High intensity focused ultrasound, liver disease and bridging therapy.

High-intensity focused ultrasound (HIFU) is a non-invasive modality that uses an extracorporeal source of focused ultrasound energy. This technique was introduced by Lynn et al and is able to induce coagulative necrosis in selected tissues without damaging adjacent structures. Although HIFU has been studied for 50 years, recent technological developments now allow its use for tumours of the liver, prostate and other sites. In liver disease, HIFU has been used to treat unresectable, advanced stages of hepatocellular carcinoma (HCC) and liver metastases. Hepatocellular carcinoma is a serious health problem worldwide and is endemic in some areas because of its association with hepatitis B and C viruses (in 20% of cases). Liver transplantation (LT) has become one of the best treatments available because it removes both the tumour and the underlying liver disease such as cirrhosis (which is present in approximately 80% of cases). The prerequisite for long-term transplant success depends on tumour load and strict selection criteria regarding the size and number of tumour nodules. The need to obtain the optimal benefit from the limited number of organs available has prompted strict selection criteria limited to only those patients with early HCC who have a better long-term outcome after LT. The so-called "bridging therapy" has the aim of controlling disease burden for patients who are on the organ transplant waiting list. Amongst various treatment options, transarterial chemoembolisation and radiofrequency ablation are the most popular treatment choices. Recently, Cheung et al demonstrated that HIFU ablation is a safe and effective method for the treatment of HCC patients with advanced cirrhosis as a bridging therapy and that it reduced the dropout rate from the liver transplant waiting list. In this commentary, we discuss the current value of HIFU in the treatment of liver disease, including its value as a bridging therapy, and examine the potential advantages of other therapeutic strategies.