A Novel Intravertebral Tumor Model In Rabbits By Transplantation Of VX₂ Carcinoma Via Percutaneous Puncture Under CT Guidance

OBJECTIVE:The purpose of the present study was to establish an animal model of metastatic spinal tumors by transplanting VX2 carcinoma into a lumbar vertebral body with computed tomographic [CT] guided percutaneous puncture technique and to analyze the onset of the paraplegia, radiographic changes (magnetic resonance imaging [MRI] and CT scans), and histopathological findings after intraosseous transplantation of VX2 carcinoma pieces into the lumbar vertebrae of rabbits.METHODS: New Zealand white rabbits (n = 30) were transplanted with VX2 carcinoma in the lumbar vertebral body with CT guided percutaneous puncture technique. Lower extremity motor function was assessed twice daily. MRI(T2-weighted and T1-weighted +gadolinium) and CT scans were acquired on postoperative day (POD) 14,21,28 and at the onset of paraparesis.When the vertebral tumors were detected by MRI and CT scans on POD 21 or 28, one of these animals without paraparesis were killed randomly and the spines were dissected respectively.After demineralization, the hematoxylin and eosin cross sections were obtained.The other animals were sacrificed and the spines were dissected at the onset of paraparesis.By the termination of the experiment on POD 90, the remaining animals without paraparesis were sacrificed after CT and MRI scans, and the actual conditions of the tumor were evaluated based on the axial localization from the inoculation position of the spinal tumor.The histological studies were also performed.RESULTS: The success rate of vertebral tumor in the experiment were 90%(27/30). Paravertebral tumor was revealed in one rabbit and no tumor was showed in two rabbits. Before the onset of paraparesis, the CT and MRI scans could reveal gross tumor. MRI scans revealed vertebral tumor in one rabbit without paraparesis on POD 14. MRI and CT scans revealed vertebral tumor in 20 rabbits on POD 21, of whom 18 rabbits were no paraparesis.The vertebral tumors were detected in another 6 rabbits by MRI and CT scans on POD 28, including 5 rabbits without paraparesis.The earliest day of paraparesis was POD 19, the latest was POD 36, and the mean onset of paraparesis was 26.4±4.2 days. CT scans demonstrated an osteolytic tumor centered in the vertebral body, and MRI scans showed epidural tumor arising from the body and compressing the spinal cord. Histopathological examination confirmed carcinoma arising from the body and extending into the canal, with widespread osteolytic activity.CONCLUSION: A novel intraosseous intravertebral tumor model in rabbits confirmed by CT, MRI and histopathology, was established via percutaneous puncture under CT guidance.The method was easy and feasible with very high success rate.The vertebral tumors could be revealed by CT and MRI in most of rabbits from POD 21.