Endoscopy and radiological imaging are complementary. However the gastro-intestinal tract is routinely being imaged in CT and ultrasound, often performed for other indications. When an abnormality is discovered, several questions have to be addressed. Is the lesion due to a bowel abnormality? When bowel wall thickening is present, is it due to poor opacification or is it due to inflammation or tumor? Circumferential symmetrical thickening is more in favor of an inflammatory lesion, while focal asymmetrical thickening is more in favor of a neoplastic lesion. Inflammatory and lymphomatous lesion can have similar appearances. Guidelines to aid in diagnostic interpretation of gastrointestinal lesions are discussed, including features of appendicitis and obstruction.