Browsing by Author "Sutherland, Garnette"

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    Characterization and Modeling of Brain Tissues Using Fractional Calculus
    (2018-02) Jiao, Shanlin; Sun, Qiao; Sutherland, Garnette; Goldsmith, Peter; Leung, Henry; Pieper, Jeff K.
    Modeling of brain tissues is essential to better patient outcome. This research aims at modeling brain tissues based on their electrical impedance and viscoelasticity. Fractional order models can accurately model the two properties with few parameters in a wide spectral range. The Cole parameters extracted from step current response was applied to characterize the grey and white matter. Experimental results show that the Cole model fits well to experimental data and proposed Cole parameter extraction method is more effective in identifying Cole parameters. A fractional order viscoelastic model is employed to model the viscoelasticity of brain tissue. The predicted results are compared with the known experimental data and also that of integer order models, indicating the fractional order viscoelastic model can adequately fit all the experimental data with only two parameters.
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    A Multi-Purpose Continuum Robot for Minimally Invasive Surgery
    (2023-01-25) Esfandiari, Mojtaba; Sutherland, Garnette; Tavakoli, Mahdi; Westwick, David; Goldsmith, Peter
    This thesis is about ''A Multi-Purpose Continuum Robot for Minimally Invasive surgery'' which consists of five chapters. It starts with an Introduction and Literature Review that studies some of the most famous surgical robotic systems and analyses their pros and cons. Chapter two has to do with the problem statement and challenges that need to be addressed while designing our specific surgical tool, and a CAD design of a flexible continuum robot will be done for our brain surgery application. In chapter three, the kinematic modeling of the proposed robot is analyzed by a new model based on the Euler spirals and the results are compared with conventional constant curvature models. In chapter four, a model predictive control algorithm is proposed that considers the input saturation constraints on robot actuators. Finally, a discussion and conclusion will be provided in chapter five.
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    The Interrogation of Traumatic Brain Injury with MR Spectroscopy and Molecular Imaging
    (2016) Lama, Sanju; Sutherland, Garnette; Tomanek, Boguslaw; Colicos, Michael; Zygun, David; Gallagher, Clare
    Metabolic perturbations in early acute severe traumatic brain injury (TBI) using magnetic resonance (MR) spectroscopy, and the prospects of molecular imaging of repetitive mild TBI, form the driving principles of this thesis work. Brain metabolism is thought to be maintained by neuronal-glial metabolic coupling, whereby glia take up glutamate from the synaptic cleft for conversion into glutamine, triggering glial glycolysis and lactate production. This lactate is shuttled into neurons and further metabolized. Using a weight drop model of severe TBI and MR spectroscopy with infusion of 13C labeled glucose, lactate and acetate, this portion of the thesis investigated the hypothesis that neuronal-glial metabolism is uncoupled following severe TBI. High resolution MR spectroscopy revealed significant labeling of lactate irrespective of the infused substrate and decreased labelling of other metabolites. Histopathology, while showing features of severe brain injury, also stained positive for tau. A microtubule associated protein, tau has been shown to accumulate in brains following TBI, particularly those related to sports and combat. It was further hypothesized that tau could be visualized through the administration of a unique anti-tau single domain antibody (sdAb)-nanoparticle complex. Through llama immunization, tau specific sdAbs were isolated, panned and characterized for bioconjugation to MR sensitive NaDyF4-NaGdF4 nanoparticles, towards non-invasive imaging of tau in vivo. At a ratio of ~4 sdAbs per nanoparticle, the complex was able to cross the neuronal membrane and bind to intracellular tau in live hippocampal neuronal cultures. Preliminary in vivo studies, establishing the model for repetitive mild TBI showed considerable tau staining within the entorhinal cortex, dentate gyrus and hippocampal CA3 sector sparing CA1. While there were some T1 changes in MR imaging, clinical translation will require further tests for sdAb – nanoparticle affinity to both tau and hyperphosphorylated tau, optimal dosage and safety, toxicology and clearance profile. It may be concluded that the early increase in brain lactate or lactate storm marks severe TBI; and tau abnormality and associated disrupted axonal transport, may be the hallmark of repetitive mild TBI, making it a potential MR visible biomarker for TBI. These concepts may guide future diagnostic and therapeutic directions.