The purpose of this study is to evaluate whether contrast-enhanced endoscopic ultrasound (CE-EUS) improves the characterization of pancreas tumors and precancerous lesions, including cysts, in comparison to conventional endoscopic ultrasound (EUS). Participants will be patients who are undergoing an EUS for suspected pancreatic lesion. The study aims to learn how effective CE-EUS is in differentiating between normal and cancerous or precancerous tissue. Endoscopic ultrasound is a procedure performed with an endoscope that has an ultrasound probe at the end, where the pancreas is evaluated with the end of the endoscope located in the stomach and duodenum. In CE-EUS, the only additional step to conventional EUS is intravenous injection of contrast to evaluate lesions of interest. The goal is to determine whether the contrast agent will help to characterize pancreas lesions more favorably than conventional EUS. This study is designed to test the experimental use of Lumason and Definity. Lumason is approved by the U.S. Food and Drug Administration (FDA) for use in echocardiography and ultrasonography of the liver and urinary tract. Definity is approved by the FDA for use in routine echocardiography.