Image guided tumour ablation

Abstract

Several different technologies have been employed for the local ablation of tissue by thermal techniques. At the present time the most widely favoured technique is radiofrequency ablation (RFA) but developments in other techniques, e.g. microwave may change this. In many countries RFA or percutaneous ethanol injection (PEI) are accepted therapies for patients with Childs Pugh Class A or B cirrhosis and early hepatocellular carcinoma (HCC). Results for RFA in large series of patients with liver metastases from colon cancer are very promising. Five-year survival rates of 26% from the time of first ablation and 30% from the diagnosis of liver metastases for patients with limited (<6, <5 cm) liver disease who are not surgical candidates compares well with post resection series where 5-year survival rates vary between 29% and 39% in operable candidates. Sufficient experience has now been gained in lung and renal ablation to show that these are minimally invasive techniques which can produce effective tumour destruction with a limited morbidity. More novel areas for ablation such as adrenal or pelvic recurrence are being explored.

Figure 1

(a) CT scan showing a single, water cooled electrode inserted percutaneously with the tip beyond the lung tumour prior to heating. Note invagination of the pleura. (b) CT scan the following day shows ground glass opacification that embraces the entire tumour—a good indicator of the ablation zone. There is no pneumothorax but there is surgical emphysema in the subcutaneous tissues over the left lateral chest wall. (c) CT scan 2 months later showing a wedge shaped opacification at the treatment site that is already starting to reduce in size.