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31 P、13 C和23 Na）MRI/MRSI在研究人体系统的代谢和生理学方面提供了无与伦比的成像模式。不幸的是，由于低伽马核的低天然丰度，这种有前途的技术遭受低信噪比和长采集时间。超极化13 C方法的最新突破已经证明了体内前所未有的~ 50，000倍SNR增益，这为MR代谢成像提供了巨大的新机会。然而，其快速信号衰减（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，是解决信噪比和采集时间长问题的一种解决方案。然而，除了单调谐质子收发器阵列中的挑战之外，由于不同核通道之间的相互作用、劣化的Q因子、增加的“电缆谐振”和具有不同频率的两个场的干扰，所需的多通道双调谐收发器阵列的设计困难阻碍了对人体中的低伽马核的高场并行成像的实现。例如辐射损耗和去耦困难。事实上，收发器阵列的缺乏已经成为低伽马核高场并行MRI/MRSI的主要障碍，并且迫切需要开发用于设计技术的鲁棒技术，以促进使用人体高场并行MR成像的低伽马核检测，特别是超极化13 C。因此，我们提出了一个全面的项目开发多通道双调谐收发器阵列的基础上，主要是最近开发的共模和差模（CMDM）的方法与微带传输（MTL）技术。该项目的主要目标是：1）通过在UCSF的直接体内应用的拟议阵列项目开发通用设计技术，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的去耦，双频相互作用，电磁场，谐振频率和SAR，以及3）通过性能比较、安全性评估和真实的患者演示来验证所提出的收发器阵列技术。所提出的双调谐收发器阵列技术提供了无与伦比的高灵敏度，改善两个频率之间的隔离，足够的去耦，密集间隔的阵列设计的能力，改善Q因子，和易于施工的优点。本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一个强大的解决方案，并导致多核收发器阵列工程的重大技术进步。这些发展将是至关重要的未来成功的低伽马核高场并行成像的代谢和生理研究在临床前和人体研究。 公共卫生相关性：拟议项目的成功结果将推动低伽马核MRI/MRSI以高灵敏度和速度非侵入性地研究人类健康和疾病状况下的代谢和生理学，并使低伽马核，特别是超极化13 C，MRI/MRSI临床实用。这项研究工作将对更好地理解人类生理学、病理学、代谢和疾病产生直接影响，可能在分子水平上。

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. PUBLIC HEALTH RELEVANCE: The successful outcome of the proposed project will advance the low-gamma nuclear MRI/MRSI with high sensitivity and speed for studying metabolism and physiology in health and diseased conditions in human non- invasively, and make the low-gamma nuclear, in particular, hyperpolarized 13C, MRI/MRSI clinically practical. The research effort will have an immediately impact to better understanding of human physiology, pathology, metabolism and diseases, at molecular level possibly.