MR-GUIDED FOCUSED ULTRASOUND ABLATION THROUGH THE RIBCAGE

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 简介：近年来，MR引导聚焦超声（FUS）消融已显示出作为治疗各种疾病的非侵入性替代方案的前景。对于上腹部和胸部中的FUS应用，主要限制是用于FUS递送的受限声窗，这是由于与软组织相比，胸椎和软骨的声阻抗较高。在这里，我们调查如果一个人类大小的胸腔提供足够的声学窗口消融组织的心脏。 方法和讨论：结果表明，最高消融温度随肋骨阻塞量而变化。相比之下，没有肋骨阻塞导致45 ℃的温度。小于约40%肋骨阻塞的区域达到超过30 ℃的温升，足以在活组织中产生组织坏死（最终温度> 55 ℃）。然而，在超过80%的光束路径被肋阻挡的区域测量到的温度升高低至5 º C。此外，对于大多数超声处理，发现所选超声处理位置和最大温升位置的偏移（成像平面中平均为5 mm）。这表明肋不仅衰减加热点，而且影响其位置和形状。观察到胸腔的表面加热，这突出了对自适应机制的需要，例如关闭单个换能器元件，其光束路径被肋骨阻挡。

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.