September Spotlight — Radiology: Microwave ablation of liver lesions


Submitted by Vikram Dravid, MD, FACR, Interventional Radiology


Diffuse neoplastic involvement of the liver has various treatment options including chemotherapy and interventional procedures such as chemoembolization and Y90 embolization. More focal disease may be better addressed using percutaneous image guided ablation.


Thermal ablation has been utilized to treat cancers of the liver, lung, kidney and bone. Radiofrequency ablation, Microwave ablation and Cryoablation are techniques utilizing localized exposure of tumors to extreme temperatures to cause cell death. Temperatures exceeding 60 degrees centigrade are known to cause instantaneous cell death. Tumors less than 3 cm in size are best suited for the percutaneous approach although larger tumors have been successfully treated.


Radiofrequency ablation is currently the most popular modality and relies on electrical conduction through tissue causing resistive heating particularly for ablation of the peripheral tumor areas. RF ablation may require deployment of multiple prongs or use of multiple electrodes increasing the invasiveness and potential morbidity of a procedure. Proximity to large vessels diminishes the effectiveness of RF heating.


Microwave ablation uses dielectric heating and is accomplished by applying an alternating electromagnetic field to an imperfect dielectric material. [tissue]. The major difference between microwave and RF heating is that microwave heating occurs in a volume around the applicator while RF heating is limited to areas of high current density. Microwaves offer the same benefits as RF energy for thermal ablation in the liver but perform better in ablating tissue adjacent to large vessels and creates larger zones of ablation in high perfusion areas. Thus microwave technology can provide precise, predictable, spherical burns in a short period of time with minimal patient discomfort using a single 13g applicator.


The therapy can be potentially curative, particularly with single small lesions. It is performed in an outpatient setting. Patients are discharged within a few hours following completion of the procedure with minimal discomfort.


Interventional Radiology at Mainline Health proudly offers Microwave ablation. Please contact the interventional radiologist at your campus. My contact information is Vikram Dravid, MD, FACR / 484-337-4113


Case illustration:

57 year old male with metastatic gastric carcinoma. Following a complete course of chemotherapy two focal metastatic lesions in the liver decreased in size but persisted. CT guided microwave ablation was performed.


CT scan of the abdomen showing metastatic lesions in the right [1] and left [2] lobes.


Both lesions decreased in size following systemic chemotherapy.



CT guided microwave ablation of lesion 1


CT guided microwave ablation of lesion 2.


No evidence of residual or recurrent tumor 3 months post ablation – lesion 1


And lesion 2.



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