Multidetector CT Angiography for Acute Gastrointestinal Bleeding: Technique and Findings

Abstract

Acute gastrointestinal bleeding is a common reason for emergency department admissions and an important cause of morbidity and mortality. Factors that complicate its clinical management include patient debility due to comorbidities; intermittence of hemorrhage; and multiple sites of simultaneous bleeding. Its management, therefore, must be multidisciplinary and include emergency physicians, gastroenterologists, and surgeons, as well as radiologists for diagnostic imaging and interventional therapy. Upper gastrointestinal tract bleeding is usually managed endoscopically, with radiologic intervention reserved as an alternative to be used if endoscopic therapy fails. Endoscopy is often less successful in the management of acute lower gastrointestinal tract bleeding, where colonoscopy may be more effective. The merits of performing bowel cleansing before colonoscopy in such cases might be offset by the resultant increase in response time and should be weighed carefully against the deficits in visualization and diagnostic accuracy that would result from performing colonoscopy without bowel preparation. In recent years, multidetector computed tomographic (CT) angiography has gained acceptance as a first-line option for the diagnosis and management of lower gastrointestinal tract bleeding. In selected cases of upper gastrointestinal tract bleeding, CT angiography also provides accurate information about the presence or absence of active bleeding, its source, and its cause. This information helps shorten the total diagnostic time and minimizes or eliminates the need for more expensive and more invasive procedures.

Endoscopic and angiographic management of lower gastrointestinal bleeding: Review of the published literature

“…Some series even report sensitivities of 100% and specificities of 96%. 20 Furthermore, CTA is able to isolate the site of bleeding and permit the investigator to express differential diagnoses. 21 In a meta-analysis of 124 patients with gastrointestinal bleeding who underwent CTA, extravasations of contrast medium were seen in 74 patients (60%).…”

Clinical significance and MDCT angiographic presentation of the mesenteric collateral circulation of the colon

“…Occlusion of mesenteric arteries is characterized by slow progression and non-specific clinical features, unlike venous occlusion (34). MDCTA represents the gold standard in the diagnosis of this condition (35). Secondary signs indicating acute mesenteric occlusion are: wall thinning of the intestine, slow recovery and free fluid infusion (36).…”

“…The arterial phase begins when automatic measurements achieve a density of 150 Hounsfield Units (HU) in the proximal part of the abdominal aorta. The port phase starts after 40-60 seconds, or 70-90 seconds from the beginning of intravenous contrast administration (35,46). In 3D imaging of abdominal structures and/or blood vessels, two methods are used: Maximum intensity projection (MIP) imaging and volume rendering (VR).…”

“…VR uses a complex software algorithm and allows reproducing structures of different densities in 3D in a more effective way than the MIP. The application of both methods for 3D visualisation of blood vessels involves the use of special workstations for post-processing of examinations (35,(45)(46).…”

iPad-based primary 2D reading of CT angiography examinations of patients with suspected acute gastrointestinal bleeding: preliminary experience

“…The feasibility of the endovascular treatment is established based on the patient's clinical parameters and vascular anatomy and should be assessed by dedicated vascular interventional radiologists owing to its invasiveness and its potential complications. [8][9][10][11][12][13][14] However, such specialists are not always physically available in every hospital unit on a 24/7 basis, making prompt remote consultation of CTA examinations by a vascular interventional radiologist a vital issue. In this scenario, remote tablet-based preliminary 2D reading of CTA studies of patients with suspected ANVGIB by on-call interventional radiologists could be a time-saving and costeffective solution for the management of such patients.…”