Browsing by Subject "optoacoustic"
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Item Engineering functionalized gold nanoparticles as a molecular-specific contrast agent to enhance optoacoustic detection of breast cancer cells(2008-12-02) Mohammad Eghtedari; Massoud Motamedi; Vicente Resto; Nicholas A Kotov; Malcolm Brodwick; Gracie VargasMolecular targeting of malignant tumors is a promising field of research that could potentially revolutionize the diagnosis and treatment of many types of cancer including breast. Delivering molecular specific contrast agents to breast cancer cells would enhance the sensitivity and specificity of imaging methods to detect cancer foci at earlier stages, when complete cure is possible. Optoacoustic tomography (OAT) is a non-invasive imaging modality that can be used to produce an image of the distribution of light absorbing components deep within a turbid medium such as human breast. OAT could potentially be used to image breast tumors based on their enhanced angiogenesis; however, its sensitivity and specificity would be limited due to the lack of abnormal angiogenesis at the early stages of tumor growth.\r\nGold nanoparticles generate strong acoustic signal upon pulse laser irradiation and thus are detectable at low concentrations using optoacoustic technique. The goal of this dissertation is to engineer functionalized gold nanoparticles and employ them as a contrast agent for optoacoustic detection of cancer cells.\r\nTo achieve this goal: 1) gold nanoparticles were fabricated in different shape and sizes and their physicochemical properties were optimized for both tumor targeting and optoacoustic detection; 2) the biological properties of fabricated gold nanoparticles were evaluated in vitro and in vivo by determining their stability, toxicity, biodistribution, and molecular targeting properties; 3) the performance of gold nanoparticles to target cancer cells and function as a contrast agent for OAT were assessed in vitro using breast phantoms and then in vivo using animal models.\r\nItem Noninvasive optoacoustic monitoring of blood oxygenation in large blood vessels(2007-09-19) Hans-Peter Franz Brecht; Rinat Esenaliev; Stanislav Emelianov; Massoud motamedi; Harvey Fishman; Gracie vargasContinuous monitoring of cerebral blood oxygenation is critically important for successful treatment of patients with severe traumatic brain injury and patients undergoing cardiac surgery. At present, the techniques for monitoring blood oxygenation are invasive. We propose the noninvasive monitoring of cerebral venous blood hemoglobin saturation (SvO2) by optoacoustic probing of blood circulating in the internal jugular vein (IJV). This thesis describes the tests of the optoacoustic system with three different probes in phantoms, in vitro, and in vivo in sheep along with different data processing algorithms. A LabView®-based scanning system, that automatically moves the optoacoustic probe across the IJV while continuously taking measurements, was developed and used for testing the optoacoustic probes. Automatic signal processing determined the signal with the best probe-vessel alignment which was then used for further processing. The scanning system was tested in phantoms using solutions with different absorption coefficients and with blood at various levels of hemoglobin saturation (SO2). Amplitudes and profiles of the optoacoustic signals recorded from the phantoms closely followed the SO2 changes in accordance with blood optical properties. These data indicate that the scanning system is capable of improving the accuracy of noninvasive monitoring of hemoglobin saturation by minimizing errors associated with lateral misalignment of the probe with respect to blood vessels.