Development of radiological clips having ultrasound identification

点击翻译按钮获取中文摘要

PROJECT SUMMARY Radiological markers or clips are an important tool for diagnostic imaging because they can be placed in the body allowing identification of specific tissues over time and over multiple scans. For neoadjuvant chemotherapy (NAC) in breast cancer, imaging is used to stage tumor size, to identify possible lymph nodes for metastases, to guide biopsy of both tumors, lesions and lymph nodes and to monitor the size and appearance of tumors over time. Between the initial identification of a tumor and positive lymph nodes, chemotherapy application and surgery, several months can pass. Before NAC, tumor, lesions and suspicious lymph nodes are often marked with radiological clips in order to be able to re-identify them before surgery. This is necessary because the appearance of the tumors and lymph nodes can change or even normalize over the course of NAC. In recent years, a multitude of clips have been designed and manufactured with the goal of providing better image contrast and identification under real-time imaging with modalities such as ultrasound. Ultrasound is preferred in these applications because it is safe, real time, portable and can be used at the bedside. Initially it was thought that simple clip designs made from metal would provide sufficiently high contrast for ultrasound that locating the clips in B-mode ultrasound would be straightforward. However, in practice, identification of radiological clips can be difficult as multiple bright scatterers in the imaging field can look in appearance similar to the signal from a clip. As a result, over time new clips have been developed that have a variety of shapes and sizes, different surface textures and compound material properties. While manufacturers have asserted that these clip designs solve the problem of visualization on ultrasound B-mode and {allow identification of different tissues}, these claims have not been realized in practice. The problem of proper visualization is still significant and these clips are not always identifiable especially on follow on imaging studies after initial clip placement. Therefore, we propose to develop a new type of radiological clip that can provide the ability to be visualized by ultrasonic imaging but also to identify the specific clip in the tissue. The new clip consists of a small biocompatible ultrasonic source and driving circuit that detects an ultrasonic imaging pulse. The ultrasonic imaging pulse then triggers the circuit, comprised of several small oscillators, to drive the ultrasonic source to emit a specific encoded ultrasonic signal. The ultrasonic signal will provide a unique identification code allowing the clip to not only be clearly visualized and localized with specificity by ultrasound, but also to identify the specific clip, i.e., ultrasound identification (USID). {Our clip visibility does not depend on the echogenicity of the clip but on the unique clip signal that is emitted and processed}. To develop these radiological clips we propose two specific aims. The first aim is to design, build and test USID radiological clips capable of providing unique ID tags. The second aim is to demonstrate the capabilities of a stand-alone version of the radiological clips in tissue- mimicking phantoms and {in vivo}.