实时剪切波弹性成像评价肝脏肿瘤射频消融的临床研究

Real-time shear wave elastography in the evaluation of radiofrequence ablation for liver tumours:a clinical study

目的探讨肝脏肿瘤射频消融前后的弹性变化以及实时剪切波弹性成像（SWE）对消融范围的显示能力。方法 2012年2月至2013年12月于中山大学附属第一医院行射频消融治疗并获得完全消融的肝脏肿瘤患者57例共57个病灶,平均直径（2.4±1.1）cm。分别于消融前及消融后30 min、1 d、1个月进行SWE,测量消融灶的杨氏模量最大值（SWE_max）、最小值（SWE_min）、平均值（SWE_mean）及离散度（SWE_SD）。比较肝脏肿瘤消融前后不同时间点的杨氏模量值。选择经Cool-tip射频消融系统持续消融12 min的消融灶,于消融后1个月分别在二维声像图、SWE图像上测量其长径和短径,根据公式V=π×X×Y×Z/6（V为体积,X为长径、Y=Z为短径）计算消融灶体积,与当天超声造影无增强区域范围进行比较。结果 （1）消融后30 min的SWE_max、SWE_min、SWE_mean及SWE_SD分别为（121.80±68.52）、（30.36±24.96）、（66.92±24.88）和（20.37±12.97）kPa,消融后1 d上述指标分别为（108.20±46.99）、（31.87±18.08）、（67.12±23.53）和（19.41±12.05）kPa,消融后1个月上述指标分别为（130.40±53.68）、（32.00±22.06）、（86.88±45.18）和（35.05±25.50）kPa,各参数分别大于消融前的（50.85±30.61）、（15.30±8.78）、（30.50±11.56）和（7.37±4.26）k Pa,差异均有统计学意义（Z=118-561,P均〈0.001,Wilcoxon符号秩和检验）;消融后30 min、1 d及1个月同一参数杨氏模量值比较,差异均无统计学意义（χ^2=3.088、0.821、5.202、3.786,P均〉0.05,Friedman非参数秩和检验）。（2）SWE图像示消融灶长径为（3.0±0.6）cm,与二维超声[（2.9±0.5）cm]比较,差异无统计学意义（t=0.538,P〉0.05）;但小于超声造影的（3.4±0.4）cm,差异有统计学意义（t=3.644,P〈0.01）。SWE图像示消融灶短径[（2.3±0.4）cm]及体积[（9.2±4.7）cm^3]与二维超声[（2.4±0.5）cm、（9.3±5.0）cm^3]及超声造影[（2.2±0.6）cm、（9.6±6.0）cm^3]比较,三者间差异均无统计学意义（F=0.581、0.067,P均〉0.05）。结论 SWE能够定量分析肝脏肿瘤射频消融前后的弹性变化,病灶消融后明显变硬,且硬度不随时间变化。此外,SWE对消融灶边界刻画清晰,且可近似估计消融范围,但是与实际消融范围仍存在一定偏差。

Objective To investigate the elasticity change of liver tumour before and after radiofrequency ablation（RFA） and the capacity of estimating ablation extent using real-time shear wave elastography（SWE）.Methods From February 2012 to December 2013,a total number of 57 patients with 57 lesions [mean diameter（2.4±1.1） cm] who carried out radiofrequency ablation and got complete response in affiliated hospital of Sun Yat-Sen University were enrolled.SWE examination was performed before,30 min after,1 day after and 1 month after ablation.The maximum,minimum,mean and standard deviation of SWE values of ablation zone were measured.The parameters at different time were compared.The ablation zones treated with Cool-tip radiofrequency system and duration 12 min were chosen（n=12）.The long and short diameters of ablation zone were measured on baseline ultrasound and SWE images at 1 month after ablation.The volume was calculated according to equation V=π·X·Y·Z/6（V volume,X long diameter,Y=Z short diameter）.The non-enhanced extent on contrast-enhanced ultrasound（CEUS） at the same day was used as reference.Results（1） The maximum,minimum,mean,standard deviation of SWE value at 30 min after ablation were（121.80±68.52） k Pa,（30.36±24.96） k Pa,（66.92±24.88） k Pa and（20.37±12.97） kPa,those at 1 day after ablation were（108.20±46.99） k Pa,（31.87±18.08） kPa,（67.12±23.53） k Pa and（19.41±12.05） kPa,those at 1 month after ablation were（130.40±53.68） k Pa,（32.00±22.06） k Pa,（86.88±45.18） k Pa and（35.05±25.50） k Pa.All of above parameters were higher than those before ablation：（50.85±30.61） k Pa,（15.30±8.78） kPa,（30.50±11.56） k Pa and（7.37±4.26） kPa（Z=118-561,all P 〈0.001 respectively,Wilcoxon sign ranked test）.No significant difference was found among each elasticity parameters at 30 min,1 day and 1 month after RFA（χ^2=3.088,0.821,5.202 and 3.786,all P〉0.05,Friedman test）.（2） The long diameter（3.0±0.6） cm of ablation zone on SWE was similar with that on baseline ultrasound（2.9±0.5） cm（t=0.538,P〉0.05）,but less than that on CEUS [（3.4±0.4） cm]（t=3.644,P〈0.01）.The short diameter [（2.3±0.4）cm] and volume [（9.2±4.7） cm^3] of ablation zone on SWE were not significantly different compared to those on baseline ultrasound [（2.4±0.5） cm and（9.3±5.0） cm^3] and those on contrast enhanced ultrasound [（2.2±0.6） cm and（9.6±6.0） cm^3]（F=0.581,0.067,both P〉 0.05,respectively）.Conclusions SWE can quantitively analyze the elasticity change before and after ablation.The ablation zone became stiffer after RFA,but no changes over time.The SWE can clearly show the boundary of ablation zone,but still have a discrepancy with the actual necrosis extent.