Acute mesenteric ischaemia: a pictorial review

Acute mesenteric ischaemia (AMI) is an uncommon cause of acute hospital admission with high mortality rates (50-90%) that requires early diagnosis and treatment. With the increase in average life expectancy, AMI represents one of the most threatening abdominal conditions in elderly patients. Untreated, AMI will cause mesenteric infarction, intestinal necrosis, an overwhelming inflammatory response and death. Early intervention can reverse this process leading to a full recovery, but the diagnosis of AMI is difficult. The failure to recognise AMI before intestinal necrosis has developed is responsible for the high mortality of the disease. Unfortunately, common CT findings in bowel ischaemia are not specific. Therefore, it is often a combination of nonspecific clinical, laboratory and radiological findings that helps most in the correct interpretation of CT findings. The purpose of this article is to provide an overview of the anatomy, physiology of mesenteric perfusion and discussions of causes, pathogenesis and CT findings in various types of acute bowel ischaemia. Familiarity with various imaging features of mesenteric injury is essential to make a timely diagnosis that will lead to improved patient outcomes. TEACHING POINTS: • AMI is a potentially life-threatening disorder whose prognosis depends on early recognition, accurate diagnosis and timely intervention. • Arterial inflow occlusion due to thrombosis or embolisation is the most common cause of AMI. • Four aetiological types of AMI have been associated with different characteristics and risk factors (EAMI, TAMI, VAMI and NOMI). • Physical examination and laboratory findings are not sensitive or specific for diagnosing AMI; therefore, MDCT is still the first-line imaging method in suspected AMI. • Although a number of scoring systems for prognosis have been proposed, these have not been validated in large-scale studies.