LAUSR

Abstract Cryosurgery is a new alternative surgical treatment compared with other traditional methods. However, it is hampered to standard cancer treatment due to some limitations. One is difficult to accurately monitor the extent of frozen tissue of internal organs during treatment. Another is insufficient freezing effect in the edge of the frozen region which leads to recurrence and metastasis of tumors. The approach of magnetic resonance imaging (MRI) is used to overcome such type of drawbacks during cryosurgery. The reason is that MRI could be explored to guide the puncture process and also monitor the developed frozen region throughout the cryoablation. Also, the iceball monitoring approaches could help to reduce the cell death of non-cancerous tissues. However, none of the studies enunciated the MRI compatible liquid nitrogen (LN2) cryoprobe based cryosurgery system to demonstrate the thermal evaluation during the treatment of carcinoma tissue. In this study, we established the MRI compatible LN2 cryoprobe based cryosurgery system to accurately destroying cancerous tissue while minimizing the destruction of healthy tissue. An unsteady two-phase flow and coupled heat transfer model was used to analyze the dynamics of the temperature fields developing in biological tissue during cryosurgery. The 3.0-T MRI system was applied to monitor the iceball propagation and detect the artifacts caused by the cryoprobe in cryosurgery. In vitro experiment was performed in porcine liver and further used in MRI approach. The results revealed that the ice ball diameter was approximately 4 cm determined by MRI approach after 500 s freezing both in phantom and porcine liver cases. Cell killing experiment with 0.1% (w/v) Fe3O4 nanoparticles was also conducted to overcome the edge effect and enlarge the effective killing region of entire iceball, found that there was no additional damage to the surrounding unfrozen tissue. All these methodologies show that the developed cryoprobe could be a potential to be adopted in MRI guided cryosurgeries that could be precisely watched the frozen propagation inside the diseased tissue. These findings may further promote the cryosurgery to be a more effective thermal treatment.