At luminal evaluation of the large intestine., any masslike protrusionthat is covered by normal mucosa., whether the underlying process isintramural or extramural in origin, may be reported as a submucosallesion. The full characterization of submucosal lesions may be difficultwith optical colonoscopy alone., and endoscopic biopsy is often nondiagnostic. Cross-sectional radiologic imaging studies allow evaluation ofthe entire thickness of the bowel wall and surrounding tissues and oftenprovide additional information with regard to lesion origin, internalcomposition., and extent of disease. Likewise., it may be difficult to distinguish submucosal lesions from mucosal polyps on radiologic images,and optical colonoscopy may provide complementary informationabout superficial submucosal soft-tissue lesions that are detected atcomputed tomographic (CT) colonography or barium imaging. Depending on the specific clinical situation, colonoscopy, CT colonography, transrectal ultrasonography, and magnetic resonance imaging allmay play an important role in the diagnostic evaluation of submucosallesions of the large intestine. It is important that radiologists be familiarwith the multimodality imaging appearances of such entities so thatneoplasms-especially those that are malignant-can be accuratelyidentified and characterized and effectively managed.