Can contrast harmonic endoscopic ultrasonography replace endoscopic ultrasonography-guided fine-needle aspiration in patients with solid pancreatic lesions? An American perspective

Contrast harmonic endoscopic ultrasonography (CH-EUS) is a novel form of endoscopic ultrasonography (EUS) that utilizes intravenous contrast agents to characterize the vasculature inside an organ of interest with a broadband transducer that can detect harmonic signals.[1,2] These contrast agents initially played a major role in echocardiography, enhancing the power of ultrasonography to image cardiac chambers and the nearby large blood vessels.[3] They have been since utilized with EUS to aid clinicians in differentiating between benign and malignant lesions, in determining the depth of esophageal, gastric, and gallbladder cancer invasion, and in imaging the portal venous system and varices.[2] Contrast agents are especially important in tumor imaging because tumor angiogenesis usually significantly alters the vasculature within the malignant lesion. The intravenous contrast agents are typically administered via an intravenous bolus injection of gaseous microbubbles that do not leave the vascular system and reflect the ultrasound waves. The contrast can also be injected as a continuous infusion, which can alter the appearance of vasculature on CH-EUS due to the difference in intravascular density of the contrast material.