实时超声弹性成像评价离体牛肝组织内射频消融灶的实验研究

Preliminary results on visualization of radiofrequency ablation lesions using real-time ultrasound elastography with the bovine liver ex-vivo

目的探讨实时超声弹性成像评价离体牛肝组织内射频消融灶的可行性。方法取新鲜牛肝1只,切为6块作为形成射频消融灶的材料。采用RITA1500型射频治疗仪分别对6块牛肝组织行射频消融24次,按消融灶深度将实验分成3组:深1cm、3cm、5cm组,每组8个消融灶。消融结束后分别采用常规二维超声及实时超声弹性成像测量消融灶最大上下径、前后径及左右径,按椭球体公式计算消融灶体积,并与大体标本测量的体积进行比较。结果消融后实时超声弹性图像能显示16个消融灶呈均匀蓝色,与周边正常组织分界清楚。深1cm组二维超声,实时超声弹性成像和大体标本测量的消融灶平均体积分别为(514.8±63.4)mm3,(748.1±98.1)mm3,(766.3±43.2)mm3。深3cm组3种方法测量的消融灶平均体积分别为(498.1±154.9)mm3,(694.4±48.1)mm3,(707.5±25.0)mm3。深1cm与深3cm组二维超声、实时超声弹性成像与大体标本测量结果比较差异有统计学意义(P<0.05),二维超声无法准确估计消融灶的真实大小;而实时超声弹性成像能很好地反应深1cm和深3cm组消融灶的真实大小,其与大体标本测量体积之间具有较好的相关性(r=0.6064,P<0.05)。随着消融灶深度的增加,实时超声弹性成像获取消融灶图像的难度增大,当消融灶深度达到5cm时,该技术难以获取消融灶的弹性图像。结论实时超声弹性成像有望成为评价肝组织内射频消融灶形态及大小的有效方法,但应用时对消融灶深度有一定限制。

Objective To evaluate the reliability and feasibility of real-time ultrasound elastography for estimating the RFA-lesion boundaries in liver. Methods Bovine livers were chosen for this study. Twenty- four RFA were performed on bovine livers with different depth including 1 cm,3 cm and 5 cm. Each group had eight RFA-lesions. Gray-scale ultrasound and elastography were performed after the RFA. The imaging planes were perpendicular and parallel to the axis of the RF electrode. All the ultrasound and elastography images were stored in computer. Then the measurements of all the RFA-lesions were done. Measurements of the sections representing the same image planes used for elastography were taken at pathologic examination and compared with the measurements obtained from the gray-scale uhrasound images and elastograms. Results The average volumes of gray-scale ultrasound images, elastograms and pathologic measurements of 1 cm group were 514.8 ± 63.4 mm^3, 748.1 ± 98.1 mm^3,766.3 ±43.2 mm^3 respectively. The average volumes of 3 cm group were 498.1 ± 154.9 mm^3 ,694.4 ± 48. 1 mm^3 ,707.5 ± 25.0 mm^3 respectively. The RFA-lesions could not be evaluated by grey-scale ultrasound correctly（ P 〈0.05 ）. RFA-lesion boundaries in the elastograms were more clearer in 1 cm group and 3 cm group. We found a statistically significant correlation between elastography and pathology measurements（r =0. 6064,P 〈 0.05 ）. The RFA-lesions could not be estimated by lastography in case the depth increased to 5 cm. Conclusions Real-time ultrasound elastography may prove to be reliable for estimating the boundaries of the RFA-lesions and be useful for monitoring during the RFA procedure.