磁共振引导高强度聚焦超声消融犬肾上腺的可行性研究

Experimental study on MRI-guided high-intensity focused ultrasound ablation of adrenal glands in dogs

目的探讨磁共振(magnetic resonance imaging,MRI)引导高强度聚焦超声(high intensity focused ultrasound,HIFU)体外消融肾上腺的可行性。方法 16只体质量9～13 kg的健康杂种犬,随机分为对照组(n=4)、相对低能量HIFU消融组(声功率200 W组,n=6)、相对高能量HIFU消融组(声功率400 W组,n=6),在MRI引导下消融左侧肾上腺。术后利用MRI增强造影,观察肾上腺消融情况以及周围脏器损伤情况。术后每天动态监测各组血液中皮质醇、醛固酮激素的含量。5 d后处死实验犬,对左侧肾上腺进行大体及病理学观察,评估200、400 W声功率下肾上腺消融面积以及消融比的差异。结果 HIFU消融术后犬生命体征平稳,MRI增强造影可见消融区域肾上腺信号明显减低,周围脏器组织未见明显信号异常。大体观察可见左侧肾上腺头部和尾部出血、肿胀及部分液化,消融区域皮肤及肾上腺周围脏器均未见明显损伤。病理检查可见消融区域肾上腺出现凝固性坏死灶,与周围组织分界清楚。400 W组消融灶数量要明显多于200 W组的消融灶。200 W组消融灶面积为(1.8±0.3)cm2,消融比率为(40.3±18.1)%;400 W组消融灶面积为(2.7±0.6)cm2,消融比率为(60.3±23.3)%,2组间消融面积和消融比率差异有统计学意义(P<0.05)。术后第1天与对照组相比,血液中皮质醇及醛固酮出现一过性升高,第2天开始出现下降趋势,第4～5天趋于稳定。2声功率组激素含量从第3天开始均与对照组存在统计学差异(P<0.05)。结论 MRI引导HIFU技术可以实现活体动物肾上腺消融,消融范围可控,在肾上腺疾病外科无创治疗方面可能有应用前景。

Objective To evaluate the feasibility of extracorporeal ablation of adrenal glands by magnetic resonance imaging （MRI）-guided high-intensity focused ultrasound （HIFU）. Methods Sixteen healthy mongrel dogs weighing 9 - 13 kg were randomly divided into a control group, a low-dose HIFU ablation group （ acoustic power 200 W） and a high-dose HIFU ablation group （ acoustic power 400 W） , respectively. All the dogs underwent MRI-guided extracorporeal HIFU ablation of their left adrenal glands. After the ablation, en- hanced MRI was used to evaluate the damage to the adrenal glands and adjacent organs and tissues. The levels of aldosterone and cortisol were monitored every day. All the dogs were sacrificed after 5 d, and the destruction of the left adrenal glands and adjacent organs and tissues were observed. The ablation of the adrenal glands was assessed by hematoxylin and eosin （HE） staining. The difference of the ablation ratio between the low-dose HI- FU ablation group and the high-dose HIFU ablation group was evaluated. Results After ablation, the vital signs of all the dogs were stable. Enhanced MRI showed a significant signal decrease in the ablation regions of the adrenal glands and no obvious abnormal signal in adjacent organs and tissues. The ablation lesions in the head and tail of the left adrenal glands could be seen clearly. HE staining showed the ablation lesions of adrenalglands had pathological necrosis and a clear demarcation to the surrounding tissues. The number of the ablation lesions of the high-dose HIFU ablation group was significantly greater than that of the low-dose HIFU ablation group. The average ablation area of the low-dose HIFU ablation group was 1.8 ± 0.3 cm2 with an average abla- tion ratio of （40.3±18.1 ） %. The average ablation area of the high-dose HIFU ablation group was 2.7± 0.6 cm2 with an average ablation ratio of （60.3±23.3）%. The ablation area and ablation ratio of the high-dose HIFU ablation group were significantly higher than those of the low-dose HIFU ablation group （P 〈0.05 ）. Compared with the control group, the levels of aldosterone and cortisol of the low-dose HIFU ablation gronp and the highclose HIFU ablation group both showed Iransient increases at the first day, and then a decrease trend from the second day. From the third day, they both tended to be stable but were still lower than those of the conhul group （P 〈0.05 ）. Gonclusion MRI-guided HIFU is a sale and effective method to achieve controllable ablatiuu of adrenal glands, and HIFU may have potential application in minimally invasive treatment of adrenal diseases.