Computed tomography angiography

The CT angiography ( computed tomographic angiography, CTA) is an imaging method in medicine, which helps blood vessels can be displayed in the body. The study makes use of modern multi-slice computed tomography. The arteries or veins are segmented and displayed in a freely rotatable 3D graphs using fast computer from the CT slice images. Modern so-called volume renderings are often colored ( the raw images are always black and white). The displayable vessels are here, for example, the arteries and veins in the brain, lung, liver, spleen, kidneys, and vessels in the extremities. Fast scanners can produce on a beating heart and angiographic images of coronary vessels.

The administration of 80 to 100 ml of iodine-containing x-ray contrast agent is required as in the conventional angiography, to contrast with the blood vessels relative to the surrounding tissue. However, the substance must, in contrast to X-ray angiography not be injected directly into the displayed vessels, but only in an arm vein. The shooting sequence is started manually or automatically by the region of interest vessel during the first pass of the contrast bolus and usually lasts only a few seconds.

CTA studies are technically easier and less risky than X-ray angiographies. However, the detail resolution even the most modern CT scanners is even lower ( typical voxel size: 0.5 - 1 mm) than that of the X-ray films so that their use has specifically not generally enforced at the heart and brain. Also for therapeutic interventions in the studied vessel (balloon, angioplasty, stenting, aneurysm coiling), conventional angiography is still required.

The radiation exposure is at a CTA relatively high (up to 13 mSv ). Competing alternatives to the CTA, duplex ultrasound and magnetic resonance imaging, the MR angiography.

Indications

Typical indications for CT angiography are:

  • Suspected pulmonary embolism
  • Suspected aneurysm in the head, in the aorta or other arteries
  • Constrictions of the extremities arteries ( arterial disease)
  • Narrowing of the arteries supplying the brain
  • Narrowing of the renal artery ( renal artery stenosis)

Risks

The risks are mainly related to the use of iodinated contrast media:

  • Allergic reactions
  • Deterioration of renal function in pre-existing renal insufficiency or diabetes mellitus
  • Thyrotoxic crisis with pre-existing thyroid autonomy

Contraindications

  • In pregnancy are the benefits and risks - even by the use of ionizing radiation - carefully weigh against each other
  • Renal failure
  • Plasmacytoma
  • Known allergy to iodinated contrast media
  • Hyperthyroidism
Medical imaging Guglielmi Detachable Coil Contrast medium
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