ABSTRACT
The foveal avascular zone(FAZ)is the most sensitive region of the retina, which is interconnected by the macular capillary plexus. Its morphology can indirectly reflect the alterations of macular microcirculation. With strong repeatability and reliability, optical coherence tomography angiography(OCTA)can non-invasively visualize and quantify the FAZ. The great value of OCTA makes it an important supplemental examination tool in ophthalmology and other professions. The area and perimeter of FAZ have been demonstrated to be an effective clinical diagnostic indicator in high myopia, diabetic retinopathy, glaucoma and other ocular diseases. In recent years, the geometry of FAZ has also proven to have clinical value. The parameters describing the geometry of FAZ, such as circularity index, acircularity index and axial ratio, provide a new perspective for ocular disease research. The comprehensive investigation of the morphological characteristics of the FAZ is helpful to explore the pathological mechanism of the occurrence and development of ocular diseases, predict preclinical changes, make pathological stages of the disease precise, and provide a theoretical basis for monitoring the disease's progression and assessing patients' visual prognosis.
ABSTRACT
Aims and Objectives: Mild and/or moderate ischemic mitral regurgitation (IMR) may resolve after isolated coronary artery bypass grafting (CABG). It has been shown that the loss of saddle shape of the mitral valve is associated with IMR and is determined by an increase in the nonplanarity angle (NPA). The aim of this prospective, observational study was to test the hypothesis that NPA might decrease immediately after CABG alone in patients with mild to moderate IMR. Materials and Methods: This prospective, observational study was conducted in an academic, tertiary care hospital. Twenty patients underwent 2D and 3D transoesophageal echocardiography (TEE) and mitral valve assessment before and immediately after the CABG. NPA, circularity index, and other geometric variables were obtained. They were compared using paired t test. The SPSS (Version 15.0, Chicago, IL, USA) was used for statistical analysis. P <0.05 was considered significant. Results: The NPA was similar in the pre- and post-bypass periods (148° ± 15°, 148° ± 19°, P = 0.88). Circularity index (0.93 ± 0.13, 0.97 ± 0.11, P = 0.41) also was similar. Conclusions: There was no change in the mitral valve NPA with revascularization alone in patients with mild or moderate IMR. Mitral valve does not change its planarity (NPA) with revascularization alone in patients with IMR.
Subject(s)
Coronary Artery Bypass/methods , Echocardiography, Three-Dimensional/methods , Echocardiography, Transesophageal/methods , Humans , Mitral Valve/anatomy & histology , Mitral Valve/physiopathology , Mitral Valve/diagnostic imaging , Mitral Valve Insufficiency/etiology , Mitral Valve Insufficiency/diagnostic imaging , Myocardial Revascularization/methods , Patients , Percutaneous Coronary Intervention/methodsABSTRACT
This study presents a methodological approach based on radar images and on gray level, size and geometric pattern to identify potential unofficial airplane strips in Amazonia. The following procedures were conducted: georeferencing of a L-band, HH polarization, 3-meter spatial resolution image obtained by the SAR-R99B system over the Itaituba municipality, State of Para; subtraction of speckle noise with a median filter; image classification with the ISODATA unsupervised technique; conversion of selected targets of interest into vector format; and calculation and automatic selection of targets of interest by the circularity and tortuosity indices. Among the 10 previously identified targets, two were considered as potential unofficial airplane strips by the above mentioned indices.
Este estudo apresenta uma abordagem metodológica baseada em imagens de radar e nos critérios de tonalidade, tamanho e forma geométrica para identificar prováveis pistas de pouso não-homologadas na Amazônia. Os seguintes procedimentos foram conduzidos: georreferenciamento da imagem do sensor SAR-R99B do município paraense de Itaituba, adquirida na banda L, polarização HH e resolução espacial de três metros; subtração do ruído speckle com filtro mediana; classificação com a técnica não-supervisionada ISODATA; vetorização da classe indicativa dos alvos de interesse; e cálculo e seleção automática dos alvos de interesse por critérios de índice de circularidade e de tortuosidade. Foram identificados dez alvos, dos quais dois foram considerados como prováveis pistas de pouso pelos referidos índices.