Evaluation of the Feasibility, Safety, and Accuracy of an Intraoperative High-intensity Focused Ultrasound Device for Treating Liver Metastases

Today, the only potentially curative option in patients with colorectal liver metastases is surgery. However, liver resection is feasible in less than 20% of patients. Surgery has been widely used in association with radiofrequency, cryotherapy, or microwaves to expand the number of treatments performed with a curative intent. Nevertheless, several limitations have been documented when using these techniques (i.e., a traumatic puncture of the parenchyma, a limited size of lesions, and an inability to monitor the treatment in real-time).High-intensity focused ultrasound (HIFU) technology can achieve precise ablations of biological tissues without incisions or radiation. Current HIFU devices are based on an extracorporeal approach with limited access to the liver. We have developed a HIFU device designed for intraoperative use. The use of a toroidal transducer enables an ablation rate (10 cm(3).min(-1)) higher than any other treatment and is independent of perfusion. The feasibility, safety, and accuracy of intraoperative HIFU ablation were evaluated during an ablate-and-resect prospective study. This clinical phase I and Ila study was performed in patients undergoing hepatectomy for liver metastases. The HIFU treatment was performed on healthy tissue scheduled for resection.Liver metastases measuring less than 20 mm will be targeted during phase IIb (currently ongoing). This set-up allows the real-time evaluation of HIFU ablation while protecting participating patients from any adverse effects related to this new technique. Fifteen patients were included in phase I-Ila and 30 HIFU ablations were safely created within 40 s and with a precision of 1-2 mm. The average dimensions of the HIFU ablations were 27.5 x 21.0 mm(2), corresponding to a volume of approximately 7.5 cm(3). The aim of the ongoing phase IIb is to ablate metastases of less than 20 mm in diameter with a 5 mm margin.