Integrated RF/shim body coil array for MRI with localized shimming

项目摘要/摘要 空气/组织界面磁化率差异引起强局域静磁场(B0) 不均匀，不能用全身球谐(SH)垫片有效地进行垫片 线圈安装在临床MRI扫描仪上，导致图像失真、模糊、信号丢失和 脂肪抑制不完全。这些伪像在临床应用中引入了诊断的不准确性，并且 在身体成像方面尤其严重，它比大脑遭受更广泛的B0不均匀 成像，以及基于快速成像序列的技术，例如所使用的回波平面成像 在许多临床应用中，如弥散加权成像(DWI)。因此，Body DWI是最多的 具有挑战性的应用程序和能够实现高B0同质性的新技术的开发 为了提高其空间保真度和准确性，并增加其临床应用价值，迫切需要在人体内使用。 最近提出了一个新的概念，称为集成并行接收、激励和垫片(iPRES 建议，允许射频(RF)电流和直流(DC)电流在同一线圈中流动， 从而利用单个集成RF/垫片线圈阵列实现RF接收和局部B0垫片。这 因此，新技术可以在不降低信噪比的情况下有效地填补局部的B0不均匀 比率(SNR)或需要磁铁钻孔中的额外空间，这在人脑中得到了证实 采用32通道iPRES磁头线圈阵列。然而，它在人体成像方面的应用更具挑战性， 这是因为体线圈阵列中的线圈元件较大，以及更广泛的B0不均匀。 该建议的目标是开发下一代iPRES线圈设计，称为自适应iPRES(N)， 以实现身体的高度B0同质性。具体地，32通道主体线圈的每个RF线圈元件 阵列将划分为N个较小的独立DC环路，并将添加交换机来分配DC 根据需要将电流输入适当的直流回路，从而实现更高的灵活性和空间分辨率 用于本地化的B0垫片，不需要额外的电源。将首先执行模拟以 优化线圈设计(目标1)。然后将通过使用一种新的开关技术来实现线圈阵列 并将集成到3T磁共振扫描仪(AIM 2)中。最后，将通过进行台架测试进行验证， 体模实验和人体实验，包括高分辨率腹部DWI(目标3)。 这项新技术将在人体内提供前所未有的B0同质性，而不会影响SNR，这 将显著提高空间保真度、图像质量、诊断准确性、扫描效率和患者 广泛的临床应用中的舒适性，包括身体DWI。它还将在宽范围内实现垫片 钻孔和PET/MR扫描仪，它们没有SH垫片线圈，将在 未来的扫描仪，导致更低的制造成本和更宽的磁铁孔径，以适应更大的患者。

Project Summary / Abstract Magnetic susceptibility differences at air/tissue interfaces induce strong localized static magnetic field (B0) inhomogeneities, which cannot be effectively shimmed with the whole-body spherical harmonic (SH) shim coils onboard clinical MRI scanners, resulting in image artifacts such as distortions, blurring, signal loss, and incomplete fat suppression. These artifacts introduce diagnostic inaccuracies in clinical applications and are particularly severe in body imaging, which suffers from more extensive B0 inhomogeneities than brain imaging, and for techniques based on fast imaging sequences such as echo-planar imaging, which is used in many clinical applications such as diffusion-weighted imaging (DWI). Thus, body DWI is one of the most challenging applications and the development of a new technology that can achieve a high B0 homogeneity in the body is critically needed to improve its spatial fidelity and accuracy and to increase its clinical utility. A novel concept, termed integrated parallel reception, excitation, and shimming (iPRES), was recently proposed, which allows a radiofrequency (RF) current and a direct current (DC) to flow in the same coil, thereby enabling RF reception and localized B0 shimming with a single integrated RF/shim coil array. This new technology can thus effectively shim localized B0 inhomogeneities without reducing the signal-to-noise ratio (SNR) or requiring additional space in the magnet bore, which was demonstrated in the human brain with a 32-channel iPRES head coil array. However, its application to body imaging is more challenging, because of the larger coil elements in body coil arrays and the more extensive B0 inhomogeneities. The goal of this proposal is to develop the next generation of iPRES coil design, termed adaptive iPRES(N), to achieve a high B0 homogeneity in the body. Specifically, each RF coil element of a 32-channel body coil array will be divided into N smaller independent DC loops and switches will be added to distribute the DC currents into the appropriate DC loops as needed, resulting in a much higher flexibility and spatial resolution for localized B0 shimming, without requiring additional power supplies. Simulations will first be performed to optimize the coil design (Aim 1). The coil array will then be implemented by using a novel switch technology and will be integrated into a 3T MRI scanner (Aim 2). Finally, it will be validated by performing bench tests, phantom experiments, and human experiments, including high-resolution abdominal DWI (Aim 3). This new technology will provide an unprecedented B0 homogeneity in the body with no SNR penalty, which will substantially improve the spatial fidelity, image quality, diagnostic accuracy, scan efficiency, and patient comfort for a wide range of clinical applications, including body DWI. It will also enable shimming on wide- bore and PET/MR scanners, which do not have SH shim coils, and will eliminate the need for such coils in future scanners, resulting in lower manufacturing costs and a wider magnet bore to fit larger patients.