Experimental Study Of Functional CT For Ar-He Cryoablation Therapy Of Rabbit Liver Tumour Model

Objective: To investigate the perfusion characteristics of rabbit liver tumors before and after cryoablation on functional CT and evaluate the therapeutic effect of cryoablation. And study the correlation between CT perfusion and histomorphological markers of tumour angiogenesis.Methods: VX-2 tumour was implanted into the livers of 30 New Zealand white rabbits. 2 weeks after tumour implantation, Ar-He cryoablation was performed on these rabbits. Functional CT was applied on the rabbits before and after treatment on days 1, 5, 14, 21 and 35. In the meantime, 5 rabbits were sacrificed and the livers corresponding to functional CT were removed for histopathological examination at each of the time points mentioned above. Perfusion characteristics of tumour and hot spot such as blood flow (BF), blood volume (BV) and permeability were analyzed based on multi-slice CT (MSCT). Histomorphological markers of tumour angiogenesis (VEGF and MVD) were evaluated. The correlation between CT perfusion parameters and histomorphological markers of tumour angiogenesis were studied.Results: After cryoablation, the number of completed necrotic tumour was 13 (52%), and their perfusion parameters such as BF, BV and permeability values were significantly lower than that of pre-treatment (P<0.01, P<0.05 and P<0.05). The number of incomplete necrotic tumour was 12 (48%). In the earlier stage (within 14 days of treatment), the whole tumour perfusion parameters were significantly lower than those of pre-treatment (PO.05). The hot spot perfusion parameters had no significant differences compared with pre- treatment (P>0.05). VEGF was expressed in all tumors. No significant relationships were observed between VEGF and all CT perfusion parameters (P>0.05); Mean MVD was 60.78±22.07/ per field, and MVD had relationships with CT perfusion parameters (P<0.05).Conclusion: Functional CT can quantity the perfusion of liver tumour and might be used for tumour characterization as well as for therapy response monitoring. The CT perfusion parameters had some correlations with histomorphological markers of tumour angiogenesis, and could reflect tumour angiogenic activity, in some degree.