A comparative study of establishing rabbit vertebral tumor model by two ways of CT-guided percutaneous puncture.

OBJECTIVE: To investigate the difference of tumor formation rate of rabbit vertebral tumor model established by percutaneous injection of V×2 tumor tissue suspension and tumor mass under computed tomography (CT) guidance, and the imaging findings of CT, magnetic resonance images (MRI) and positron emission tomography with computed tomography (PET/CT) at 7 days, 14 days and 21 days after implantation, and preliminarily verify the safety and feasibility of microwave ablation (MWA), percutaneous vertebroplasty (PVP) and microwave ablation combined with percutaneous vertebroplasty (MWA + PVP) in rabbit VX2 vertebral tumor model.

METHODS: Thirty healthy New Zealand rabbits were randomly allocated to tissue suspension group and tumor block group, with 15 rabbits for each group. The VX2 tumor block and mixed suspension were inoculated into the L5 vertebral body under CT-guided percutaneous puncture. The PET/CT, MRI and CT examinations were performed at 7, 14 and 21 days after implantation. Fisher exact probability test was used to compare the success rate of the two implantation methods and the tumor display rate at each time point of the three examination methods. Observe the paralysis of tumor-forming rabbits, and immediately perform MWA/PVP/MWA + PVP treatment according to groups after paralysis to verify the safety and feasibility of treatment.

RESULTS: A total of 18 experimental rabbits were successfully modeled in two groups, of which the success rate was 26.6% (4/15) in tissue suspension group and 93.3% (14/15) in tumor block group, with statistically significant differences between two groups (P < 0.01). The tumor display rates by PET/CT, MRI and CT at each time point after implantation were: 83.3% (15/18), 16.6% (3/18), and 0% (0/18) at 7 days after implantation; 100% (18/18), 88.8% (16/18), and 11.1% (2/18) at 14 days after implantation; and 100% (18/18), 100% (18/18), 77.7% (14/18) at 21 days after implantation. The average paralysis time of 18 experimental rabbits successfully modeled was 24.44 ± 2.38 days, and MWA/PVP/MWA + PVP treatment was performed in groups immediately after paralysis. Except for 2 rabbits who died due to anesthesia overdose during anesthesia before treatment, the remaining 16 rabbits were successfully treated with MWA/PVP/MWA + PVP, and the technical success rate was 100% (16/16). In MWA group, one experimental rabbit was randomly selected and killed after ablation, and histopathological examination (H and E staining) was performed together with 2 experimental rabbits who died of anesthesia. The pathological changes before and after ablation were compared. The survival time of the remaining 15 experimental rabbits varied from 3 to 8 days after treatment.

CONCLUSION: The success rate of establishing rabbit vertebral tumor model by injecting tumor masses under the CT-guided percutaneous puncture is high, and the following MWA and PVP treatment can be successfully conducted. PET/CT is the most sensitive method for early detection of tumor compared with MRI and CT. Spectral Presaturation with Inversion Recovery (SPIR) sequence can significantly improve the detection rate of smaller tumors by MRI and shorten the detection time.