CT angiography

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CTA of the hands (volume image)

The CT angiography (computed tomographic angiography, CTA) is an imaging technique in medicine, by means of which blood vessels can be represented in the body. The examination uses modern multi-line computed tomography . With the help of fast computers, the arteries or veins are segmented from the computed tomographic layer images and displayed in freely rotatable 3D representations. Modern so-called volume renderings are often colored (the raw images are always black and white). The vessels that can be represented are z. B. the arteries and veins in the brain, lungs, liver, spleen, kidneys and the vessels in the extremities. Fast scanners can also produce angiographic images of the coronary vessels on the beating heart.

The administration of approx. 80 to 100 ml x - ray contrast medium containing iodine is necessary, as in classical angiography , in order to contrast the blood vessels with the surrounding tissue. In contrast to X-ray angiography, however, the substance does not have to be injected directly into the vessels to be visualized, but only into an arm vein. The recording sequence is started manually or automatically with the first passage of the contrast agent bolus through the vascular region of interest and usually lasts only a few seconds.

CTA examinations are technically simpler and lower risk than X-ray angiography. However, the detail resolution of even the most modern CT scanners is even lower (typical voxel size: 0.5–1 mm³) than that of X-ray films, so that their use, especially on the heart and brain, has not yet become generally accepted. For therapeutic interventions on the investigated vessel ( balloon angioplasty , angioplasty , stenting , aneurysm - coiling ) the conventional angiography is still required.

The radiation exposure is relatively high with a CTA (up to 13  mSv ). Competing alternatives to CTA are duplex sonography and magnetic resonance imaging MR angiography .

Indications

Aortic aneurysm in the thorax and abdomen (DeBakey type III). Longitudinal layer from the CTA

Typical indications for CT angiography are:

Risks

The risks relate primarily to the use of iodinated contrast media :

Contraindications

literature

  • Mathias Prokop, Michael Galanski (Eds.): Spiral and Multislice Computed Tomography of the Body . Thieme, Stuttgart New York 2003, ISBN 3-13-116481-6 ( limited preview in the Google book search).
  • Roland C. Bittner, Khaled Hazim, Klaus Helmig: CT, EBT, MRT and angiography: radiological examination technology for MTAR and doctors . Urban & Fischer, Munich Jena 2003, ISBN 3-437-46000-5 ( limited preview in the Google book search).