Shear Wave Elastography in Evaluating the Efficacy of Liver Microwave Ablation: An Experimental Study

Abstract

Background: The effect of microwave ablation on small hepatocellular carcinoma is not significantly different from that of surgical resection. Accurate assessment of the ablation effect is crucial for ensuring the safety and effectiveness of hyperthermia. Objectives: This study aimed to explore the feasibility and accuracy of supersonic shear wave elastography (SWE) in quantitatively evaluating the microwave ablation margin of the liver. Materials and Methods: Three surgeons were each randomly assigned 4 Wuzhishan miniature pigs (WZSPs) to perform 12 ablation procedures at an ablation power of 40 W. Based on the ablation time, the lesions were divided into 15, 30, and 60-second groups. Immediately after ablation, SWE and modulus measurements were performed 5 times for each ablation lesion. The SWE data were expressed as mean ± standard deviation. Within-group and between-group comparisons were made using repeated measures analysis of variance. Results: A total of 144 effective ablations and 131 effective pathological results were obtained. Within the same ablation time, the elastic modulus increased in the surrounding normal tissue, ablation margin, and ablation center regions in a stepwise manner (P < 0.01). However, in the ablation center region, the elastic modulus decreased in a stepwise manner with the shortening of ablation time [60 s (97.16 ± 14.58 kPa) > 30 s (77.84 ± 9.64 kPa) > 15 s (38.92 ± 3.12 kPa)], with statistically significant differences (F = 2,131.832, P < 0.01). The elastic modulus of the ablation margin region at different ablation times remained between 22.68 - 23.56 kPa. Conclusion: The elastic modulus range in the ablation margin region after microwave ablation is relatively fixed. Shear wave elastography aids in the quantitative evaluation of the ablation margin region of the liver and has high practical value in monitoring and evaluating ultrasound ablation.