Development of Superconducting Transcranial Magnetic Stimulation (TMS)

描述（由申请人提供）：我们建议测试开发一种新型经颅磁刺激（TMS）仪器的可行性，该仪器利用超导磁体线圈而不是室温线圈。这种超导TMS装置（sTMS.）利用了由钛-铜制成的II型超导导线可以承载的高电流密度。与常规室温铜基TMS磁体的约1A/mm 2相比，这种导线可以承载具有大约1 kA/mm 2横截面积的密度的电流。由于TMS线圈产生的磁场B取决于导线中的电流、导线的横截面积和匝数，因此可以使用相对小的TMS线圈来最终构建高密度多通道或甚至全头部sTMS。TMS电路的超导段不会产生热量。因此，不需要像室温TMS那样需要特殊的散热器，这使我们能够构建高密度sTMS。在我们的初步测试中，我们能够构建具有2.2 cm直径线圈的TMS系统，其可以产生18，000特斯拉/秒（T/s）的磁场斜坡（dB/dt），这与具有8-12 cm刺激器尺寸的传统TMS系统的20-40 kT/s相当。将在该第一阶段项目中构建的原理验证装置将采用可在约1000 V下工作的电容器，而在初步测试中为100 V。这将使我们能够使用直径为2.0 cm的TMS线圈构建能够提供~40 kT/s的dB/dt的sTMS设备，该线圈具有~4匝，具有1-2 5 H的优化电感。我们将在sTMS线圈正下方的盐溶液浴中测量电场E，以验证该sTMS能够在2-3 cm的距离处产生约100 mV/mm的电梯度，该距离与人脑新皮层的距离相当。一旦我们确定了构建单通道sTMS的可行性，我们建议在第二阶段构建37通道sTMS，以证明可以构建通道间距约为3 cm的高密度sTMS。与传统的TMS设备相比，这种多通道系统有望提供许多显著的优点。四个对角sTMS线圈可以组合以产生形状像线段的聚焦涡流。该电流线的方向可以通过改变施加到四个sTMS线圈的电流来连续调整，以便刺激具有特定方向的目标神经元。通过改变施加到所有通道的电流，可以沿着大脑表面连续地调节涡电流线的位置。今天，TMS是唯一能够刺激大脑焦点区域的技术，不仅可以研究大脑回路的基本功能，还可以作为抑郁症和其他神经/精神疾病的有用治疗方式。基于所提出的设计的TMS设备可以显著增加TMS设备在其他领域的有用性，包括促进中风和其他疾病患者的损伤后重组。公共卫生相关性：在第二阶段开发的多通道超导TMS（sTMS）和可能在商业化阶段（第三阶段）开发的全头部sTMS系统将在TMS非侵入性刺激人脑的应用方面取得重大进展。这将提高TMS治疗各种神经和精神疾病患者的有效性，包括一般的抑郁症和情绪障碍，以及需要康复的中风和创伤性脑损伤。

DESCRIPTION (provided by applicant): We propose to test the feasibility of developing a novel instrument for transcranial magnetic stimulation (TMS) utilizing superconducting magnet coils instead of room-temperature coils. This superconducting TMS device (sTMS.) takes advantage of high current density that can be carried by type II superconducting wires made of niobium-titanium-copper. Such a wire can carry currents with a density on the order of 1 kA/mm2 of cross- sectional area compared to about 1 A/mm2 for conventional room-temperature copper-based TMS magnets. Since the magnetic field B generated by a TMS coil depends on the current in the wire, cross sectional area and number of turns of wire, it is possible to use relatively small TMS coils for eventually constructing a high- density multi-channel or even whole-head sTMS. No heat will be generated by the superconducting segment of the TMS circuit. Thus there is no need for a special heat sink as it is necessary for room-temperature TMSs, allowing us to construct a high-density sTMS. In our preliminary test we were able to construct a TMS system with a 2.2 cm diameter coil that could produce a magnetic field ramp (dB/dt) of 18,000 tesla/sec (T/s), which is comparable to 20-40 kT/s for conventional TMS systems having stimulator dimensions of 8-12 cm. The proof- of-principle device to be constructed in this Phase I project will employ capacitors that can operate at ~1000 V compared to 100V in the preliminary test. This will allow us to construct an sTMS device capable of delivering dB/dt of ~40 kT/s using a 2.0 cm diameter TMS coil with ~4 turns having an optimized inductance of 1-2 5H. We will measure the electrical field E in a bath of saline solution just below the sTMS coil to verify that this sTMS is capable of generating an electrical gradient of ~100 mV/mm at a distance of 2-3 cm comparable to the distance of the neocortex of a human brain. Once we establish the feasibility of constructing a single-channel sTMS, we propose to construct a 37-channel sTMS in Phase II to demonstrate that a high-density sTMS with a channel spacing of ~3 cm can be constructed. Compared to conventional TMS devices, this multichannel system is expected to provide many significant advantages. Four diagonal sTMS coils can be combined to produce a focal eddy current shaped like a line segment. The orientation of this current line can be adjusted continuously by varying the currents applied to the four sTMS coils in order to stimulate target neurons with a specific orientation. The position of the eddy current line can be adjusted continuously along the surface of the brain by varying the currents applied to all the channels. Today, TMS is the only technique capable of stimulating focal regions of the brain to study not only basic functions of the brain circuit, but also to serve as a useful treatment modality for depression and other neurological/psychiatric disorders. TMS devices based on the proposed design could significantly increase the usefulness of TMS devices in other areas including facilitation of post-injury reorganization in patients with stroke and other disorders. PUBLIC HEALTH RELEVANCE: The multichannel superconducting TMS (sTMS) to be developed during Phase II and a whole-head sTMS systems to be developed possibly during the commercialization stage (Phase III) would provide significant advances in applications of TMS to stimulate the human brain noninvasively. This will increase the effectiveness of TMS in treating patients with various neurological and psychiatric disorders including depression and mood disorder in general, and stroke and traumatic brain injury that require rehabilitation.