Browsing by Subject "Image"

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    Experimental Measurement of Blood Pressure in 3-D Printed Human Vessels
    (2022-05) Talamantes, John, Jr.; Yu, Huidan (Whitney); Chen, Jie; Zhu, Likun
    A pulsatile flow loop can be suitable for measurement of in vitro blood pressure. The pressure data collected from such a system can be used for evaluating stenosis in human arteries, a condition in which the arterial lumen size is reduced. The objective of this work is to develop an experimental system to simulate blood flow in the human arterial system. This system will measure the in vitro hemodynamics using 3-D prints of vessels extracted from patient CT images. Images are segmented and processed to produce 3-D prints of vessel geometry, which are mounted in the loop. Control of flow and pressure is made possible by the use of components such as a pulsatile heart pump, resistance, and compliance elements. Output data is evaluated by comparison with CFD and invasive measurement. The system is capable of measurement of the pressures such as proximal, Pa, and distal, Pd, pressures to evaluate in vivo conditions and to assess the severity of stenosis. This is determined by use of parameters such as fractional flow reserve (FFR=Pd/Pa) or trans-stenotic pressure gradient (TSPG=Pa-Pd). This can be done on a non-invasive, patient specific basis, to avoid the risk and high cost of invasive measurement. In its operation, the preliminary measurement of blood pressures demonstrates agreement with the invasive measurement as well as the CFD results. These preliminary results are encouraging and can be improved upon by continuing development of the experimental system. A working pulsatile loop has been reached, an initial step taken for continued development. This loop is capable of measuring the flow and pressure from in a 3-D printed artery. Future works will include more life-like material for the artery prints, as well as cadaver vessels.
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    "Social Selves"
    (2016) Hill, Chris; Petranek, Stefan
    In speaking of work from his photo book "American Surfaces," Stephen Shore says "...all of it was looking at the culure, the build culture." The surface of things at times expands beyong two dimensional flateness and visual aesthetic to agents involved in creating and consuming such surfaces. This expansion of two dimensional flateness to three dimensional dynamics is especially evident in cities alive with varying degerees of personhood imposed and projected upon surfaces. Image content and how images function are among questions I address in my photographic practice while taking into account theories of Martin Heidegger, W.E.B. Du Bois, Karl Marx and advertising strategies. Applying said theory to my photographic practice along with the application of paint to photographs has led to a creation of images that expands from two dimensional flatness to three dimensions in terms of form and content.
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    Topographic staging of tau positron emission tomography images
    (Elsevier, 2018-02-14) Schwarz, Adam J.; Shcherbinin, Sergey; Slieker, Lawrence J.; Risacher, Shannon L.; Charil, Arnaud; Irizarry, Michael C.; Fleisher, Adam S.; Southekal, Sudeepti; Joshi, Abhinay D.; Devous, Michael D., Sr.; Miller, Bradley B.; Saykin, Andrew J.; Alzheimer's Disease Neuroimaging Initiative; Radiology and Imaging Sciences, School of Medicine
    Introduction: It has been proposed that the signal distribution on tau positron emission tomography (PET) images could be used to define pathologic stages similar to those seen in neuropathology. Methods: Three topographic staging schemes for tau PET, two sampling the temporal and occipital subregions only and one sampling cortical gray matter across the major brain lobes, were evaluated on flortaucipir F 18 PET images in a test-retest scenario and from Alzheimer's Disease Neuroimaging Initiative 2. Results: All three schemes estimated stages that were significantly associated with amyloid status and when dichotomized to tau positive or negative were 90% to 94% concordant in the populations identified. However, the schemes with fewer regions and simpler decision rules yielded more robust performance in terms of fewer unclassified scans and increased test-retest reproducibility of assigned stage. Discussion: Tau PET staging schemes could be useful tools to concisely index the regional involvement of tau pathology in living subjects. Simpler schemes may be more robust.