Utility of MDCT in emergency setting of acute mesenteric ischemia

Abstract

A cute mesenteric ischemia (AMI), which is a consequence of impaired blood flow to the gastrointestinal tract, is a life-threatening entity with an estimated mortality rate ranging between 60% and 90% (1-3). Among major etiologies of AMI are superior mesenteric artery (SMA) embolus, SMA thrombus, superior mesenteric vein (SMV) thrombosis and non-occlusive vasoconstriction (1). Minor causes of AMI include aortic dissection, intestinal volvulus, internal hernia, and adhesion band related extrinsic compression of the mesenteric vessels (4, 5). Although it is relatively rare (around 1% of all acute abdomen referrals), prompt diagnosis and treatment of AMI is important since early management of this clinical entity increases survival (6). Diagnosis of acute mesenteric ischemiaDiagnosis of AMI requires strong suspicion since the clinical features are usually non-specific such as abdominal pain, nausea, vomiting, or even diarrhea (7). Until late 1960s, surgical exploration or autopsy was used for diagnosis; then imaging modalities came into use as new diagnostic tools (8). Plain radiography and ultrasound are generally initial modalities used in patients presenting with acute abdomen in an emergency room, but their role is limited in the demonstration of primary and secondary signs of AMI. On plain radiographs, dilated bowel segments with air-fluid levels, pneumatosis and portal venous gas can be seen, whereas ultrasound can demonstrate mesenteric thrombus via Doppler mode but the presence of extensive gas within bowel segments and incompliance of patients may limit the accuracy of this imaging modality (6,8,9).Digital subtraction angiography (DSA) has been regarded as the gold standard imaging method in the setting of AMI. It not only enables direct visualization of the mesenteric vasculature but also provides prompt endovascular intervention opportunity (10). On the other hand, DSA is invasive, expensive, needs experience and, unfortunately, not readily available (10).Computed tomography (CT) became a powerful tool in the management of AMI with the introduction of multidetector technology, as it provides direct visualization of the mesenteric vasculature, intestines and mesentery (7). With its high spatial resolution and volumetric 3 dimensional reconstructions, multidetector CT angiography (MDCTA) allows direct non-invasive visualization of the etiology of AMI and its insults on the intestines, and associated findings/pathologies through a great anatomical detail window (6, 11).Magnetic resonance (MR) angiography is another non-invasive tool for the detection of AMI by determining mesenteric flow. It can be used as a second choice in children but its power is by far limited in the demonstration of calcified plaques (12, 13). ABDOMINAL IMAGING PICTORIAL ESSAY Utility of multidetector CT in an emergency setting in acute mesenteric ischemiaBarış Türkbey, Erhan Akpınar, Barbaros Çil, Muşturay Karçaaltıncaba, Okan Akhan ABSTRACT Prompt diagnosis of acute mesenteric ischemia is a dilemma which is unfortunately generally m...

Acute mesenteric ischemia due to superior mesenteric artery embolism in a patient with permanent atrial fibrillation

“…(9) Concordantly with CT angiography findings, enhanced collaterals detected with catheter angiography may indicate chronic occlusion of the SMA. (7,9) However, in some cases of AMI rapid establishment of a collateral vessel prevents development of bowel necrosis. Disadvantages of traditional angiography are its limited availability and potential renal toxicity as well as its monetary and time constraints.…”

“…(7) More recently, multidetector CT and MR angiography have replaced plain film and standard CT use, and become the cornerstones of AMI diagnosis. (7,8) Multidetector CT angiography represents a fast and accurate investigation tool for the diagnosis of AMI. In most cases it can be used as the sole diagnostic procedure.…”

Akut Abdomen

“…Venöz trombozda superiyor mezenterik vende ya da dallarında trombüs ile uyumlu dolum defekti vardır. Pnömatozis intestinalis, portal sistemde hava, perforasyona bağlı serbest peritoneal hava ve serbest peritoneal sıvı ileri düzeyde iskemide etiyolojiden bağımsız olarak görülebilir (Şekil 10A, B) [48,49].…”

“…Özellikle arteryel oklüzyonda mortalite oranları tedaviye rağmen %60-80 düzeylerine ulaşabildiği için en ufak şüphede hızlı ve uygun görüntüleme yapılması ve görüntülemenin değerlendirilmesinde arteryel ve venöz yapılara dikkat edilmesi önemlidir [49].…”

Limited utility of MRA for acute bowel ischemia after portal venous phase CT

“…AMI entails vascular compromise of the small bowel and encompasses a variety of etiologies, including mesenteric arterial embolic or thrombotic occlusion, mesenteric venous thrombosis, and nonocclusive mesenteric ischemia [4]. Acute arterial thromboembolism accounts for nearly two-third of cases [5], compared with smaller proportions for venous thrombosis (10%) and nonocclusive ischemia (25%) [6]. Patients with AMI present with a variety of often nonspecific complaints, including sudden or gradual onset of abdominal pain, nausea and vomiting, diarrhea, or bloody stools [7].…”