Ischemia (Acute Mesenteric Ischemia and Ischemic Colitis)

Abstract

Diagnosis of intestinal disease related to vascular disorders could represent a critical diagnostic challenge for the emergency radiologist. Terms such as “ischemia” and “infarction” of the intestine are often used erroneously as synonyms: however, whereas the ischemia could be a totally reversible event, the infarction corresponds to a tissue death with no chance for the tissue to heal. Both terms indicate as different degrees or stages of disease an injury caused by interruption of the blood supply to the intestinal tissue. It is possible to distinguish three main different conditions underlying an intestinal ischemic event: arterial blood supply deficiency mainly related to embolism or thrombosis; impaired venous drainage; decreased mesenteric blood flow or low-flow state. Acute mesenteric ischemia can be considered a real, true emergency because of the associated significant mortality rate, which can be extremely high. A prompt diagnosis of any intestinal ischemic disorder of the intestine is imperative. However, because most patients affected by bowel ischemia can present with nonspecific signs and symptoms, it could be difficult to diagnose intestinal ischemia or infarction. Diagnostic imaging and especially multidetector computed tomography (MDCT) could be of great help in the management of patients with acute abdomen related to suspected acute mesenteric ischemia. Knowledge of the pathophysiology of the intestine is essential in order to recognize findings related to pathologic changes of the intestine affected by vascular disorders in different stages of disease from different causes. In this chapter, MDCT findings of disorders from impaired venous drainage and from arterial blood flow insufficiency involving the small and the large intestine will be considered, considering also criteria for differential diagnosis.