Conductors, joints, and Coils for Cryogen Free Whole Body 3 T MRI systems

描述（由申请人提供）：目前安装的大多数全身MRI系统是基于1.5 T液体he冷却的NbTi磁体，但3.0 T系统的安装速度正在迅速增加。然而，氦气成本的增加是有据可证的，这导致MRI系统生命周期成本的增加，这可能限制传统患者群体的可用性，并限制将可用性扩展到传统上服务较差的患者群体的能力。这个问题的根本原因是世界范围内氦气的日益短缺。主要的MRI磁体制造商（西门子、通用电气和菲利普斯）都有开发项目，重点是将1.5T螺螺管线圈从液氦浴冷却转换为干式（无制冷机）传导冷却。事实上，不需要液氦冷却（即无冷剂，传导冷却，操作）正变得越来越重要。目前，磁共振成像系统（2000-3000升）在出厂前都是用液态氦填充的，在美国的成本约为20-30万美元。鉴于从2006年到2011年，LHe的成本增加了两倍，并且预计将继续增加，因此可以预期液体- he MRI单元的成本会相应增加。在世界上的一些地方，液体He的价格约为每升9-13美元，而在其他地方，每升约为25 - 70美元，根据MRI的大小和位置，重新填充的成本为1.8万至21万美元。因此，预计对不依赖液体He冷却的MRI磁体的需求将不断增长。甚至除了核磁共振的液冷剂问题之外，冷冻核磁共振磁体的发展也可以允许新的几何形状和核磁共振应用，开辟新的治疗可能性。然而，我们必须关注行业可以将这项新技术商业化的地方。因此，拟议的计划侧重于开发技术，使使用冷冻模式的无冷冻剂3t系统成为可能。我们建议通过；(1)在适合3t MRI （4-10 K, 0-4 T）的磁场和温度范围内，将目前开发的1g导线的实际MgB2工程电流密度（Je）提高一个数量级；(2)在(1)的多丝2g导线中开发足以用于持久模式磁铁操作的n值（在相关磁场范围内为30或更多）；(3)开发具有足够细节的磁铁模型，以开发导体规格/目标，以及在冷却、(4)确定通道内导线MgB2/Cu的适当Cu/SC比，并演示其长长度制造；(5)使用项目(4)的WIC演示整个线圈的一个部分，具有所需的电流，n值，温度梯度和淬火性能；(6)在磁铁工程友好的反应和风模式下为MgB2导体开发坚固的持久接头。

DESCRIPTION (provided by applicant): Most presently installed full-body MRI systems are based on 1.5 T liquid-He- cooled NbTi magnets, but the rate of installation of 3.0 T systems is rapidly increasing. However, the increasing cost of helium is well documented, and this leads to increases in the life cycle cost of MRI systems, which could limit ready access for traditional patient groups, and limit the ability to expand availability to traditionally less well served patint groups. The root cause of the problem is the growing shortage of helium worldwide. The major MRI magnet manufacturers (Siemens, GE, and Phillips) each have development programs focused on converting the 1.5T solenoid coils from liquid helium bath cooling to dry (cryogen free) conduction cooling. Indeed, freedom from the need for liquid-helium cooling (i.e. cryogen free, conduction-cooled, operation) is becoming more and more important. Presently, MRI systems (2000-3000 liters) are filled with liquid He helium at the factory prior to shipping at a cost in the U.S. of about 20-30 K. Given that from 2006 to 2011 the cost of LHe has tripled, and it is expected to continue to increase, corresponding increases in the cost of liquid-He MRI units can be expected. In some parts of the world liquid He costs about $9-13 per liter and in others about $25 to $70 per liter leading to re-filling costs of $18,000-$210,000 depending on the MRI's size and location. Thus a growing demand is predicted for MRI magnets that do not depend on liquid He for cooling. Even beyond the liquid cryogen issues for MRI, the development of cryocooled MRI magnets could allow for new geometries and MRI applications, opening up new treatment possibilities. However, we must focus where the industry can transition this new technology commercially. Accordingly, the proposed program focuses on developing the technology to enable cryogen free 3 T systems using a cryocooled mode. We proposed to do this by; (1) Increases practical MgB2 engineering current density, Je, by one order of magnitude over presently developed 1 G wire, in the fields and temperature ranges appropriate to 3 T MRI (4-10 K, 0-4 T), (2) Developing n-values sufficient for persistent mode magnet operation (30 or more in the relevant field range) in the multifilament 2 G wires of (1), (3) Developing a magnet model with sufficient detail to develop the conductor specification/targets, and the tradeoffs between cooling, temperature gradients across a coil segment, and conductor performance, (4) Determining the proper Cu/SC ratio for wire-in-channel MgB2/Cu, and demonstrate its long-length manufacture, (5) Demonstrating one segment of the total coil, using the WIC of item (4), with the needed current, n-value, temperature gradient, and quench performance, and (6) Developing a robust persistent joint for MgB2 conductors in a magnet engineering friendly react & wind mode.