Imaging features of microwave-ablated lesions of the VX2 tumors in rabbit lungs on computed tomography and magnetic resonance images and their correlations with pathological examination.

PURPOSE: This study aimed to explore the accuracy of different imaging methods for lesion volume estimation pre- and post-microwave ablation (MWA) as compared with that of pathological examination. METHODS: We used the VX2 cell line to establish the VX2 lung tumor model in rabbits, followed by MWA of the tumor. The imaging features of the VX2 tumors were documented. The volume of the tumors and the ablated lesions were measured and compared across imaging methods, using the pathological examination as reference. RESULTS: Tumors were successfully developed in 11 rabbits (age, 13.91 ± 1.38 weeks; weight, 2.15 ± 0.56 kg). The mean volume of the tumors was 2.05 ± 1.88 cm3. CT showed the strongest correlation with the pathologic examination results (r = 0.998, p<.001). MWA created three-layered structures that were delineated on MRI. The mean volume of the post-ablation lesion was 10.39 ± 8.93 cm3, and the measurement of the post-ablation volume on 3D-VIBE-T1WI showed the strongest correlation with the pathologic examination results (r = 0.991, p<.001). CONCLUSION: Both CT and MRI are capable of depicting lung tumors. In terms of post-ablation evaluation, MR images could provide more versatile information. The 3D-VIBE-T1WI sequence provides more precise lesion volume evaluation after ablation compared with other methods.

Evaluation of the correlation between infrared thermal imaging-magnetic resonance imaging-pathology of microwave ablation of lesions in rabbit lung tumors.

PURPOSE: This study aimed to evaluate the correlation between infrared thermal imaging-magnetic resonance imaging (MRI)-pathology of microwave ablation (MWA) of lesions in rabbit lung tumors. MATERIALS AND METHODS: MR-guided MWA was performed in nine VX2 tumor-bearing rabbits. Infrared thermal imaging, postoperative MRI, and pathological presentation were obtained and analyzed. The differences between the infrared thermal imaging-MRI-pathology of MWA were compared. RESULTS: The center of the ablated lesion exhibited a high signal on T1-Vibe, and an isointense envelope was observed; the center of the ablated lesion exhibited a low signal on fat-suppressed turbo spin-echo T2-weighted imaging (TSE-T2WI-FS) and bands of high signal surrounding it compared with before MWA. No statistically significant difference existed between the maximum diameter of the central low-signal area of the ablation zone on TSE-T2WI-FS after MWA, the high-signal area of the ablation zone on T1-Vibe after MWA, and the maximum diameter of the pathological coagulation necrosis area, as well as between the maximum diameter of the isointense signal area peripheral to the ablation zone on T1-Vibe after MWA, the high-signal area peripheral to the ablation zone on TSE-T2WI-FS, the maximum diameter at the 41°C isothermal zone on infrared thermal imaging, and the maximum diameter of the pathological thermal injury zone. CONCLUSIONS: MWA of malignant lung tumors had specific MRI characteristics that were comparable with postoperative pathology. Infrared thermal imaging combined with MRI can be used to evaluate the extent of thermal damage to lung VX2 tumors.