The addition of contrast-enhanced ultrasound to monitor the extent of interstitial ablation has simplified this procedure. Newer agents such as SonoVue used with microbubble-specific software (CPS) allow continuous real-time scanning at low MIs so that, if residual perfused tumour is found, complete evaluation of the extent of tissue ablation can be carried out immediately after the procedure in the same treatment session. In the initial 18-month period after the introduction of these agents, partial necrosis occurred in 5.1% of treated lesions compared to the previous rate of 16.1%, and this improved to 3.8% in the following 2 years. The method is cost-effective because it reduces the need for repeated treatment sessions under general anaesthesia. The same method is helpful in treatment planning and follow-up.