Three-dimensional reconstruction of stenosed coronary artery segments with assessment of the flow impedance

In this paper preliminary results of a study about the diagnostic benefits of 3D visualization and quantitation of stenosed coronary artery segments are presented. As is well known, even biplane angiographic images do not provide enough information for binary reconstruction. Therefore,a priori information about the slice to be reconstructed must be incorporated into the reconstruction algorithm. One approach is to assume a circular cross-section of the coronary artery. Hence, the diameter is estimated from the contours of the vessels in both projections. Another approach is to search for a solution of the reconstruction problem close to the previously reconstructed adjacent slice. In this paper we follow the first method based on contour information. The reconstructed coronary segment is visualized in three dimensions. Based on the obtained geometry of the obstruction the pertinent blood flow impedance is estimated on the basis of fluid dynamic principles. The results of applying the reconstruction algorithms to clinical coronary biplane exposures are presented with an indication of the assessed flow impedance

A Three dimensional spatial reconstruction of the left ventricle and analysis of ventricular geometry / by Nicola L. Fazzalari

This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legalsThesis--University of Adelaide, Dept. of Pathology, 198

ENHANCING THE EFFICIENCY OF THE LEVENSHTEIN DISTANCE BASED HEURISTIC METHOD OF ARRANGING 2D APICTORIAL ELEMENTS FOR INDUSTRIAL APPLICATIONS

The article addresses the challenge of reconstructing 2D broken pictorial objects by automating the search for matching elements, which is particularly relevant in fields like archaeology and forensic science. The authors propose a method to match such elements and streamline the search process by detecting and filtering out low quality matches. The study delves into optimizing the search process in terms of duration and assembly quality. It examines factors like comparison window length, Levenshtein measure margin, and number of variants to check, using theoretical calculations and experiments on synthetic elements. The experimental results demonstrate enhanced method effectiveness, yielding more useful solutions and significantly reducing the complexity of element comparisons by up to 100 times in extreme cases

Optimization and reconstruction of hv-convex (0,1)-matrices

AbstractWe consider a variant of the NP-hard problem of reconstructing hv-convex (0,1)-matrices from known row and column sums. Instead of requiring the ones to occur consecutively in each row and column, we maximize the number of neighboring ones. This is reformulated as an integer programming problem. A solution method based on variable splitting is proposed and tested with good results on moderately sized test problems

3D reconstruction of coronary arteries from angiographic sequences for interventional assistance

Introduction -- Review of literature -- Research hypothesis and objectives -- Methodology -- Results and discussion -- Conclusion and future perspectives

Image processing techniques in nuclear medicine

The application of image processing techniques to radionuclide images acquired on a gamma camera - computer system has been investigated. Hepatic perfusion imaging studies with 99Tcm-tin colloid were performed in patients with primary colorectal carcimma. The hepatic perfusion index performed poorly in the detection of those patients with occult or overt hepatic metastastes, as did mean transit times of liver colloid flow derived from deconvolution analysis. A discriminant function was developed which separated those patients with occult metastases from those without liver disease. A fully automatic algorithm to derive a left ventricular edge from each frame of an ECG gated cardiac blood pool study was developed and validated in patient studies. Left ventricular ejection fractions calculated from count rates within the edge were reproducible and correlated well with ejection fractions derived from the same images by a manual technique, and with ejection fractions derived from left ventricular cineangiography. Studies were performed in patients to evaluate the effectiveness of tomographic imaging of the myocardial perfusion imaging agent 99Tcm-tBIN for detection of ischaemic heart disease. Tomographic reconstructions in the planes of the axes of the left ventricle gave better results than transaxial reconstructions or planar imaging. Choice of the optimum reconstruction filter for use in tomography using 99Tcm-tBIN was examined by means of patient am phantom studies. These showed that more accurate diagnoses and better reconstructions were obtained with smoothing filters than by the use of sharp reconstruction filters. This work shows that optimum image processing techniques must be established to attain the best possible results with new radiopharmaceuticals for nuclear medicine investigations

Contributions to imaging.

Four topics are considered - each associated with a different aspect of imaging. Using X-ray diffraction it is possible to say much about the structure of molecules. Two models for the D.N.A. molecule are analysed with respect to the diffraction data. The models are Watson and Crick's "Double Helix" and Rodley's, recently developed, "Side-by-Side". It is demonstrated that the side-by-side is a viable alternative model for D.N.A. However the low quality of the data precludes a definitive decision as to the actual structure of the molecule. Conventional X-ray computed tomography body scanners, while producing impressive results when imaging stationary objects, can not image rapidly moving organs such as the beating heart. As the heart motion is periodic, it has been suggested that stroboscopic techniques be employed. However the resulting imaging quality is poor when standard image reconstruction methods are used. By taking account of the fact that the region surrounding the heart is stationary, though, a significant improvement in image quality can be obtained. A simple procedure for achieving this improvement is presented here. Ultrasonic transmission tomography is more complicated than the X-ray case because ultrasonic rays, unlike X-rays, are diffracted as they pass through a body. Therefore they are generally curved. It is shown how ray curvature makes it impossible to image certain types of objects exactly. Nevertheless it seems that useful results can be obtained by treating the rays as being straight, and using X-ray computed tomography image reconstruction algorithms. Imaging using electric currents is examined. The types of independent measurements that can be made are discussed. The imaging problem is far from. trivial and, in the general case, largely unsolved. Here a method for uniquely imaging circularly symmetric conductivity distributions is outlined

Coronary Artery Segmentation and Motion Modelling

Conventional coronary artery bypass surgery requires invasive sternotomy and the use of a cardiopulmonary bypass, which leads to long recovery period and has high infectious potential. Totally endoscopic coronary artery bypass (TECAB) surgery based on image guided robotic surgical approaches have been developed to allow the clinicians to conduct the bypass surgery off-pump with only three pin holes incisions in the chest cavity, through which two robotic arms and one stereo endoscopic camera are inserted. However, the restricted field of view of the stereo endoscopic images leads to possible vessel misidentification and coronary artery mis-localization. This results in 20-30% conversion rates from TECAB surgery to the conventional approach. We have constructed patient-specific 3D + time coronary artery and left ventricle motion models from preoperative 4D Computed Tomography Angiography (CTA) scans. Through temporally and spatially aligning this model with the intraoperative endoscopic views of the patient's beating heart, this work assists the surgeon to identify and locate the correct coronaries during the TECAB precedures. Thus this work has the prospect of reducing the conversion rate from TECAB to conventional coronary bypass procedures. This thesis mainly focus on designing segmentation and motion tracking methods of the coronary arteries in order to build pre-operative patient-specific motion models. Various vessel centreline extraction and lumen segmentation algorithms are presented, including intensity based approaches, geometric model matching method and morphology-based method. A probabilistic atlas of the coronary arteries is formed from a group of subjects to facilitate the vascular segmentation and registration procedures. Non-rigid registration framework based on a free-form deformation model and multi-level multi-channel large deformation diffeomorphic metric mapping are proposed to track the coronary motion. The methods are applied to 4D CTA images acquired from various groups of patients and quantitatively evaluated

Algorithms and mathematical methods for extraction of functional information from magnetic resonance images of the heart

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