An Integrated Microfluidic Cryo-Cooling System for MR Microcoils

描述（由申请人提供）：将开发一种低温微流体冷却系统，该系统可以将MRI表面线圈冷却至液氮温度，而不影响成像表面的温度，同时保持线圈和目标样本之间的最小距离以获得最大灵敏度。用于提高线圈灵敏度的常规低温恒温器需要线圈和样品之间的厚绝缘层，并且不适用于通常具有相对浅的穿透深度的表面线圈。因此，可以保持表面线圈和样品紧密接近以获得最大线圈灵敏度的低温冷却系统可以防止与厚低温恒温器相关联的SNR损失，并且因此提供比未冷却线圈显著更高的SNR。微加工技术将用于开发具有集成表面线圈的微流体低温冷却系统，以用微量（纳升）液氮冷却线圈。在表面线圈和成像表面的开发系统的温度分布将进行评估，然后通过表征导体长度和几何形状的参数空间。将系统并行化到表面线圈阵列的能力也将被表征。将使用MRI对系统进行评价和优化，并将低温冷却表面线圈与非冷却表面线圈进行比较。如果成功的话，这将使平面表面微线圈的低温冷却用于高分辨率生物样品成像，而不需要厚的常规低温恒温器。预期所得到的系统在信噪比（SNR）上具有超过5倍的改善，具有将扫描时间减少25倍而不损失图像质量的潜力。所提出的研究的意义在于，所得到的系统可以为当前的成像需求提供关键工具，例如通过使用高密度表面线圈阵列或超快成像来对小目标（例如单细胞）进行成像，以监测生物样品（例如血管或脑切片）中的实时生理变化。所开发的微流体低温冷却技术不限于特定的表面线圈配置，而是可以广泛地应用于各种其他平面和非平面微线圈配置。这项工作可以进一步扩展到使用液氮冷却高温超导（HTS）表面线圈阵列，以进一步提高扫描时间，而不影响要成像的生物样品。本计画旨在发展一种整合磁振表面线圈之微流控低温冷却系统，以进行生物样本之高解析度磁振成像。

DESCRIPTION (provided by applicant): A cryogenic microfluidic cooling system that can cool MRI surface coils to liquid nitrogen temperature without affecting the temperature at the imaging surface, while maintaining minimal distance between the coils and the target samples for maximum sensitivity will be developed. Conventional cryostats used to improve coil sensitivity require a thick insulating layer between the coil and the sample and are not applicable to surface coils that typically have relatively shallow penetration depth. Therefore, a cryogenic cooling system that can keep the surface coil and the sample in close proximity for maximum coil sensitivity can prevent the SNR loss associated with thick cryostats and therefore provide significantly higher SNR than un-cooled coils. Microfabrication technology will be used to develop a microfluidic cryo-cooling system with integrated surface coils to cool the coil with minute (nanoliter) amount of liquid nitrogen. Temperature profiles at the surface coil and the imaging surface of the developed system will be evaluated followed by characterizing the parameter space of conductor length and geometry. The ability to parallelize the system to surface coil arrays will be also characterized. The system will be evaluated and optimized using MRI and the cryo-cooled surface coils will be compared to un-cooled surface coils. If successful, this will enable cryo-cooling of planar surface microcoils for high-resolution biological sample imaging without the need for a thick conventional cryostat. The resulting system is expected to have an improvement of a factor over 5 in signal-to-noise ratio (SNR) with a potential to reduce scan time by a factor of 25 with no loss in image quality. The significance of the proposed research is that the resulting system can provide critical tools for the current imaging needs, such as imaging small targets (e.g. single cells) by using high-density surface coil arrays or ultra-fast imaging for monitoring real-time physiological changes in biological samples such as blood vessels or brain slices. The developed microfluidic cryo-cooling technology is not limited to a specific surface coil configuration but can be applied broadly to various other planar and non-planar microcoil configurations. This work can be expanded further to cool high temperature superconducting (HTS) surface coil arrays using liquid nitrogen to further improve scanning time without affecting the biological samples to be imaged. This project seeks to develop a microfluidic cryo-cooling system integrated with MR surface coils for high- resolution MR imaging of biological samples.