Browsing by Subject "Ultrasonic imaging"
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Item Integrated system for ultrasonic, elasticity and photoacoustic imaging(2008-08) Park, Suhyun, 1977-; Emelianov, Stanislav Y.By integrating three complementary imaging techniques - ultrasound, elasticity and photoacoustic imaging, a hybrid imaging system utilizing an array transducer is proposed for various biomedical imaging applications including cancer detection, diagnosis and therapy monitoring. Simultaneous imaging of the anatomy (ultrasound imaging), changes in biomechanical properties (elasticity imaging) and cancer-induced angiogenesis (photoacoustic imaging) of tissue is based on many synergistic features of these modalities and may result in a unique and important imaging tool. In this study, numerical analysis and experimental studies are presented to demonstrate the feasibility, to evaluate the performance, and also to improve the quality of the combined array-based ultrasound, elasticity and photoacoustic imaging system. To estimate spatial resolution, a point source was imaged using ultrasound and photoacoustic imaging modes. Then, several tissue mimicking phantoms were examined using ultrasound, photoacoustic and elasticity imaging. In elasticity imaging, ultrasound frames were acquired during deformation of the tissue. To reduce the data acquisition time of the system, high frame rate imaging was used. High frame rate imaging is possible by transmitting a broader and less focused ultrasound beam but the image quality is sacrificed. Thus, we compared the quality of the high frame rate and conventional ultrasound images. In photoacoustic imaging, acoustic transients are generated simultaneously in the entire volume of the laser irradiated tissue. Hence, image formation (beamforming) algorithms were developed based on the characteristics of the photoacoustic signals. Then, adaptive beamforming method is suggested to improve the image quality of the photoacoustic imaging. The results of the numerical analyses and experimental studies clearly indicate that ultrasound, elasticity and photoacoustic imaging techniques complement each other and together provide critical information needed for the reliable detection and diagnosis of diseases.Item Magneto-motive detection of nanoparticles and hemoglobin(2006) Oh, Jung Hwan; Milner, Thomas E.Magneto-motive diagnostic systems combining optical coherence tomography (OCT) and ultrasonography (US) can be used to detect magnetic nanoparticles and red blood cells (RBCs) containing iron in response to an external magnetic field. Magnetic force on magnetic nanoparticles and hemoglobin iron may be varied by applying an external current to a solenoid containing a conical iron core that substantially increases and focuses a magnetic field (Bmax = 2 Tesla). In studies using superparamagnetic iron oxide (SPIO) and monocrystalline iron oxide (MION) nanoparticles, the hypothesis of this research is that tissue-based macrophage cells can be detected in an external magnetic field after taking up SPIO nanoparticles in liver and MION nanoparticles in the atherosclerotic high-risk plaque. Therefore, magneto-motive OCT (MM-OCT) and magneto-motive ultrasound (MM-US) can detect iron-laden tissue motion in response to an external magnetic field. Important parameters of magnetic force-induced displacement are optical path length change (Δp) in MM-OCT and Doppler frequency shift (fd) in MM-US. Variations of these parameters in response to an external magnetic field may aid understanding and identification of lesions in biomedical engineering applications, especially inflammatory diseases such as cancer and atherosclerosis. In studies involving human red blood cells (RBCs), the hypothesis of the proposed research is that magnetic permeability of deoxygenated RBCs is sufficient such that when positioned in a high magnetic field gradient, translational and rotational motion is modified. Moreover, our hypothesis states that a high magnetic field can increase blood viscosity, resulting in reduction of blood flow rate, enabling not only imaging and measurement of small caliber vessels, but also providing improved laser treatment for port wine stains (PWS), telangiectasias, and hemangiomas.