Figure 5 shows representative CT images of a pancreatic tumor before and after HIFU therapy. Figure 5 Contrast enhanced-CT

scan of a 52-year-old male demonstrating a tumor in the body of the pancreas (A) prior to high intensity focused ultrasound therapy; (B) with evidence of ablation and necrosis following high intensity focused ultrasound therapy. Reproduced … In a small study from Europe (55) 6 patients with pancreatic tumors in difficult locations were treated with HIFU, the difficult location being defined as a tumor adjacent to major blood vessels, gallbladder and bile ducts, bowel, Inhibitors,research,lifescience,medical or stomach. This study was performed under general anesthesia, after 3-days of bowel preparation to avoid the presence of bowel gas in the Onalespib clinical trial acoustic pathway. Symptoms were clearly palliated within 24 hours after treatment in all patients, and the amylase level showed no statistically significant elevation over baseline 3 days after treatment. According to PET/CT and MDCT scans, the Inhibitors,research,lifescience,medical entire Inhibitors,research,lifescience,medical tumor volume was successfully ablated in all cases. A major complication – portal vein thrombosis – was observed in one patient, who was hospitalized for 7 days. The results

of the studies are summarized in Table 1, and, as seen, pain relief was achieved consistently in all studies. However, no randomized, controlled trials have been performed to date to confirm these findings or to determine if HIFU can improve overall survival by inducing local tumor response. Table 1 Clinical studies of HIFU for palliative therapy of pancreatic Inhibitors,research,lifescience,medical cancer (Adapted from Jang HJ et al. (11)) Challenges and future directions The major factors that complicate HIFU ablation of pancreatic

tumors are the presence of bowel gas, respiratory Inhibitors,research,lifescience,medical motion and the absence of ultrasound-based temperature monitoring methods. Bowel gas may obstruct the acoustic window for transmission of HIFU energy, which may lead to not only incomplete ablation Adenosine of the target, but also thermal damage to the bowel or colon due to rapid heat deposition at the gas-tissue interface. Therefore, it is critical to evacuate the gas in the stomach and colon, which can be achieved by having the patient fast the night before treatment. Applying slight abdominal pressure to the target area also helps to displace gas and clear the acoustic window. Respiratory motion of the tumor during the treatment leads to redistribution of acoustic energy over the area larger than the focal region and may result in incomplete treatment of the target and damage to adjacent tissues. Respiratory motion tracking techniques that would allow for rapid focal adjustment in sync with the target position are currently in development (57).