AI 中文总结
该研究提出无线体积超材料谐振器，将现有临床MRI的脊柱线圈转为乳腺MRI接收平台，可提升乳腺成像中心信噪比、降低空间不均匀性，为改善乳腺MRI性能提供了可行硬件方案。
AI 中文摘要
高性能乳腺磁共振成像（MRI）仍受限于专用接收线圈的可用性、几何形状及成本。相比之下，脊柱线圈在全球MR扫描仪中广泛安装，但对前部乳腺组织的灵敏度不足。本文报道一种无线体积超材料谐振器（VMR），可将标准内置脊柱线圈转换为可扩展的乳腺MRI接收平台，无需修改扫描仪硬件。VMR由轴向堆叠的同轴谐振环组成，支持同旋集体模式，在封闭成像体积内产生集中的射频磁场。利用同轴电缆的分布式电容、间隙设计的几何调谐及基于PIN二极管的自失谐，VMR实现了尺寸可扩展性、电场约束及收发兼容性，这通过台架测试和3.0T MRI实验得到验证。设计并评估了覆盖小、中、大三种乳腺等效体积的三个VMR原型，采用电磁仿真、台架测试和体模MRI实验。与商用16通道乳腺线圈相比，VMR增强型脊柱线圈在目标成像区域内中心信噪比（SNR）提高4倍以上，空间不均匀性从约70%降至20%。在SENSE并行成像加速因子为2-4时，三种尺寸的VMR增强型脊柱线圈中心SNR仍比商用线圈平均高4倍。这些结果确立了VMR作为一种被动、可扩展的硬件策略，可利用现有临床扫描仪基础设施提升乳腺MRI性能。
英文摘要
High-performance breast magnetic resonance imaging (MRI) remains limited by the availability, geometry, and cost of dedicated receive coils. In contrast, spine coils are widely installed in MR scanners globally but provide insufficient sensitivity for anterior breast tissue. Here, we report a wireless volumetric metamaterial resonator (VMR) that converts a standard built-in spine coil into a scalable breast MRI receiver platform without modifying the scanner hardware. The VMR consists of axially stacked coaxial resonant rings that support a co-rotating collective mode, producing a centrally concentrated RF magnetic field within the enclosed imaging volume. Leveraging distributed capacitance in the coaxial cable, gap-engineered geometric tuning, and PIN-diode-based self-detuning, the VMR enables size scalability, electric-field confinement, and transmit-receive compatibility, as validated through bench measurements and 3.0 T MRI experiments. Three VMR prototypes spanning small, medium, and large breast-equivalent volumes were designed and evaluated using electromagnetic simulations, bench measurements, and phantom MRI experiments. Compared with a commercial 16-channel breast coil, the VMR-augmented spine coil achieved more than 4-fold higher central SNR and reduced spatial non-uniformity from approximately 70% to 20% within the target imaging region. Under SENSE parallel imaging at acceleration factors of 2-4, the VMR-augmented spine coil maintained an average 4-fold higher central SNR than the commercial coil for three sizes. These results establish the VMR as a passive, scalable hardware strategy for improving breast MRI performance using existing clinical scanner infrastructure.
