| Objective1. To analyze the correlation with CEUS, CECT and histopathology through observing the findings of hepatic VX2 tumor in rabbits after RFA on CEUS, CECT and histopathology. To explore the reliability of CEUS in assessing the response of hepatic tumors after RFA compared with CECT and histopathology.2. To explore the clinical value of CEUS in treatment of HCC with RFA.Methods1. RFA was applied to 30 rabbit hepatic VX2 tumors. Both CEUS and CECT were performed 1 week after RFA in 30 rabbit models with hepatic VX2 tumor and followed with histopathologic examination. The largest diameters and perpendicular diameters of all ablation areas after RFA on CEUS were compared with that of CECT and fresh specimens. According to the results of histopathology, the sensitivity, specificity and accuracy for evaluating therapeutic effect were compared between CEUS and CECT.2.84 patients with 105 HCC lesions underwent CEUS before and after RFA and the usefulness of CEUS was evaluated before, during and after RFA, respectively. The final diagnosis was achieved by more than 3 months'follow-up of imaging examinations and tumor marker or biopsy.Results1. Residual viable tumors were found in 22 models and no residual tumors were seen in 8 models after RFA according to histopathology. Residual viable tumors showed enhancement in the arterial phase on both CEUS and CECT. Four types of tissue could be seen on the histopathologic sample, and from inner portion to outer portion were necrosis area, fibrous zone, remnant tumor and hepatic tissue which surrounding the RFA focus. The average largest diameter and perpendicular diameter and area of ablation areas were 1.37±0.34cm,1.02±0.37cm and 1.52±0.90cm on CEUS, respectively. Those of ablation areas were 1.32±0.37cm,0.95±0.37cm, 1.38±0.88cm and 1.27±0.35cm,0.94±0.34cm,1.31±0.77cm on CECT and sample, respectively. There was no statistical significance between CEUS and CECT(P> 0.05). There was no statistical significance between CEUS and histopathologic sample(P>0.05). According to the results of histopathology, the sensitivity, specificity and accuracy for evaluating therapeutic effect were 90.9%,75.0%,86.7% for CEUS and 86.4%,87.5%,86.7% for CECT, respectively. There was no statistical significance between CEUS and CECT(P>0.05).2. Before RFA:the boundary of 95.2%(100/105) lesions could be demarcated at CEUS, but the boundary of 47.6% (50/105) lesions could be demarcated at conventional ultrasound. The average largest diameter and area were 2.3±0.9cm and 5.0±4.1cm2at conventional ultrasound, and they were 2.5±0.9 cm and 6.1±4.5 cm2 at CEUS. The size of the lesions measured was larger at CEUS than at conventional ultrasound (P<0.05). Bearing cancer blood vessels were detected with CEUS, CECT and CDFI in 61.0%,42.9% and 25.7% lesions. During RFA:One HCC patient with one lesion could not be displayed at conventional ultrasound was treated with RFA by CEUS guidance. Residual viable tumors were visible at immediate CEUS after RFA in 3 patients with 3 lesions, and additional treatment with RFA was accomplished by CEUS guidance.20 patients with 26 lesions in all patients received CECT within 24 hours after RFA, and the diagnostic agreement between immediate CEUS and CECT was achieved in 96.2%. After RFA:81 among all patients were followed up, and 47 of the 81 patients underwent CECT at the same time. According to the final diagnosis, The sensitivity, specificity and accuracy for evaluating therapeutic effect were 84.6%, 95.4%,94.0% for CEUS and 90.9%,93.8%,93.2% for CECT, respectively. There was no significant difference in sensitivity, specificity and accuracy between CEUS and CECT (P>0.05).Conclusion1. Hepatic tumor of VX2 rabbits is alike humans HCC, and it can copied easily and successfully. Therefore, VX2 rabbit is the ideal animal model for research of human HCC, including radiological study of local effect after RFA. CEUS is sensitive to capillary vessel. It can accurately discriminate the coagulation necrosis from residual tumors after RFA and offer the reliable foundation for subsequent treatment.2. CEUS is safe, useful and effective, no matter before, during and after RFA. Its clinical value is significant.
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