[图像]由日本跨国公司东芝进行磁共振成像扫描仪的一个示例。俄罗斯的研究人员最近提出了一种改良的扫描仪设计，可以更有效地检查小区域。信用：Mos.ru，Wikimedia（CC By 4.0）
在医疗技术方面，最具标志性的设备之一是磁共振成像（MRI）扫描仪。
MRI is a noninvasive medical imaging technique used to diagnose a variety of conditions, from torn ligaments to tumors. The technique relies on radio waves and a powerful magnet linked to a computer to create detailed pictures of areas inside the body. Compared to CT scans and X-rays, MRI does not use potentially harmful ionizing radiation.
下面说明的常规MRI扫描仪类似于一个大管，中间有一张桌子供患者躺在中。在管中，射频（RF）波通过大型人尺寸的大小传播给患者birdcage coil，，，，which consists of two circular conductive loops (called end rings) connected by several conductive straight elements (called rungs or legs). The MRI signal is detected by multiple receive-only surface coils that are located directly on a patient, and a cabling system delivers those signals to a spectrometer.
传统的MRI设计为检查整个身体以及某些身体部位和器官提供了可接受的图像质量。但是，对于专注于较小区域（例如头部，脊柱，关节和乳房）的检查，“身体鸟笼线圈的RF磁场分布在其总体积上，在激发期间需要较高的功率，以限制小线圈的传输效率。研究人员在最近的一个开放式纸。
研究人员来自俄罗斯的几家机构和公司，由助理教授领导Alexey Slobozhanyuk和首席研究员Anna Andreychenko来自圣彼得堡的Itmo大学。
In their paper, the researchers note that use of dedicated transceive coils, or coils that both transmit and receive, have proven useful to investigate some fine details, such as joints. But positioning of the coils can potentially breach the safety of the procedure during the transmit stage. “Also, the design of such coils restricts their only application to MR examinations of extremities,” they add.
These limitations are detrimental to early disease diagnosis capabilities, particularly in terms of detecting breast cancer. Breast cancer is女性最常见的癌症在美国，这是肺癌之后癌症死亡的第二大主要原因。但是，当早期检测到乳腺癌并处于局部阶段时，相对存活率为99％。美国癌症协会。
MRI is considered to provide the highest sensitivity to breast cancer, especially for younger women with dense glandular tissue, but unfortunately advanced magnetic resonance investigations are often unreliable or even unfeasible on a conventional clinical MRI scanner. Thus, design of an MRI scanner that can examine smaller areas more efficiently is sorely needed.
这样的扫描仪的设计正是俄罗斯研究人员在研究中的重点。他们描述并在实验上证明了靶向临床MRI的通用概念，并通过乳房成像证明了这一点。
The proposed MRI scanner design is a modification rather than overhaul of the conventional design. It involves electromagnetically coupling a dielectric resonator to the birdcage coil and passively focusing the RF magnetic field on a specific target area.
The researchers created the dielectric resonator using five ceramic discs made from magnesium-doped BaSrTiO3separated by a low dielectric constant material, in this case plastic. They varied the height of the resonator and the spacing between the discs to tune the device to an operational frequency of 3 Tesla (123.25 MHz). In addition, different separation of the dielectric discs allowed fine-tuning of the resonator’s spectral response without any additional lumped elements.
在体内研究上执行五个志愿者s, the researchers found that strong localization of the transmitting RF magnetic flux achieved using the new resonator led to an average 49-fold input power reduction compared to a conventional birdcage coil setup. Not only did this reduction result in seven times lower patient exposure to local RF electric fields, it meant “the presence of metallic implants outside the area of examination would not restrict the MR examination.”
他们确实观察到乳房形状图像的某些偏差，这归因于谐振器和持有人的几何设计。他们写道：“可以在未来的工作中避免使用这种限制，并在柔软的泡沫中使用特殊的解剖学切割，”他们写道。
研究人员于2018年12月提交了专利（其设计）（RU2018146803U).
开放式报纸，发表在自然通讯， 是 ”Ceramic resonators for targeted clinical magnetic resonance imaging of the breast” (DOI: 10.1038/s41467-020-17598-3).