Contrast-Enhanced Endoscopic Ultrasonography (CE-EUS) Improves Visualization of Pancreatic Vasculature

Neovascularization in neoplasms may enable improved visualization with EUS if a contrast agent is used. Lipid microspheres are an established diagnostic tool for increasing contrast of vascular structures in echocardiography. Aim: To evaluate the potential utility of contrast enhanced EUS (CE-EUS) in the characterization of pancreatic lesions in a porcine model. Methods: 3 anesthesized 50kg pigs underwent EUS. For optimal visualization, the ultrasound mechanical index was decreased to 0.3. 2 mL of Perflutren lipid microspheres (5uL/kg) (Definity®) were administered by peripheral IV. The pancreas and peri-pancreatic vessels were re-imaged. To create an animal model of pancreatic microvascular disruption, 0.5 mL of 50% ethanol plus purified carbon particle solution (GI Spot®) was injected with an Olympus® 22g EUS-FNA needle into the body of the pancreas. 24–48 hours post ethanol-injection, the pancreas was re-evaluated. Standard and CE-EUS imaging of the pancreas were compared. Post-mortem examination was performed. Results: With conventional EUS, there was minimal color flow within the pancreatic parenchyma. Within 30 seconds of injection of microspheres, the microvasculature of the pancreas was well visualized with increased color flow. The microspheres were also well seen in the peri-pancreatic vessels. The mean duration CE-EUS visualization was 2.29 minutes. Standard EUS imaging showed a subtle 1cm hypoechoic region in the ethanol-treated area. Color and power doppler EUS of this region did not reveal any signal or blood flow. After microsphere injection, color Doppler EUS revealed marked contrast enhancement of normal pancreatic parenchyma from the alcohol-treated area, which on groß examination corresponded to the marked necrotic area. Conclusions: CE-EUS with microspheres improves EUS visualization of the pancreatic microvasculature and delineation of altered vascular perfusion.