Establishment And CT Evaluation Of Rabbit VX2 Hepatic Tumor Model

Objective: To evaluate the feasibility of the rabbit VX2 hepatic tumor model for imaging study, and to analyze its imaging features with spiral computed tomography (SCT).Materials and methods: A tumor was implanted into the liver of each of the 20 New Zealand white rabbits using a midline laparotomy. Hepatic tumor were created by injecting fragments of VX2 tumor into the left lobe of the liver. Plain CT scan and contrast-enhanced CT scan were performed at the 7th, 14th, 21st, 28th and 35th days after implantation respectively, and the dynamic contrast-enhanced CT were performed at a single level centered over the lesions at the 14th and the 21st days respectively. The observations were included: (1) The number of the lesions detected on CT; (2) The size of the lesions; and its metastases to other sites. (The growth rate of tumors was also calculated); (3) The histopathological features of tumors; (4) The spiral CT features of tumors; (5) Peak value (PV), peak time (PT) and the time-density curves (D-TC) of aorta, liver and tumor.Results: The success rate of transplanting tumor was 100%. Three lesions were detected by CT at the 7th day after implantation. The diameter and volume grew slowly at the 14th and the 21st day after implantation, but grew quickly at the 28th and the 35th day after implantation. The tumor grew as exponential curve. Metastases were found at the 28th day after implantation. Histopathological examination showed the tumor grew in the liver tissue and infiltrated into surrounding liver, and it had the similarbiological features with squamous cell carcinoma. The tumor appeared as a hypodensity solitary lesion in unenhanced CT except 2 (10%) lesions to be homogeneous density during the 14th and the 21st day. In arterial phase, significant peripheral enhancement were observed, the dilated nutritional arteries stretching straight to the margins in 15 (75%) lesions, while the mainbodies of tumors remained hypodensity. In portal phase and equilibrium phase, concentrically enhancement of tumors were detected. The density of tumors became heterogeneous on plain CT scan at the 21st day after implantation. PV of aorta, liver and tumor was 316.3~486.3HU, 55.3~77.3HU, 26.5~111.8HU respectively. PT of the tumors is earlier than that of the surrounding liver tissues.Conclusions: 1. Metastatic rabbit VX2 liver tumor model is stable and easy to be established. Its growth cycle and success rate of transplanting are satisfactory. It is also a suitable model for imaging study. 2. The characteristics of the blood supply, the histobiological and pathophy-siological features are similar to that of the hepatic cell carcinoma. 3. The position, number and the characteristic of growth and metastases can be detected by spiral CT at the 14th day after implantation. The blood supply of the tumor can be delineated by contrast enhanced CT and single lever dynamic SCT effectively and accurately. But the sensitivity of the SCT is lower within 7 days after the implantation. 4. SCT provides a method to evaluate the characteristic and the therapeutic effect of metastatic rabbit VX2 liver tumor model.