应用高强度聚焦超声表面层三维消融模式消融离体牛肝组织

目的探讨高强度聚焦超声（HIFU）靶组织表面层三维消融模式的应用价值。方法取37块新鲜牛肝组织，采用HIFU连续点打法扫描，靶组织体积为40minX30mmX24mm。对实验组（表面层消融组）从深度40~16mm由深至浅依次沿靶组织周边以不同声功率、间隔时间、点间距的参数组合进行扫描，对照组（完全消融组）在同一深度依次逐层完全消融各层面。以TTC染色判定坏死范围，组织切片HE染色判定坏死程度。对两组的辐照时间及能量消耗进行统计学分析。结果实验组靶组织周边形成边界清晰、较均匀的凝固性坏死带，与对照组靶组织周边坏死体积的差异无统计学意义（卢2．64，P〉O．05）。实验组的能量消耗在深度32mm、24mm层面低于对照组，而在深度40mm、16mm层面高于对照组（P均〈O．05）；辐照时间在各个深度与对照组的差异无统计学意义（P均〉O．05）；其总辐照时间和能量消耗均低于对照组（P均〈O．05）。结论消融离体牛肝组织时，应用HIFU新型表面层三维消融模式可降低总能量消耗、缩短消融时间，提高消融效率。

Application of surface 3D model in high intensity focused ultrasound ablation of ex vivo bovine liver

Objective To explore the application value of surface 3D ablation model using high intensity focused ultrasound (HIFU). Methods The volume of targeted tissue was 40 mm×30 mm×24 mm. Using HIFU successive spot-shaped exposures, 37 segments of ex vivo bovine liver were continuously ablated at the depth of 40 mm, 32 mm, 24 mm and 16 mm, respectively. Dose combination was investigated by varying generator power, ablative exposure time, interval time, lesion separation and slice separation. The target tissues were paired and divided randomly into experimental group (surface 3D ablation model) and control group (complete ablation model). The coagulation necrosis range and necrotic degree after ablation were assessed using TTC staining and HE staining. The exposure time and energy consumption in two groups were statistically analyzed. Results Surface 3D ablation model produced well defined and sharply demarcated necrosis barriers on the periphery of the target regions. The peripheral necrosis ranges in the two groups had no significant differences (t=2.64, P>0.05). The energy consumption in experimental group at 32 mm and 24 mm focal depth was lower than those in control group, and the energy consumption in experimental group at 40 mm and 16 mm focal depth were higher than those in control group (all P<0.05).The exposure time at each focal depth had no significant difference between the two groups (all P>0.05). The overall exposure time and overall therapeutic doses in experimental group were significantly lower than those in control group (all P<0.05). Conclusion Surface 3D ablation model may decrease the overall therapeutic doses, reduce overall exposure time and thus enhance HIFU efficiency of ex vivo bovine liver at the above conditions.