声通道上的肋骨对高强度聚焦超声在羊肝内形成凝固性坏死的影响

目的从有效性、安全性和剂量学的角度探讨声通道上的肋骨对高强度聚焦超声（HIFU）损伤山羊肝的影响。方法HIFU分别辐照声通道上有肋骨（对照组）和声通道上肋骨被手术切除（实验组）的羊肝。辐照结束后2d处死动物，观察靶区凝固性坏死形成情况，测量凝固性坏死的体积并计算能效因子（energy efficiency factor，EEF）。结果实验组的凝固性坏死形成率明显高于对照组，EEF远远小于对照组。结论声通道上的肋骨明显影响凝固性坏死的形成率和EEF，提高HIFU治疗受肋骨阻挡的肝癌的治疗效率非常重要。

Effect of ribs in high intensity focused ultrasound beam path on formation of coagulative necrosis in goat liver

Objective To explore the effect of ribs in high intensity focused ultrasound(HIFU) beam path on HIFU ablation of goat liver. Methods A model-JC focused ultrasound tumor therapeutic system was used. A 0.75 MHz focused transducer with 150mm aperture and 120mm focal length was used in all experiment. Acoustical power can be adjusted. Twenty goats were divided into control group(HIFU beam through rib cage) and experiment group(Ribs in HIFU beam path were surgically removed). Twenty targeted regions at 50mm away from skin surface were applied for creating necrosis with linear scanning of 15mm length using HIFU in two groups. All animals were sacrificed two days later and targeted organs were dissected. After obtaining the maximal section, the volumes of the necrotic regions were measured, then to calculate energy efficiency factor(EEF). Results For experiment group, the proportion of formed coagulative necrosis relative to number of targeted region to be treated was bigger than control group, and EEF was more smaller than control group. Conclusions Ribs in HIFU beam path affected markedly the formation of coagulative necrosis and enhanced EEF, that indicate that the treatment efficiency can be decreased when treating liver cancer shielded by ribs with HIFU.