How the Radiologist Must Reason for a Correct Diagnosis in Patients With Small Bowel Mural Thickening Studied by CT or MRI: A Pictorial Review.

Conditions that lead to small bowel mural thickening fall into a broad spectrum of diseases, including inflammatory, infectious, vascular or neoplastic. Computed tomography (CT) and Magnetic Resonance Imaging (MRI), especially CT-enterography and MR-enterography, permit evaluation of both entire small bowel and extraluminal structures. In CT/MR-enterography, the main prerequisite for the correct evaluation of small bowel is to obtain optimal intestinal distension. In fact, most errors are related to poor intestinal distension of the bowel which can lead to interpret as pathological a small bowel segment that is not very distended (false positive), or not to recognize presence of pathology in a collapsed segment (false negative). Once the examination has been performed, the images are analyzed in order to identify the presence of small bowel pathology. Pathology of the small bowel can manifest as endoluminal alteration and/or intestinal wall thickening. Once bowel wall thickening has been identified, the radiologist's first objective is trying to define benign or malignant nature of the alteration, using also patient's history and clinical features. Once the suspicion of benign or malignant pathology has been raised, the radiologist must try to formulate a diagnosis of nature. In this pictorial review we describe how the radiologist must reason for a correct diagnosis by answering a pattern of sequential questions in a patient with suspected small bowel disease studied by CT or MRI.