MR-GUIDED FOCUSED ULTRASOUND ABLATION THROUGH THE RIBCAGE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 前言：近年来，MR引导的聚焦超声(FUS)消融术有望成为治疗各种疾病的一种非侵入性选择。对于FUS在上腹部和胸部的应用，一个主要的限制是FUS交付的有限声学窗口，因为与软组织相比，胸骨和软骨的声阻抗更高。在这里，我们调查人类大小的胸腔是否提供了足够的声学窗口来消融心脏组织。 方法与讨论：结果表明，最高消融温度随肋骨阻塞量的不同而不同。作为对比，没有肋骨阻塞导致的温度为45℃。肋骨阻塞低于约40%的区域达到的温度上升超过30℃，足以在活体组织中造成组织坏死(最终温度&gt；55℃)。然而，在肋骨阻挡光束路径超过80%的区域，温度升高测量到低至5摄氏度。此外，对于大多数声学检查(在成像平面中平均为5 mm)，发现距所选声学位置和最大温升位置的偏移量。这表明肋骨不仅衰减了加热点，而且还影响了加热点的位置和形状。观察到了肋骨的表面加热，这突显了自适应机制的必要性，例如关闭单个换能器元件，使光束路径被肋骨遮挡。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Introduction: In recent years, MR-guided focused ultrasound (FUS) ablation has shown promise as a non-invasive alternative for the treatment of various diseases. For FUS applications in the upper abdomen and chest, a major limitation is the restricted acoustic window for FUS delivery, due to the higher acoustic impedance of thoracic bone and cartilage compared to soft tissues. Here, we investigate if a human size ribcage provides enough acoustic window to ablate tissue in the heart. Methods and Discussion: The results showed that the maximum ablation temperature varied with the amount of rib obstruction. For comparison, no rib obstruction resulted in a temperature of 45¿C. Areas with less than approximately 40% rib obstruction reached temperature rises of more than 30¿C, sufficient to create tissue necrosis in living tissue (final temperature > 55¿C). However, temperature elevations as low as 5¿C were measured in areas with more than 80% beam path obstruction by the ribs. In addition, an offset from the selected sonication location and the location of the maximum temperature rise was found for most sonications (average of 5 mm in the imaging plane). This suggests that the ribs not only attenuate the heating spot but also influence its position and shape. Surface heating of the ribcage was observed, which highlights the need for adaptive mechanisms such as turning off individual transducer elements with beam paths obstructed by ribs.