[Incidental and "leave me alone" findings in the GI tract-part 1 : Intestinal lumen and intestinal wall].

CLINICAL PROBLEM: Due to the widespread use of computed tomography (CT) and magnetic resonance imaging (MRI) asymptomatic incidental findings of the gastrointestinal tract (GI) are increasingly being recognized. Incidental findings are frequently not part of the primary inquiry from referring physicians but it is obligatory to make a diagnosis and to stipulate the need for further clarification. RADIOLOGICAL STANDARD PROCEDURES: A multitude of incidental findings in the intestinal lumen, in the intestinal wall and in the adjacent mesenterium or subperitoneal space are shown in CT and MRI. METHODOLOGICAL INNOVATIONS AND ASSESSMENT: The first part of the two-part overview addresses the intestinal incidental findings in the lumen, such as coproliths, invaginations, mucoceles and chronic dilatations. In the intestinal wall, thickenings of neoplastic and nonneoplastic origins are discussed. Many of the findings can be classified as benign and as "leave me alone lesions" do not necessitate any further clarification but in contrast others need a definitive clarification. The most important incidental findings in the GI tract are systematically classified, illustrated and evaluated with respect to the clinical relevance, depending on the localization (e.g. stomach, small and large intestines).