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

描述（由申请人提供）：低伽马核（例如31P， 13C和23Na） MRI/MRSI为研究人体系统的代谢和生理提供了无与伦比的成像方式。不幸的是，由于低伽马核的自然丰度较低，这种有前途的技术存在低信噪比和长采集时间的问题。最近超极化13C方法的突破已经证明了前所未有的~50,000倍的体内信噪比增益，这为MR代谢成像提供了巨大的新机会。然而，它的快速信号衰减（约1分钟）是将这种革命性技术应用于体内应用的挑战。高场并行成像具有固有的高灵敏度和快速采集的优点，将是解决信噪比和采集时间长的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因子的降低、“电缆共振”的增加和不同频率的两个场的干扰，以及单调谐质子收发器阵列的辐射损失和去耦困难等问题，所需要的多通道双调谐收发器阵列的设计困难阻碍了对人体低伽马核的高场平行成像的实现。事实上，收发器阵列的缺乏已经成为低伽马核高场平行MRI/MRSI的主要障碍，并且迫切需要开发强大的设计技术来促进低伽马核检测，特别是超极化13C，使用人体高场平行MR成像。因此，我们提出了一个综合项目，主要基于最近发展的共模和差模（CMDM）方法和微带传输（MTL）技术来开发多通道双调谐收发器阵列。该项目的主要目标是：1)通过提出的阵列项目开发通用设计技术，并在UCSF立即进行体内应用；2)建立理论和数值模型，以了解和模拟多通道双调谐收发器阵列在去耦、双频交互、电磁场、谐振频率和SAR方面的性能；3)通过性能比较验证所提出的收发器阵列技术。安全性评估和真实的患者演示。所提出的双调谐收发器阵列技术具有灵敏度高、频率隔离度高、去耦性强、阵列设计能力强、q系数高、结构简单等优点。该研究将为低伽马核高场并行成像多通道双调谐收发器阵列的设计提供可靠的解决方案，并在多核收发器阵列工程中取得重大技术进步。这些发展将对临床前和人体研究中代谢和生理研究的低伽马核高场平行成像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.