Ct scan of abdomen shows nothing besides colon, right?

Wrong. Ct scanning of the abdomen and pelvis shows the colon, yes, but not subtle mucosal lesions such as early cancer. It shows your internal organs such as the liver, spleen, kidneys and pancreas in great detail. It also shows your small intestinal and the numerous blood vessels. It can evaluate the connective tissue and fat to uncover inflammatory conditions or infections.