Multichannel Dual-tuned Transceiver Techniques for Human Low-Gamma Nuclei MR

描述(申请人提供)：低伽马核(如31P、13C和23Na)MRI/MRSI在研究人体系统的新陈代谢和生理学方面提供了无与伦比的成像手段。遗憾的是，由于低伽马核的自然丰度较低，这项有前途的技术存在信噪比低和捕获时间长的问题。最近在超极化~(13)C方法方面的突破表明，体内信噪比有了前所未有的~50,000倍的提高，这为磁共振代谢成像提供了一个新的机会。然而，其快速的信号衰减(~1分钟)对于将这项革命性的技术应用于体内应用是一个挑战。高场并行成像具有固有的高灵敏度和快速捕获的优点，是缓解信噪比和长捕获时间问题的一种解决方案。然而，由于不同核通道之间的相互作用、Q因子的退化、电缆共振的增加以及不同频率的两个场的干扰，以及单调谐质子收发阵列的辐射损耗和解耦困难等挑战，所需的多通道双调谐收发信机阵列的设计困难阻碍了对人类低伽马核高场并行成像的实现。事实上，收发信机阵列的缺乏已经成为低伽马核高场并行MRI/MRSI的主要障碍，迫切需要开发稳健的技术来设计技术，以促进利用人类高场并行磁共振成像进行低伽马核探测，特别是超极化13C核探测。因此，我们提出了一个基于最近发展的微带传输(MTL)技术的共模和差模(CMDM)方法的多通道双调谐收发信机阵列的综合方案。该项目的主要目标是：1)通过建议的阵列项目开发通用设计技术，并立即在加州大学旧金山分校进行体内应用；2)建立理论和数值模型，以了解和模拟多通道双调收发机阵列在去耦合、双频相互作用、电磁场、谐振频率和合成孔径雷达方面的情况；以及3)通过性能比较、安全评估和真实患者演示来验证所提出的收发机阵列技术。所提出的双调谐收发信机阵列技术具有灵敏度高、改善两个频率之间的隔离度、充分解耦、密集间隔阵列设计能力、改善的Q因子和易于构造等无可比拟的优点。这项研究将为低伽马核高场并行成像多通道双调谐发信机阵列的设计提供可靠的解决方案，并在多核收发信机阵列工程中取得重大技术进步。这些进展将对低伽马核高场并行成像在临床前和人体研究中用于代谢和生理研究的未来成功至关重要。

DESCRIPTION (provided by applicant): Low gamma nuclei (e.g. 31P, 13C & 23Na) MRI/MRSI offers an unmatched imaging modality in studying metabolism and physiology of the human system. Unfortunately, due to the low natural abundance of low gamma nuclei, this promising technique suffers from the low SNR and long acquisition time. Recent breakthroughs in hyperpolarized 13C methods have demonstrated an unprecedented ~50,000-fold SNR gain in-vivo, which provides a great new opportunity for MR metabolic imaging. However its fast signal decay (~1 minute) is a challenge for applying this revolutionary technique to in-vivo applications. With the proven advantages of the intrinsically high sensitivity and fast acquisition, high-field parallel imaging would be a solution to alleviate SNR and long acquisition-time problems. However, implementation of the high-field parallel imaging to low-gamma nuclei in human is hindered by design difficulties for the required multichannel double- tuned transceiver arrays due to the interaction between the different nuclei channels, degraded Q factors, increased "cable-resonance" and interference of two fields with different frequencies, besides the challenges in a single-tuned proton transceiver array, such as the radiation losses and decoupling difficulties. In fact, the lack of the transceiver arrays has become a major hindrance for low-gamma nuclear high-field parallel MRI/MRSI, and there is a pressing demand for developing robust techniques for design techniques to facilitate the low- gamma nuclei detection, especially for hyperpolarized 13C, using high-field parallel MR imaging in human. Therefore, we propose a comprehensive project for developing multichannel double-tuned transceiver arrays based mainly on the recently developed common-mode and differential mode (CMDM) method with the microstrip transmission (MTL) technique. The major goals of this project are focused on 1) development of general design techniques through proposed array projects with immediate in-vivo applications at UCSF, 2) establishment of theoretical and numerical models to understand and simulate the multichannel double-tuned transceiver arrays in decoupling, dual-frequency interaction, EM fields, resonant frequencies, and SAR, and 3) validations of proposed transceiver array technology with performance comparison, safety assessment and real patient demonstration. The proposed double-tuned transceiver array techniques provides unmatched advantages of high sensitivity, improved isolation between two frequencies, sufficient decoupling, capability of dense-spaced array design, improved Q-factors, and easy construction. This research will provide a robust solution to design of multichannel double-tuned transceiver array for low-gamma nuclear high-field parallel imaging and result in significant technological advances in multinuclear transceiver array engineering. These developments will be critical to the future success of low-gamma nuclear high-field parallel imaging for metabolic and physiological investigations in preclinical and human studies.