquired from a group of Na-22 point-like sources in order to observe the maximum resolution achievable using the probe system. Data from a Derenzo-like resolution phantom was acquired, then scaled to obtain similar statistical quality as that of previous simulation studies. In this case, images were reconstructed using measurements of the PET ring alone and with the inclusion of the probe data. Images of the Na-22 source demonstrated a resolution of 1.5 mm FWHM in the probe data, the PET ring resolution being approximately 6 mm. Profiles taken through the image of the Derenzo-like phantom showed a clear increase in spatial resolution. Improvements in peak-to-valley ratios of 50% and 38%, in the 4.8 mm and 4.0 mm phantom features respectively, were observed, while previously unresolvable 3.2 mm features were brought to light by the addition of the probe. These results support the possibility of improving the image resolution of a clinical PET scanner using the silicon PET-probe.

Defining the Optimal Region of Interest for Hyperemia Grading in the Bulbar Conjunctiva

Conjunctival hyperemia or conjunctival redness is a symptom that can be associated with a broad group of ocular diseases. Its levels of severity are represented by standard photographic charts that are visually compared with the patient's eye. This way, the hyperemia diagnosis becomes a nonrepeatable task that depends on the experience of the grader. To solve this problem, we have proposed a computer-aided methodology that comprises three main stages: the segmentation of the conjunctiva, the extraction of features in this region based on colour and the presence of blood vessels, and, finally, the transformation of these features into grading scale values by means of regression techniques. However, the conjunctival segmentation can be slightly inaccurate mainly due to illumination issues. In this work, we analyse the relevance of different features with respect to their location within the conjunctiva in order to delimit a reliable region of interest for the grading. The results show that the automatic procedure behaves like an expert using only a limited region of interest within the conjunctiva.

Three Dimensional Sound Field Reproduction using Multiple Circular Loudspeaker Arrays: Functional Analysis Guided Approach

Three dimensional sound field reproduction based on higher order Ambisonics requires the placement of loudspeakers on a sphere that surrounds the target reproduction region. The deployment of a spherical array is not trivial especially for implementation in real rooms where the placement flexibility is highly desirable. This paper proposes a design of multiple circular loudspeaker arrays for reproducing three dimensional sound fields originating from a limited region of interest. We apply a functional analysis framework to formulate the sound field reproduction problem in a closed form. Secondary source distributions and target sound fields are modeled as two Hilbert spaces and mapped by an integral operator and its adjoint operator, from which a self-adjoint operator is constructed and the singular value decomposition is applied to represent source distributions and sound fields with two sets of interrelated singular functions. We derive the solutions for a circular secondary source arrangement and propose the design of placing multiple circular loudspeaker arrays only over the limited region of interest. Such a design allows for non-spherical and non-uniform loudspeaker placement and thus provides a flexible array arrangement. The reproduction accuracy of the proposed method is verified through numerical simulations.

Lane Detection Based on Object Segmentation and Piecewise Fitting

A lane detection algorithm for complex environment was proposed. It was concerned on selecting candidate lane region by object segmentation. Then redundancy edges were extracted by Sobel operator. Furthermore, candidate lane markers were obtained by threshold selection from the edges. Finally lane markers were detected by piecewise fitting. The proposed algorithm was simulated in MATLAB. Experiments showed that lane markers could be detected correctly. Piecewise linear transformation in preprocessing has enhanced performance of detection while the environment was dim. And limited region of interest helps to identification lane in an appropriate region, which have the effect of enhancement in the speed of operation. Feature-based method is usually affected by intensity of image. Several characteristics of roads need to be considered in further for detection more precisely. DOI : http://dx.doi.org/10.11591/telkomnika.v12i5.3240

Algorithm of Lane Detection on an Appropriate Limited Region

This paper proposed a lane detection algorithm for urban environment. The algorithm was concerned on selecting an appropriate limited region of interest (ROI) by OTSU segmentation. Then candidates of lane markers were extracted by Canny, finally the lane boundaries were detected by Hough transform. The limited ROI helps to identification lane in an appropriate region. This process have the effect of enhancement in the speed of operation. The proposed algorithm was simulated in MATLAB. The test databases were shared by Fondazione Bruno Kessler (FBK). The experiments show that lane boundaries can be detected correctly although they are fade. Feature-based method is usually affected by intension of image. Several characteristics of roads need to be considered further for detection more precisely.

Active optical system for any field angle zoom

We have theoretically proposed a new type of active optical zoom system. It can change the magnification of an imaging system at any field angle, namely, it can change the effective focal length at a limited region of interest and simultaneously maintain high resolution. It is comprised of two static aspheric mirrors and two deformable mirrors; furthermore, by changing the curvature of mirrors the focal length can be adjusted from −399 to −558.6 mm. The system reduces the bandwidth of data transmission and may find potential applications in high speed photography.

The WiMap

As positioning technology is an important foundation of the Internet of Things, a dynamic indoor WLAN localization system is proposed in this paper. This paper mainly concentrates on the design and implementation of the WiMap-a dynamic indoor WLAN localization system, which employs grid-based localization method using RSS (received signal strength). To achieve high localization accuracy and low computational complexity, Gaussian mixture model is applied to approximate the signal distribution and a ROI (region of interest) is defined to limit the search region. The authors also discuss other techniques like AP selection and threshold control, which affects the localization accuracy. The experimental results indicate that an accuracy of 3m with 73.8% probability can be obtained in WiMap. Moreover, the running time is reduced greatly with limited ROI method.

