b. Recording of CE-EUS images - procedure performed exclusively for research purposes. Duration 3-4 minutes i. The endoscopist will perform an additional reading with the contrast and record a 3-4 minute segment for review later using the harmonic mode of the ultrasound probe at a mechanical index of 0.3. The mechanical index may need to be be optimized, however a previous study found 0.3 to be optimal. Aspects that will be analyzed later are sequence of filling (central vs peripheral), timing (arterial [0-30s], venous [60-180s], post-venous/equilibrium phase [>180s]), pattern of perfusion (homogenous vs heterogenous, and with or without defect) and degree of venous washout. After the experimental portion of the procedure the endoscopist will fill out a form (see attached) to record their impressions of the characteristics of the tumor with contrast. The images will be saved for further comparison with the CT scan and the pathology results at a later time.