Ultrasound-guided percutaneous microwave ablation of adrenal metastasis: Preliminary results

Purpose: To evaluate the feasibility, safety and therapeutic effects of ultrasound (US)-guided percutaneous microwave (MW) ablation in the treatment of adrenal metastasis. Materials and methods: From May 2006 to April 2008, five consecutive patients with pathologically proven unilateral adrenal metastases with a diameter of 2.3 to 4.5 cm were treated by US-guided percutaneous MW ablation. Four metastases were in the right side, one metastasis was in the left side. For each application, two cooled-shaft needle antennae were percutaneously inserted into the tumour under real-time US guidance. One thermocouple needle was inserted at the periphery of the tumour to monitor temperature in real-time during MW ablation. MW emission was ended when the entire tumour became hyperechoic and the temperature at the tumour border reached 54 degrees C for at least 3 min. Technical success was defined as loss of tumour enhancement on contrast-enhanced imagings. Results: All adrenal metastases were completely ablated after scheduled MW ablation sessions (mean, 1.2 sessions, range, 1 to 2 sessions). No major complications related to MW ablation occurred. In a median follow-up of 19 months (range 8 to 31 months), persistent absence of tumour enhancement was observed in the treated tumour in all patients. Conclusions: US-guided percutaneous MW ablation appears to be a safe and effective therapy in selected adrenal metastasis.