Current Issue : October - December Volume : 2013 Issue Number : 4 Articles : 4 Articles
Background: Atherosclerotic plaque is subjected to a repetitive deformation due to\r\narterial pulsatility during each cardiac cycle and damage may be accumulated over a\r\ntime period causing fibrous cap (FC) fatigue, which may ultimately lead to rupture. In\r\nthis study, we investigate the fatigue process in human carotid plaques using in vivo\r\ncarotid magnetic resonance (MR) imaging.\r\nMethod: Twenty seven patients with atherosclerotic carotid artery disease were\r\nincluded in this study. Multi-sequence, high-resolution MR imaging was performed\r\nto depict the plaque structure. Twenty patients were found with ruptured FC or\r\nulceration and 7 without. Modified Paris law was used to govern crack propagation\r\nand the propagation direction was perpendicular to the maximum principal stress at\r\nthe element node located at the vulnerable site.\r\nResults: The predicted crack initiations from 20 patients with FC defect all matched\r\nwith the locations of the in vivo observed FC defect. Crack length increased rapidly\r\nwith numerical steps. The natural logarithm of fatigue life decreased linearly with the\r\nlocal FC thickness (R2 = 0.67). Plaques (n=7) without FC defect had a longer fatigue\r\nlife compared with those with FC defect (p = 0.03).\r\nConclusion: Fatigue process seems to explain the development of cracks in FC,\r\nwhich ultimately lead to plaque rupture....
Introduction: This paper presents the problem of automatic measurement of the\r\niridocorneal angle in tomographic images of the anterior segment of the eye. It\r\nincludes the results of the comparison of well-known methods for measuring the\r\niridocorneal angle with new methods, proposed in this paper. All these methods\r\nconcern tomographic image analysis and processing.\r\nMaterial and method: In total, approximately 100�000 tomographic images (from\r\nabout 6�000 patients) were analysed. They were obtained using two devices: SOCT\r\nCopernicus (Optopol Tech. SA, Zawiercie, Poland) and Visante OCT (Carl Zeiss\r\nMeditec, Inc, Dublin, California, USA). The patients, aged 12 to 78 years with varying\r\ndegrees of the iridocorneal angle pathology, were from the region of Silesia, Poland.\r\nThe images were in DICOM or RAW formats and analysed in the software developed\r\nby the authors for the purposes of this study.\r\nResults: The results indicate that the measurement method proposed by the\r\nauthors, which is based on the calculation of the minimum distance between the iris\r\nand the cornea in the adopted area, is the most accurate. For this method sensitivity\r\nwas 0.88, specificity 0.89 and the area under the Receiver Operating Characteristic\r\ncurve (AUC) was 0.88. The other known methods for measuring the iridocorneal\r\nangle gave worse results, that is, for example, for the measurement of the distance\r\nbetween the iris and the cornea AUC = 0.87, sensitivity = 0.86 and specificity = 0.71.\r\nFor another well-known method of measuring the iridocorneal angle AUC = 0.77,\r\nsensitivity = 0.82 and specificity = 0.61.\r\nConclusions: The study proved that the proposed method of measuring the\r\nminimum distance between the iris and the cornea within the adopted area is the\r\nmost effective in the classification of the iridocorneal angle in patients with a high\r\ndegree of pathology of all the compared measurement methods based on\r\ntomographic images. However, it requires fully automated measurement....
Optical imaging techniques reflect different biochemical processes in the brain,\r\nwhich is closely related with neural activity. Scientists and clinicians employ a variety\r\nof optical imaging technologies to visualize and study the relationship between\r\nneurons, glial cells and blood vessels. In this paper, we present an overview of the\r\ncurrent optical approaches used for the in vivo imaging of neurovascular coupling\r\nevents in small animal models. These techniques include 2-photon microscopy, laser\r\nspeckle contrast imaging (LSCI), voltage-sensitive dye imaging (VSDi), functional\r\nphotoacoustic microscopy (fPAM), functional near-infrared spectroscopy imaging\r\n(fNIRS) and multimodal imaging techniques. The basic principles of each technique\r\nare described in detail, followed by examples of current applications from cuttingedge\r\nstudies of cerebral neurovascular coupling functions and metabolic. Moreover,\r\nwe provide a glimpse of the possible ways in which these techniques might be\r\ntranslated to human studies for clinical investigations of pathophysiology and\r\ndisease. In vivo optical imaging techniques continue to expand and evolve, allowing\r\nus to discover fundamental basis of neurovascular coupling roles in cerebral\r\nphysiology and pathophysiology....
Background: Intravascular ultrasound (IVUS) is a standard imaging modality for\r\nidentification of plaque formation in the coronary and peripheral arteries. Volumetric\r\nthree-dimensional (3D) IVUS visualization provides a powerful tool to overcome the\r\nlimited comprehensive information of 2D IVUS in terms of complex spatial\r\ndistribution of arterial morphology and acoustic backscatter information.\r\nConventional 3D IVUS techniques provide sub-optimal visualization of arterial\r\nmorphology or lack acoustic information concerning arterial structure due in part to\r\nlow quality of image data and the use of pixel-based IVUS image reconstruction\r\nalgorithms. In the present study, we describe a novel volumetric 3D IVUS\r\nreconstruction algorithm to utilize IVUS signal data and a shape-based nonlinear\r\ninterpolation.\r\nMethods: We developed an algorithm to convert a series of IVUS signal data into a\r\nfully volumetric 3D visualization. Intermediary slices between original 2D IVUS slices\r\nwere generated utilizing the natural cubic spline interpolation to consider the\r\nnonlinearity of both vascular structure geometry and acoustic backscatter in the\r\narterial wall. We evaluated differences in image quality between the conventional\r\npixel-based interpolation and the shape-based nonlinear interpolation methods\r\nusing both virtual vascular phantom data and in vivo IVUS data of a porcine femoral\r\nartery. Volumetric 3D IVUS images of the arterial segment reconstructed using the\r\ntwo interpolation methods were compared.\r\nResults: In vitro validation and in vivo comparative studies with the conventional\r\npixel-based interpolation method demonstrated more robustness of the shape-based\r\nnonlinear interpolation algorithm in determining intermediary 2D IVUS slices. Our\r\nshape-based nonlinear interpolation demonstrated improved volumetric 3D\r\nvisualization of the in vivo arterial structure and more realistic acoustic backscatter\r\ndistribution compared to the conventional pixel-based interpolation method.\r\nConclusions: This novel 3D IVUS visualization strategy has the potential to improve\r\nultrasound imaging of vascular structure information, particularly atheroma\r\ndetermination. Improved volumetric 3D visualization with accurate acoustic\r\nbackscatter information can help with ultrasound molecular imaging of atheroma\r\ncomponent distribution....
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