Functional CT in a rabbit model: evaluation of the perfusion characteristics before and after Ar-He cryoablation...

The objective of this study was to investigate the perfusion characteristics of rabbit liver tumours before and after Ar-He (argon-helium) cryoablation using functional CT and to evaluate the therapeutic effect of Ar-He cryoablation. VX-2 tumour was implanted into the livers of 30 New Zealand white rabbits. Two weeks after tumour implantation, Ar-He cryoablation was performed on these rabbits. Functional CT was performed on the rabbits before and after treatment on days 1, 5, 14, 21 and 35. In the meantime, five rabbits were killed, and the livers were removed for histopathological examination at each of the time points mentioned above. Perfusion characteristics of the tumour and hot spot, such as blood flow (BF), blood volume (BV) and permeability, were analysed based on multislice CT. Histopathological studies corresponding to functional CT were observed, and the therapeutic effects (whether the tumour disappeared completely or still remained) were judged. The two-tailed student's t-test was used to compare the differences between the effect of pre- and post-Ar-He cryoablation treatment on tumour perfusion parameters. After cryoablation treatment, the number of tumours exhibiting complete necrosis was 13 (52%), and their perfusion parameters, such as BF, BV and permeability values, were significantly lower than those before treatment (P < 0.05, P < 0.01 and P < 0.05, respectively). After treatment, the number of incomplete necrotic tumours was 12 (48%). In the earlier stage (within 14 days of treatment), the whole tumour perfusion parameters of BF, BV and permeability were significantly lower than those before treatment (P < 0.05). In the late stage (more than 14 days of treatment), the whole tumour perfusion parameters of BF, BV and permeability were not significantly different compared with the pretreatment results (P > 0.05). The hot spot perfusion parameters of incomplete necrotic tumours, such as BF, BV and permeability values, showed no significant differences compared with pretreatment (P > 0.05). Functional CT can measure the perfusion characteristics of hepatic tumours and is consistent with histopathological changes in the tumour after Ar-He cryoablation. Functional CT might also be accurate in judging the therapeutic effect of Ar-He cryoablation.