Evaluation of cerebral microemboli during radiofrequency ablation of lung tumors in a canine model with use of impedance-controlled devices.
OBJECTIVE
To evaluate the incidence of cerebral microemboli during radiofrequency (RF) ablation of lung tumors in a canine model and evaluate the adverse effects of these microemboli on the brain parenchyma with use of magnetic resonance (MR) imaging and histopathologic examination.


METHODS
Percutaneous RF ablation of 12 lung tumors in 12 dogs was performed under computed tomography (CT) guidance with use of impedance-controlled devices. The common carotid artery was continuously monitored in each animal during RF ablation with duplex Doppler ultrasonography. All animals underwent brain MR imaging shortly after RF ablation. Delayed brain MR imaging (5-8 days after RF ablation) was performed in eight animals. The MR examinations included diffusion-weighted echo-planar imaging. The animals were euthanized 3-11 days after RF ablation. The brain was harvested from each animal and examined by an experienced veterinary pathologist for evidence of ischemia.


RESULTS
RF ablation was technically successful in all animals. Microbubbles were detected in the carotid artery in two animals (17%). Acute and delayed MR studies demonstrated no evidence of ischemic brain injury in any of the animals. Gross and histopathologic assessment of brain tissue also demonstrated no ischemic changes.


CONCLUSIONS
During RF ablation of lung tumors, microbubbles are detected in the carotid arteries in a small number of cases. These microbubbles are too few and too small to be detected by CT imaging of the brain and do not cause ischemic brain injury.
Ahrar
Kamran
K
Section of Interventional Radiology, The University of Texas, MD Anderson Cancer Center, Houston, TX 77030-4009, USA. kahrar@mdanderson.org
Stafford
R Jason
RJ
Tinkey
Peggy T
PT
Borne
Agatha T
AT
Stephens
L Clifton
LC
Wallace
Michael J
MJ
Wright
Kenneth C
KC
D000818:Animals; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging; D017115:Catheter Ablation; D038524:Diffusion Magnetic Resonance Imaging; D004285:Dogs; D017097:Electric Impedance; D020766:Intracranial Embolism / Q000175:diagnosis* / Q000473:pathology; D008175:Lung Neoplasms / Q000601:surgery*; D010865:Pilot Projects; D015641:Radiography, Interventional; D014057:Tomography, X-Ray Computed; D018616:Ultrasonography, Doppler, Duplex