Assessment of Cerebral Microembolism During Percutaneous Radiofrequency Ablation of Lung Tumors Using Diffusion-Weighted Imaging

OBJECTIVE: It is well known that radiofrequency ablation generates microbubbles in the liver. We hypothesized that microbubbles generated during percutaneous radiofrequency ablation of lung tumors flow into the pulmonary veins and are distributed to the systemic arteries, as with radiofrequency ablation of liver tumors. To assess the risk of cerebral infarction during radiofrequency ablation of lung tumors, we performed diffusion-weighted imaging and, if possible, monitored microemboli in the carotid artery during radiofrequency ablation. SUBJECTS AND METHODS: We prospectively studied 20 patients (19 men and one woman) who underwent radiofrequency ablation of lung tumors. Pre- and postoperative MRI examinations were performed in all 20 patients, and during 17 radiofrequency ablation sessions, sonography was used to monitor whether microemboli were generated. RESULTS: Radiofrequency ablation was technically feasible for the treatment of selected pulmonary tumors. Microemboli, which were believed to represent microbubbles, were seen on sonography during three of the 17 radiofrequency ablation sessions. They were rarely observed when a lung tumor was small, the treatment session was brief, and the radiofrequency emission power was low. No new area of abnormal intensity was seen on postoperative MRI in all 20 patients. Although the microemboli were observed, MRI could not confirm infarction. CONCLUSION: We concluded that cerebral infarction as a result of microbubbles generated during radiofrequency ablation of lung tumors has a low possibility of becoming a clinical problem.