Non-occlusive mesenteric ischaemia (ECR 2014 Case of the Day)

Clinical History

A 50-year-old woman presented to the ER with sudden onset of diffuse abdominal pain, nausea, vomiting and haematochezia.
The laboratory results revealed leukocytosis and increased acute phase reactants. There was no history of drug use or other associated morbidity.

Imaging Findings

Two days upon admission, the patient developed increasing pain, gross distension, peritoneal signs and sepsis.
Abdominal CTA was performed and showed the following:
Extensive, but segmental, either small bowel wall thickening (1cm) or thinning (paper thin wall) with variable pattern of contrast enhancement (decreased or increased mostly layered pattern). The transition from normal to abnormal bowel is abrupt. A large amount of ascites was noted between the dilated bowel loops. There is stranding and thickening of the mesenteric fat (Fig. 1, 2, 3). Mucosal hyperaemia involving the hepatic flexure and the proximal transverse colon is present (Fig. 3).
CTA-MIP images showed diffuse narrowing of the superior mesenteric artery and its branches with poor filling of the vasa recta and interspersed areas of normal calibre vessels (Fig. 4). Follow up CTA 10 days post treatment showed improved vessel calibre (Fig. 5).

Discussion

Non-occlusive mesenteric ischaemia (NOMI) is a non-embolic, ischaemic condition of the intestinal tract that develops during a state of hypoperfusion and is associated with low superior mesenteric flow and mesenteric macrovascular and microvascular vasoconstriction without obstruction of the arterial flow [1-3].
Patients with NOMI are usually individuals aged over 50 years. To some extent, they share similar clinical presentation with all types of acute mesenteric ischaemia (AMI), usually with a more gradual onset of symptoms. Abdominal pain that is disproportionate to physical examination findings is the most common finding.
Although NOMI accounts for 20–30% of all AMI, it has more than 70% mortality.
Arteriography helps make the definitive diagnosis in most cases and demonstrates diffuse narrowing of the superior mesenteric artery, irregularities in the intestinal branches, spasm of the arcades, impaired filling of the intramural vessels, slow flow in the superior mesenteric artery and slow flow with increased reflux of contrast into the abdominal aorta during selective injection of the superior mesenteric artery [1, 2].
CT features of NOMI include:
• Non-specific findings of AMI : mesenteric and intestinal wall oedema, asymmetric bowel wall thickening and enhancement, mucosal enhancement, fluid accumulation in dilated small bowel loops and ascites [1, 3-5].
• Small size superior mesentery artery calibre with diffuse narrowing of its branches. The enhancements of arcade of mesenteric arteries and intramural vessels are severely impaired [1, 4, 6].

CTA allows the evaluation of SMA and its branches and can be an equivalent diagnostic modality to angiography for the diagnostic purpose of NOMI. At the same times it permits subsequent early initiation of therapy treatment with aggressive fluid resuscitation and vasodilators and monitoring of disease resolution.
Superior mesentery artery emboli-thrombosis/superior mesenteric vein thrombosis is associated with direct visualization of thrombus or embolus within mesenteric vessels, or abrupt change in vessel enhancement [7, 8].
Intestinal (angioneurotic) angioedema is either hereditary or seen as a rare complication of ACE inhibitor use. Swelling of the face and oropharynx is also present [7, 8].
Vasculitis (SLE, PN) usually presents with vessel wall abnormalities, multiple stenosis and/or aneurysms and may affect multiple organs. It may be indistinguishable on imaging alone, so additional specific laboratory tests are required [7, 8].
Chronic mesenteric ischaemia is a long-standing process with extensive calcified atherosclerotic disease [7, 8].
Crohn’s disease usually affects distal SB and presents as asymmetric and discontinuous wall thickening associated with proliferation of mesenteric fat, with no evidence of bowel wall thinning or decrease in vascularity enhancement [7, 8]

Differential Diagnosis List

Final Diagnosis

Non-occlusive mesenteric ischaemia

URL:	https://www.eurorad.org/case/11822
DOI:	10.1594/EURORAD/CASE.11822
ISSN:	1563-4086