Purpose

To determine whether histotripsy can create human-scale transcostal ablations in porcine liver without causing severe thermal wall injuries along the beam path.

Materials and Methods

Histotripsy was applied to the liver using a preclinical prototype robotic system through a transcostal window in six female swine. A 3.0 cm spherical ablation zone was prescribed. Duration of treatment (75 min) was longer than a prior subcostal treatment study (24 min, 15 s) to minimize beam path heating. Animals then underwent contrast-enhanced MRI, necropsy, and histopathology. Images and tissue were analyzed for ablation zone size, shape, completeness of necrosis, and off-target effects.

Results

Ablation zones demonstrated complete necrosis with no viable tissue remaining in 6/6 animals by histopathology. Ablation zone volume was close to prescribed (13.8 ± 1.8 cm³ vs. prescribed 14.1 cm³). Edema was noted in the body wall overlying the ablation on T2 MRI in 5/5 (one animal did not receive MRI), though there was no gross or histologic evidence of injury to the chest wall at necropsy. At gross inspection, lung discoloration in the right lower lobe was present in 5/6 animals (mean size: 1 × 2 × 4 cm) with alveolar hemorrhage, preservation of blood vessels and bronchioles, and minor injuries to pneumocytes noted at histology.

Conclusion

Transcostal hepatic histotripsy ablation appears feasible, effective, and no severe injuries were identified in an acute porcine model when prolonged cooling time is added to minimize body wall heating.

中文翻译：

---

活体急性肝猪模型中的经肋组织切除术消融

目的

确定组织切除术是否可以在猪肝脏中进行人体规模的经肋消融，而不会沿光束路径造成严重的热壁损伤。

材料和方法

使用临床前原型机器人系统通过六头雌性猪的经肋窗将组织切除术应用于肝脏。规定了一个 3.0 厘米的球形消融区。治疗持续时间（75 分钟）比之前的肋下治疗研究（24 分钟，15 秒）更长，以最大限度地减少光束路径加热。然后对动物进行对比增强 MRI、尸检和组织病理学检查。分析图像和组织的消融区大小、形状、坏死的完整性和脱靶效应。

结果

通过组织病理学，消融区在 6/6 动物中显示完全坏死，没有剩余的活组织。消融区体积接近规定（13.8 ± 1.8 cm ³与规定的 14.1 cm ³）。在 5/5 的 T2 MRI 上观察到消融覆盖的体壁水肿（一只动物没有接受 MRI），尽管尸检时没有胸壁损伤的肉眼或组织学证据。在大体检查中，5/6 动物（平均大小：1 × 2 × 4 cm）的右下叶肺变色，肺泡出血，血管和细支气管保留，组织学发现肺细胞有轻微损伤。

结论

经肋肝组织切除术消融似乎可行、有效，并且当延长冷却时间以最大程度地减少体壁加热时，在急性猪模型中未发现严重损伤。