The real-time MRI (0.23T open scanner) guidance and monitoring in percutaneous laser ablation of liver tumors

【摘要】：正 Objective: To evaluate the ability of real-time optical instrument tracking system integrated to the MRI scanner as a guidance and monitoring facility in positioning instrument and monitoring ablation of liver tumors, and to describe the feasibility and safety of laser ablaring malignant liver tumors. Methods:Total 22 hepatic tumors in 14 patients (11 males, 3 females, mean age 63.5 years), of which 10 were metastases and 4 were primary hepatocellular carcinoma (HCC), were treated with total thermal ablation. 0.23T open MR scanner and Nd-Yag type laser device was used. Completely balanced steady state (CBASS) sequence was used for lesion location, and field echo (FE) T_1 sequence for thermal monitoring. A 18 G needle was used for initial approach.Results: All the lesions scheduled were successfully localized,targeted, and treated under the MRI guidance. All the treated patients were discharged 3 days after interventional therapy. With both T_1-and T_2-weighted sequences, the ablated liver tissues were exactly depictable and provided precise delineation of the ablated tissue volume. On post-procedure and follow-up contrast-enhanced MR images, the thermal ablated lesions appeared avascular and necrotic. MRI showed the size of initial tumor, and the size of the coagulative necrosis after procedure immediately and 3 days later, in which all except one were slightly larger than initial tumors respectively. There was statistically significant differences in mean maximum of necrosis diameter between intraprocedure and that of 3 days later on T_1-and T_2-weighted images. Conclusion: MRI-guided percutaneous laser thermal ablation of liver rumors is feasible and safe. The optical tracking system and intraprocedural thermal monitoring with MRI prove to be useful and reliable tools for estimating the effects of thermotherapy accurately.