Development Of X-Ray Imaging Techniques To Improve Image Quality

Abstract

The use of CT to guide percutaneous renal access has not gained widespread use. This is due in part to difficulties coordinating access to the CT scanner, to difficulties using fluoroscopy to match the CT image, and to concerns about radiation exposure to both the patient and physician. We have developed real-time image guidance techniques using electromagnetic (EM) tracking technology that may address these issues. In the EMPrINT project, we are using EM sensors to track the position and orientation of a biopsy needle during a CT-guided renal puncture. This will allow the alignment of the CT image with the patient's anatomy and will allow visualization of the needle tip beneath the skin, which is not otherwise possible. This may make CT-guided renal puncture faster, easier, and safer because it will provide constant feedback on needle position and trajectory without the need for repeated scans. Our long-term goal is to extend this technology to a needle-driver robot that can navigate to and from the kidney through a fixed entry point while avoiding vital structures.

A number of imaging methods have been developed to help guide minimally invasive access to the kidney and its surrounding structures. Most of these rely on ultrasound or fluoroscopy and provide only limited anatomical detail. Percutaneous access to the kidney is often done under fluoroscopic guidance, but the kidney moves with respiration, making it difficult to access the ideal puncture site. Death and colleagues demonstrated that a puncture of the kidney can be more safely and reliably performed using CT guidance. They used CT scans of a cadaver to show that punctures done under fluoroscopy often miss the kidney altogether. Using CT, they were able to select an optimal puncture site through which the kidney could be safely accessed without damaging adjacent organs.