Evaluation of elasticity distribution of the ablation area in the liver tumor by shear-wave elastography

Abstract

Objective To evaluate the elasticity distribution of the ablation area in the liver tumor by shear wave elastography(SWE). Methods Twenty cases of hepatic tumor ablations were studied. Both SWE and contrast-enhanced ultrasound (CEUS) images were taken for each ablation zone at 2 hours and 1 day after operation. None-enhanced area in the portal phase of CEUS image was considered as the ablation zone. Young modulus of corresponding region of the ablation area were measured. Results Regular elasticity gradient was present in the ablation area at 2 hours and 1 day after operation.Highest Young modulus was observed in the center of the ablation zone and gradually decreased to the normal liver tissue. Young modulus in the center, interior, border of the ablation zone, liver tissue close to the border and the region that 1 cm away from the border were (192.2±32.4)kPa & (83.6±15.9)kPa, (116.7±15.44)kPa & (121.4±12.9)kPa, (61.9±8.74)kPa & (61.8±16.2)kPa, (25.3±7.64)kPa & (26.7±7.0)kPa, (12.9±7.44)kPa & (11.1±6.5)kPa, respectively.Significant difference was detected among the Young modulus of all regions in the ablatioin area at the same time point after operation(P 0.05). Liver tisstue close to the ablation border was harder than that at the region of 1 cm away from the border (P 0.05). Conclusions SWE can quantitatively evaluate the elasticity distribution of the ablation area. There is regular elasticity gradient in the ablation area at 2 hours and 1 day after operation, which keeps stable during this time window. Key words: Elastography; Radiofrequency ablation; Liver tumor