Novel Applications of High Temperature Superconducting Coils for MR Imaging

• Main Authors: In-Tsang Lin, 林胤藏
• Other Authors: Jyh-Honrg Chen
• Format: Others
• Language: en_US
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/78599332609223378176

博士 === 國立臺灣大學 === 生醫電子與資訊學研究所 === 99 === Throughout the development in biomedicine, magnetic resonance imaging (MRI) has become an important approach for neuroscience research and clinical applications. Neuroscience research and clinical applications both higher spatial and higher temporal resolutions are expected to help acquire finer details of the imaging object. However, as the imaging resolution goes higher, signal-to-noise ratio (SNR) limits the accuracy of quantitative MR microscopy. Compared with conventional diffusion MRI techniques, high-temperature superconducting (HTS) radio-frequency (RF) coils have been proposed as a promising tool for tissue microscopy with high resolution because of its low-resistance characteristic for MR probe design. However, the potential of HTS RF coils on clinical applications has not been well demonstrated yet. Therefore, the overall objective of this dissertation is threefold and targeted to facilitate the techniques of HTS RF coils for the use of MRI. First, we built the HTS RF surface coils and its applications. Second, we developed a HTS RF volume coil and its applications. Finally, we verified the HTS RF surface coils on the investigations of the clinical research. In Part I, we aim at the study of simulations and measurements of the HTS RF surface coils in a 3T MRI. Our results showed that HTS RF surface coil of a 40 mm in diameter provided an average SNR gain of approximately 3.8 folds on our 3T MRI system. Next, we concentrate on the use of the HTS surface coils in enhancing the diffusion tensor imaging. Results showed that the cooled HTS surface coil with a standard deviation of deviation angles significantly reduced from 44.38° to 18.66°. Furthermore, the fiber tractography of a rat’s corpus callosum (CC) demonstrated the advantage of using a cooled HTS surface coil to investigate the neural connectivity as well and a spontaneous tumor of rat brain is presented with a HTS surface coil. Finally, it was also demonstrated that the SNR using the HTS surface coil of 200 mm in diameter was higher than that of a copper surface coil for the MRI study of a human hand by 1.95 folds. In Part II, we focus on a new Bi-2223 superconducting saddle coil and designed for the magnetic resonance image of a mice’s whole body in a Bruker 3T MRI system. The SNR of a HTS saddle coil at 77 K doubled compared with that of a home-made copper saddle coil for a mice whole body MR study. In Part III, we focused on the studies of edilepticus-induced hippocampal injury in the pilocarpine rat model. These data suggested an enhanced image contrast that may contribute to the early targeted intervention which could minimize brain injury and its associated morbidities. Then, we focused on the three-week observation of vascular endothelial growth factor (VEGF) isoform 189 by using a HTS coil. The results helped elucidate the role of different VEGF isoforms in inducing tumor angiogenesis, the interaction between the structure of tumor angiogenesis, and the mechanisms underlying the association between the expression of a specific VEGF isoform in a tumor and the patient’s clinical outcome in human cancers. In summary, we successfully demonstrated the potential of HTS RF coils on clinical applications. Additionally, we built a HTS volume coil. The use of a HTS volume coil not only improved SNR but also enabled a simple one scan of a mouse’s whole body. Finally, we apply the HTS RF coils with the study of a spontaneous tumor of rat brain, edilepticus-induced hippocampal injury and VEGF 189. And we demonstrated the HTS RF coils be helpful in clinical research. Conclusively, our proposed methods successfully built the HTS RF coil on MRI by increasing SNR, which will be potentially useful to facilitate the neuroscience research and clinical applications.