Experimental methodologies for studying the effects of perfusion on high intensity focused ultrasound (HIFU)

The liver is a highly perfused organ. The temperature rise induced by HIFU proximal to blood vessels is likely to be lowered due to conductive cooling. Our aim was to develop novel biological and non-biological flow phantoms to investigate this phenomenon. The biological model employed freshly excised whole porcine livers perfused via the portal vein with Lactate Ringer solution. This model was chosen to best mimic human liver. The second phantom was non-biological, designed so that it could be used repeatedly even at high intensities over an extended period of time. It consisted of polyacrylamide gel enhanced with pulverized, vulcanized rubber. Very early results with both models have demonstrated a reduction in temperature rise with increasing flow rate. The phantoms developed in this study are likely to have wide ranging applications.