A dual-frequency endoscopic transducer for imaging vascular invasion in pancreatic cancer

Pancreatic adenocarcinoma is among the most deadly of cancers, with surgery being typically the only curative option. Tumor resectability is typically determined via endoscopic ultrasound imaging, however, many patients who may be eligible for resection are not offered surgery due to the difficulty in determining vascular or lymphatic invasion. Contrast-enhanced ultrasound imaging may address this problem. We describe the development of a single element dual-frequency transducer for rotational endoscopic imaging designed to operate at 4/20 MHz to image microbubble superharmonics. The ability of the developed transducer to image in a tissue mimicking phantom at depths from 1.0 cm (CTR = 21.6 dB) to 2.5 cm (CTR = 11.4 dB) is demonstrated. The completed 4-Fr transducer is also capable of imaging microbubbles in a 200 µm-diameter tube through the wall of a ∼1 cm-diameter porcine artery, suggesting such a device may be suitable for direct visualization of small vessels from within the lumen of larger vessels such as the portal vein.