IEEE Trans Med Imaging. 2023 Aug;42(8):2425-2438. doi: 10.1109/TMI.2023.3250647. Epub 2023 Aug 1.
Microwave-induced thermoacoustic imaging (MTAI) using low-energy and long-wavelength microwave photons has great potential in detecting deep-seated diseases due to its unique ability of visualizing intrinsic electric properties of tissue in high resolution. However, the low contrast in conductivity between a target (e.g., a tumor) and the surroundings sets a fundamental limit for achieving a high imaging sensitivity, which significantly hinders its biomedical applications. To overcome this limit, we develop a split ring resonator (SRR) topology based MTAI (SRR-MTAI) approach to achieve highly sensitive detection by precise manipulation and efficient delivery of microwave energy. The in vitro experiments show that SRR-MTAI demonstrates an ultrahigh sensitivity of distinguishing a 0.4% difference in saline concentrations and a 2.5-fold enhancement of detecting a tissue target which mimicks a tumor embedded at a depth of 2 cm. The in vivo animal experiments conducted indicate that the imaging sensitivity between a tumor and the surrounding tissue is increased by 3.3-fold using SRR-MTAI. The dramatic enhancement in imaging sensitivity suggests that SRR-MTAI has the potential to open new avenues for MTAI to tackle a variety of biomedical problems that were impossible previously.
基于环形谐振器的微波激励热声成像技术（SRR-MTAI）通过精确操控和高效传输微波能量，实现了对目标（如肿瘤）的高灵敏度检测，有望解决深层疾病的检测问题。该技术利用低能量、长波长的微波光子，具有高分辨率可视化组织固有电特性的独特能力。然而，由于目标（如肿瘤）与周围组织之间的电导率对比度低，限制了成像灵敏度的提高，这极大地阻碍了其在生物医学中的应用。为了克服这一限制，我们开发了一种基于环形谐振器的微波激励热声成像技术（SRR-MTAI），通过精确操控和高效传输微波能量，实现了对目标的高灵敏度检测。体外实验表明，SRR-MTAI 能够区分 0.4%盐浓度差异，对深度为 2cm 的组织目标（模拟肿瘤）的检测灵敏度提高了 2.5 倍。体内动物实验表明，SRR-MTAI 可将肿瘤与周围组织之间的成像灵敏度提高 3.3 倍。这种成像灵敏度的显著提高表明，SRR-MTAI 有望为 MTAI 开辟新途径，解决以前无法解决的各种生物医学问题。
