Purpose
We attempted to evaluate microvascular changes of hepatocellular carcinomas (HCCs) using SonoVue and a new contrast technique, Micro Flow Imaging (MFI) in terms of radiofrequency ablation therapy. We ultimately aimed to clarify whether this new method could be used for imaging assisting local ablation treatment of hepatocellular carcinoma (HCC).
Material and methods
The ultrasound contrast agent used was SonoVue. SonoVue was injected intravenously at the dose from 1.0 to 2.4 mL. A new contrast imaging mode was used for the study. MFI is accumulated imaging using the maximum folding technique following several flash scanning flames with a high MI ultrasound exposure. The ultrasound equipment used was Toshiba Aplio and the transducer used was a convex type, 375BT with a central frequency of 3.75 MHz. MFI was performed in 25 patients, in whom HCCs were treated with RFA. MFI studies were performed before and after RFA.
Results
Morphological MFI findings of HCC were divided into three patterns 1) cotton pattern- no thick blood vessels and cotton wool staining; 2) vascular and cotton pattern- continuous vascular images and cotton staining; 3) clubbed vascular pattern- clubbed vessels with fewer branches and heterogeneous staining. Cotton pattern was most frequently seen in well differentiated HCC, vascular and cotton pattern in moderately differentiated HCC and clubbed vascular pattern in poor HCC. The overall diagnostic accuracy was 77% when these criteria were applied to HCC diagnosis.The ablation area was more clearly demonstrated in MFI than the conventional harmonic imaging after RFA. The remaining blood vessels in and around the ablation area were depicted in a good continuity. There was no case in which the tumor staining was remained after RFA in the MFI and CT studies. The safety margin was accurately evaluated using MFI by comparing pre and post RFA images of MFI.
Conclusion
Microvascular morphology of HCC was visualized using MFI. Microvascular changes correlated well with the pathological differentiation of HCCs. The ablation area and remaining blood vessels after RFA were well evaluated in the MFI. MFI could be used for imaging assisting RFA of hepatocellular carcinoma.