Three-Dimensional Visualization of Immunological Processes of Entire Organs in Subcellular Resolution.

Abstract 61In vivo models of complex immune processes like stem cell engraftment, host-pathogen interactions or anti-tumor responses face the challenge to either provide dynamic information in low resolution (e.g. in vivo bioluminescence Imaging, BLI) or provide high resolution information with a limited field of view (e.g. multi-photon laser scanning microscopy/confocal microscopy).To overcome these limitations we applied a novel selective plane illumination microscopy (SPIM) technique (also termed ultramicroscopy), which enabled us to visualize structural and cellular changes in intact organs in high resolution. Here we investigated dynamic shifts at sites of graft-versus-host disease (GVHD) initiation in mice after allogenic hematopoietic cell transplantation (allo-HCT).For in vivo and ex vivo imaging we transplanted 1,2×106 luciferase+ DsRed+ transgenic C57Bl/6 T cells (H-2b, Thy1.1+) plus 5×106 bone marrow (BM) cells (H-2b, Thy1.2+) into myeloablative conditioned allogeneic Balb/c recipients (H-2d, Thy1.2+, 8 Gy) to induce aGVHD. Utilizing BLI we followed the development of GVHD in vivo. At the transition from GVHD initiation phase to effector phase (day+3 and day+4) we prepared the small bowel and Peyer‘s Patches (PPs) of allo-HCT recipients for whole organ microscopy and compared these to organs of untreated mice.Staining for T cell populations (CD4) and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) allowed us to visualize MAdCAM-1 expression in relation to T cell areas in whole PPs and surrounding intestinal mucosa (> 8mm3) in a high throughput format by creating approx. 1000 optical sections using multiple lasers and a sensitive CCD camera within 10 minutes. Adding another color channel revealed structural details through measurement of intrinsic autofluorescence. The individual color stacks were overlaid via computational image processing for three dimensional tissue reconstruction, volume measurements and quantification of protein expression.Ultramicroscopy exposed microanatomical structures like intestinal villi, crypts and PPs with its subepithelial dome regions and follicles by giving detailed information about MAdCAM-1 expressing blood vessels and T cell areas. The 3D reconstruction of small intestines in non-conditioned mice revealed that the MAdCAM-1 expression averaged at 1-2% of the entire PP and was predominantly restricted to the high endothelial venules (HEV). During the transition from the initiation to the effector phase of acute GVHD (day3-4) the overall MAdCAM-1 expression in PPs increased by 50fold. At this point MAdCAM-1 expression was also found in parafollicular and subepithelial cell populations, which still need to be characterized further concerning their lineage differentiation.MAdCAM-1 is well known as a vascular addressin molecule. Because of its importance in homing of α4β7+ T and B cell into the gastrointestinal tract we investigated the dynamic expression of MAdCAM-1 during acute GVHD within intact PPs. It is well established that MAdCAM-1 is an important regulator in the homing of α4β7+ T cell to PPs via HEVs. Additionally our data lead to the hypothesis that MAdCAM-1 might contribute to retain proliferating α4β7+ T cells during the initiation of an adaptive immune response and might support a synchronized exit of alloreactive T cells in the aGVHD effector phase.Conventional histological sections are labor intensive, time consuming and often restricted to a very limited region of interest and therefore, can result in missing rare events and under- or overestimation of biological processes. Ultramicroscopy helped us to overcome these limitations and enabled us to visualize immunological processes with subcellular resolution in whole organs.CB and MF, GSH and AB contributed equally to this work. Disclosures:No relevant conflicts of interest to declare.

Partial matching accuracy indices for shapes

AbstractIndices are proposed to measure the partial matching accuracy for outlines of shapes such as those identified only partially due to occlusion and with limited region of interest. The figure catching rate and the partial matching rate curves are defined. The fractional area under the curve represents effectively the matching accuracy. More intuitive indices are the catching and matching distances. The indices are illustrated with an example of application to evaluation of gastric outlines recognized in double‐contrast gastric radiograms. Gastric regions delineated by a computer are compared with tracings by a radiologist, in an attempt to evaluate numerically the accuracy. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(6): 50–58, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10550

Computing Voronoi skeletons of a 3-D polyhedron by space subdivision

We tackle the problem of computing the Voronoi diagram of a 3-D polyhedron whose faces are planar. The main difficulty with the computation is that the diagram's edges and vertices are of relatively high algebraic degrees. As a result, previous approaches to the problem have been non-robust, difficult to implement, or not provenly correct. We introduce three new proximity skeletons related to the Voronoi diagram: (1) the Voronoi graph (VG), which contains the complete symbolic information of the Voronoi diagram without containing any geometry; (2) the approximate Voronoi graph (AVG), which deals with degenerate diagrams by collapsing sub-graphs of the VG into single nodes; and (3) the proximity structure diagram (PSD), which enhances the VG with a geometric approximation of Voronoi elements to any desired accuracy. The new skeletons are important for both theoretical and practical reasons. Many applications that extract the proximity information of the object from its Voronoi diagram can use the Voronoi graphs or the proximity structure diagram instead. In addition, the skeletons can be used as initial structures for a robust and efficient global or local computation of the Voronoi diagram. We present a space subdivision algorithm to construct the new skeletons, having three main advantages. First, it solves at most uni-variate quartic polynomials. This stands in sharp contrast to previous approaches, which require the solution of a non-linear tri-variate system of equations. Second, the algorithm enables purely local computation of the skeletons in any limited region of interest. Third, the algorithm is simple to implement.