INVESTIGATION OF THERAPY IMPROVEMENT USING REAL-TIME PHOTOACOUSTIC IMAGING GUIDED HIGH INTENSITY FOCUSED ULTRASOUND

There are a lot of risks in cancer treatment by invasive surgery, such as bleeding, wound infection, and long recovery time, etc. Therefore, there is great need for minimally- or non-invasive treatment. High intensity focused ultrasound (HIFU) is a rapidly growing and truly non-invasive technology. It has been widely used in therapeutic applications, such as rapid tissue heating and tissue ablation. With proper imaging guidance, HIFU treatment can be performed totally noninvasively. Currently, ultrasound imaging-guided HIFU has been extensively studied. However, ultrasound imaging guidance is less precise because of the relatively low imaging contrast, sensitivity, and specificity for noninvasive detection. In this study, we employed photoacoustic imaging (PAI) technique, which has been developed a novel promising imaging technique for early cancer detection, to guide HIFU treatment. The goal of this study is to investigate the feasibility of PAI to guide, monitor in real time and enhance the HIFU therapy. In this dissertation, as the first step, the integrated PAI and HIFU system had been shown to have the feasibility to guide HIFU both ex vivo and in vivo. Then, the system was improved and developed to a real-time PAI-guided HIFU system. It is demonstrated that the sensitivity of PA detection for HIFU lesion is very high and the saturation of PA signals can be used as the indicator for tissue coagulation. During the temperature measurement using this system, laser-enhanced HIFU heating was found. Thus, we further investigated the laser enhanced technique in both HIFU heating and pulsed HIFU thrombolysis. In the HIFU therapy, laser light was employed to illuminate the sample concurrently with HIFU radiation. The resulting cavitation was detected with a passive cavitation detector. We demonstrated that concurrent light illumination during HIFU has the potential to significantly enhance HIFU by reducing cavitation threshold

The Political Economy of Health Care Reforms

A leading group of health care economists propose solutions to problems related to Medicare, managed care, health insurance, coverage for the uninsured, and the role of tax policy in health care.https://research.upjohn.org/up_press/1184/thumbnail.jp

Doctor of Philosophy

dissertationIn microsurgical operating room environments, it is often necessary to cut and reattach vessels multiple times during surgery. The current method of vascular anastomosis is hand suturing. This technique is time consuming, difficult, and requires complex instruments. To solve this problem, researchers have explored alternative ways to improve this technique. Typical examples are staples, clips, cuffing rings, adhesives, and laser welding. The potential of these techniques has been hindered due to the lack of biocompatibility, complex procedures for use, and general inefficiency. As a result, few of these devices have been commercialized. One promising alternative is a ring-pin coupling device. This device has been shown to be useful for venous anastomosis, but lacks the versatility necessary for arterial applications. One purpose of this study was to optimize a vascular coupling design that could be used for arteries and veins of various sizes. To achieve this, finite element analysis was used to simulate the vessel-device interaction during anastomosis. Parametric simulations were performed to optimize the number of pins, the wing pivot point, and the pin offset of the design. The interaction of the coupler with various blood vessel sizes was also evaluated. The optimal vascular coupling device has four rotatable wings and one translatable spike in each wing. Prototypes were manufactured using polytetrafluoroethylene (PTFE) and high-density polyethylene (HDPE). A set of installation tools was designed to facilitate the anastomosis process. Proof-of-concept testing with the vascular coupler using plastic tubes and porcine cadaver vessels showed that the coupler could be efficiently attached to blood vessels, did not leak after the anastomosis was performed, had sufficient joint strength, and had little impact on flow in the vessel. A simplified finite element model assisted in the evaluation of the tearing likelihood of human vessels during installation of the coupler. The entire anastomosis process can be completed in three minutes when using the vascular coupler to join porcine cadaver vessels. A metal-free vascular coupling system that can be used for both arteries and veins was designed, fabricated, and tested. A set of corresponding instruments were developed to facilitate the anastomosis process. Evaluation of the anastomosis by Scanning Electron Microscopy (SEM) and Magnetic Resonance Imaging (MRI) demonstrated that the installation process does not cause damage to the vessel intima and the vascular coupling system is not exposed to the vessel lumen. Mechanical testing results showed that vessels reconnected with the vascular coupling system could withstand 12.7±2.2 N tensile force and have superior leak profiles compared to hand sutured vessels. The anastomotic process was successfully demonstrated on both arteries and veins in cadaver and live pigs