Hepatic Tumors After Microwave Ablation Local Acoustic Radiation Pulse Imaging Changes

Objective Investigating the clinical value of ARFI (acoustic radiation force impulse) after the microwave ablation of hepatic malignancies by observing the performances and changes of ablation zone, the edge and surrounding of liver parenchyma in ARFI which consists of VTI (virtual touch tissue imaging) and VTQ (virtual touch tissue quantification).Materials and Methods Executing ARFI imaging, conventional ultrasound and contrast-enhanced ultrasound(CEUS)on the liver cancer nodules in22liver cancer patients, who have been treated by the ultrasound-guided percutaneous microwave ablation. We analyzed the time intensity accordingly, followed up the patients after microwave ablation regularly and ran the enhanced MRI examination on the people who were suspected with residual tumor or local recurrence. Meanwhile we made a definite diagnosis with biopsy. Finally we compared the stiffness differences between the lesions and the surrounding of liver parenchyma before and after the treatment, as well as the size of ablation zone displayed on VTI, conventional ultrasound and CEUS and observed the stiffness changes and contrast perfusion in microwave ablation zone and its edge.Results1. In the22cases of liver cancer patients, only2patients showed X.XX m/s in VTQ values and for the rest20patients, there were no significant statistical differences in VTQ values between the lesion and the surrounding liver parenchyma(Z=0.523,P=0.601).2. All VTQ values in ablation zone were X.XX m/s. There were no significant differences in determining the sizes of ablation zone displayed on VTI, conventional ultrasound and CEUS.3. After microwave ablation of hepatic malignancies, the VTQ values on the edge of ablation zone were larger than that on the surrounding of liver parenchyma. There were significant differences in3days(t=2.971,P=0.003),3months(t=3.408,P=0001),6months (t=3.351,P=0.001)and lyear after ablation(t=3.69,P=0.002).4. The VTQ values on the edge of ablation zone decreased gradually in3days,3months,6months and1year after the microwave ablation, but there were no significant differences between them(F=0.847,P=0.474).5. The relationship between the VTQ values on the edge of ablation zone and the analyzed parameters of Wash/in-Wash/out time intensity curve:3days after the ablation:there were significantly positive correlation between VTQ values and mean transit time(MTT)(r=0.940, P=0.017),lyear after the ablation:there were significantly positive correlation between VTQ values and time to peak intensity (PIT)(r=0.752, P=0.001).6. One patient presented local recurrence during the Follow-up.Conclusion ARFI plays a potential role in estimating recurrence by observing the shape and range of coagulation necrosis, and the changes of stiffness in the surrounding tissues of ablation zone in a short time after microwave ablation of liver malignancies, and expected to be one of the effective assessments of thermal ablation of hepatic tumor.