CT angiography of the splanchnic vessels
Multi-slice CT angiography of the splanchnic vessels is a powerful minimally invasive technique for evaluation of the splanchnic vascular system.
The actual procedure will vary depending on institutional protocol/guidelines but below is a typical description 2, 4:
- patient receives 500-800 ml of negative oral contrast water to opacify the stomach and small bowels
- patient in supine position with arms up behind his head
- peripheral venous access (18-20G) in an antecubital vein
- a volume of 100–120 mL of iodinated contrast material is administered at a rate of 4-5 mL/sec.
- because both the mesenteric arterial and venous systems must be adequately evaluated, arterial and venous phases are obtained.
- arterial phase (obtained 25-30 seconds after contrast agent injection), images are obtained from above the level of the coeliac axis to the level of the common iliac arteries.
- portal phase (obtained 60–70 seconds after contrast agent injection), images in this phase are obtained from above the level of the diaphragm to below the level of the symphysis pubis.
Data acquisition and analysis
- images are analyzed on a dedicated workstation.
- two-dimensional (2D) multi-planar images, as well as rendering techniques such as maximum intensity projection (MIP), surface shaded displays (SSD) and volume rendering (VR)
- for 3D images of the splanchnic veins, coronal images of the portal vein and the proximal portion of SMV with its confluence to the splenic vein 1,3
CT angiograms are assessed for evidence of arterial stenosis or occlusion e.g.
- vessel occlusion is defined as complete obstruction of the lumen
- hemodynamically significant vessel stenosis is defined as a reduction in lumen diameter > 50%
- hemodynamically insignificant stenosis is defined as a reduction in lumen diameter < 50% 1
Axial CT images should be evaluated for secondary signs of ischemia e.g. bowel wall thickening, focal lack of bowel wall enhancement, bowel dilatation, mesenteric stranding, ascites, pneumatosis intestinalis, free superior mesenteric or portal venous gas, intraperitoneal air, solid organ infarction.
General CT contraindications include:
- previous severe reactions to contrast agents
- uncooperative patients
Mesenteric CT angiography has several advantages over conventional angiography as:
- it is a minimally invasive procedure
- low-cost examination
- takes less time
Arterial pathology: 5
- ischemia (Occlusion or stenosis)
- coeliac artery compression syndrome
- superior mesenteric artery syndrome
- segmental arterial mediolysis
- 1. Cademartiri F, Raaijmakers RH, Kuiper JW et-al. Multi-detector row CT angiography in patients with abdominal angina. Radiographics. 2004;24 (4): 969-84. doi:10.1148/rg.244035166 - Pubmed citation
- 2. Kirkpatrick ID, Kroeker MA, Greenberg HM. Biphasic CT with mesenteric CT angiography in the evaluation of acute mesenteric ischemia: initial experience. Radiology. 2003;229 (1): 91-8. doi:10.1148/radiol.2291020991 - Pubmed citation
- 3. Baert A, Passariello R. Multidetector-Row CT Angiography. Springer Science & Business Media. (2006) ISBN:3540269843. Read it at Google Books - Find it at Amazon
- 4. Andrea Laghi. CT Angiography of Splanchnic Vessels. 227-233. doi:10.1007/978-3-642-18834-3_22
- 5. Horton KM, Fishman EK. CT angiography of the mesenteric circulation. Radiol. Clin. North Am. 01;48 (48): 331-45, viii. doi:10.1016/j.rcl.2010.02.004 - Pubmed citation