Duplex ultrasound is an accurate screening test for ostial arterial lesions. A peak systolic velocity greater than 275 cm/s and an end-diastolic velocity greater than 45 cm/s seems to be highly specific for significant superior mesenteric artery (SMA) stenosis [14]. Moreover, patients with Behçet syndrome and GI involvement had increased flow in both the superior and inferior mesenteric arteries. These findings were not similar in patients with Behçet syndrome and no GI involvement. Altered pericolic fat may suggest presence of transmural necrosis [15, 16]. However, since the duplex scan has limitations, such as patients presenting with abdominal distention or intraperitoneal gas, and is operator-dependent, these findings may not be always reliable, and a second study with axial images of the abdomen is often necessary, in order to exclude other causes of pain and for analysis of the anatomy and planning of the procedure.

Endoscopy and colonoscopy are useful exams in cases where symptoms of upper or lower GI involvement are suspected, proceeding with biopsy if ulceration is present. Despite the few reports on the subject, the combination of the tests and radiographic findings facilitates the precise diagnosis of the vasculitis [17]. Ischemic enteritis may suggest Kawasaki’s disease, granulomatous enteritis can be present in Wegener granulomatosis, and mucosal edema and hemorrhage at the bowel may suggest systemic lupus erythematous or Churg-Strauss disease. During these procedures, the manipulation of the endoscopic device, the bowel insufflation, and biopsies must be performed with extreme caution and finesse, in order to prevent bowel perforation.

Contrast-enhanced computed tomography (CT) may provide useful information on inflammatory, neoplastic, and vascular diseases of the abdomen and have the advantage of assessment of emergent abdominal vascular conditions, ischemic bowel disease, and its complications. Bowel wall thickening, a “target sign,” an increased attenuation of mesenteric fat, increased or delayed enhancement in the bowel wall due to hyperemia, or frank bowel infarction or perforation with pneumatosis intestinalis, portal venous air, or pneumoperitoneum are suggestive of acute ischemia.

Arterial-phase CT scans and particularly CT angiography (CTA) are of great value in the evaluation of mesenteric arteries. Arterial wall thickening is a characteristic finding in patients with mesenteric vasculitis (Fig. 10.2). They help to identify site, level, and cause of bowel ischemia. In addition, venous phases may identify the mesenteric veins and the bowel wall itself, improving accuracy in the identification of bowel perforation and abscess [2, 8]. Limitations of the study are dye allergy and renal failure.

Angiography remains the “gold standard” test for diagnosis of peripheral vessel splanchnic disease, particularly visceral aneurysms in polyarteritis nodosa and arterial narrowing in Takayasu’s disease. Its role as confirmatory test and for planning revascularization diminished, in favor of the noninvasive modalities previously discussed. More frequently, angiography is obtained in conjunction with a planned endovascular intervention. Exceptions are patients with suboptimal imaging studies and those with extensive calcification, small vessels, or multiple prior stents causing metallic artifact.

Takayasu’s Arteritis (pulseless disease) is a large-sized vessel granulomatous vasculitis characterized by ocular disturbances and marked pulse weakening in the upper and lower extremities. It is related to fibrous thickening of the aortic arch with narrowing or obliteration of the ostia of the great vessels in the arch. TA involves the aortic arch, and in 32 % of the cases, it affects the rest of the aorta and its branches. Generalized symptoms and signs include malaise, fever, night sweats, arthralgia, and weight loss. GI symptoms are mainly nonspecific, such as anorexia, nausea, vomiting, and loss of weight, and start during the pulseless phase of the disease. GI morbidity is due to arterial stenosis; however, organ ischemia is rare. Chronic mesenteric ischemia has already been reported and is manifested similar to atherosclerotic presentation. Diagnosis is suspected by duplex scan and confirmed by arteriography or CTA. The findings consist in irregular thickening of the aortic wall with intimal wrinkling, stenosis, poststenotic dilatation, aneurysm formation, and occlusion with subsequent luxurious collateral circulation [2, 4, 8, 18].

Giant cell arteritis (GCA) is one of the most common vasculitides to present with occlusive mesenteric artery disease (Fig. 10.3). Giant cell arteritis is also known as temporal arteritis, cranial arteritis, or Horton disease. It most commonly involves large- and medium-sized arteries. Its original description affects branches of the external carotid artery and can lead to permanent blindness if not recognized and treated with corticosteroids. The name (giant cell arteritis) reflects the type of inflammatory cell involved and seen on a biopsy. The terms “giant cell arteritis” and “temporal arteritis” are sometimes used interchangeably, because of the frequent involvement of the temporal artery. However, it can involve other large vessels, such as the aorta (“giant cell aortitis”) and its branches.

Polyarteritis nodosa (PAN) is a fibrinoid necrotizing vasculitis that involves small- and medium-sized arteries. Multiple aneurysm formation (Fig. 10.1) is the characteristic finding of the disease and is present in 50–60 % of the patients [8]. The kidney is the most commonly involved organ (80–90 % of cases), followed by the gastrointestinal tract (50–70 %), liver (50–60 %), spleen (45 %), and pancreas (25–35 %). GI involvement increases mortality rates, due to the extensive destruction of the mesenteric arteries. The small intestine is the most commonly affected territory of the GI tract, followed by the mesentery and colon. Approximately two-thirds of patients have abdominal pain, nausea, and vomiting. Other gastrointestinal signs and symptoms include peritonitis, mesenteric infarction, acute cholecystitis, appendicitis, and duodenal ulcers. In association with organ damage due to ischemia and infarction, GI hemorrhage occurs in 6 % of cases, bowel perforation in 5 %, and bowel infarction in 1.4 % of the cases [1, 3, 4, 7, 8, 19, 20].