This is a nice ultrasound image of colitis in a child. Observe the grossly thickened wall of the caecum and the associated mesenteric lymph node enlargement. This child also had other findings including round worm infestation and appendicitis.
See: http://www.ultrasound-images.com/colon.htm (for full case and more ultrasound images).
Image courtesy of Dr. Gunjan Puri, Surat, India.