Angio-computed tomography (synonyms: angio-CT; CT angiography; CT angio; CT vascular imaging) refers to a radiological examination procedure in which blood vessels are examined using computed tomography (CT). With this examination method, targeted images of the vessels of various body regions are possible, such as brain, thorax, heart (CT angiography of the heart, CT cardio, computed tomographic coronary angiography (CTCA; Cardiac computed tomography angiography, CCTA), abdomen (abdominal cavity), pelvis, extremities (arms or legs). The SCOT-HEART study showed that cardiac computed tomography angiography (CCTA) has a significant impact on the incidence of coronary artery disease (CAD) and its treatment. The 5-year incidence of the primary end point (cardiac death or nonfatal myocardial infarction) was significantly lower in the CTA group than in the standard group (2.3 vs. 3.9%; p = 0.004).
Indications (areas of application)
- Aneurysm – outpouching of blood vessels.
- Changes in the vessels or abnormalities [e.g., hemangiomas (vascular growths)]
- Vascular occlusions or stenoses (narrowing in the vessels).
- Representation of collateral circuits (bypass circuits).
- Suspected angina pectoris (synonyms: stenocardia, German: Brustenge, Herzschmerz, abbreviated AP); seizure-like pain in the chest) due to coronary artery disease (CAD; disease of the coronary arteries).
- Diagnosis of CHD
- Venous thrombosis, especially in the area of the brain or abdominal vessels, as well as the vessels of the extremities (arm or leg).
- Pulmonary embolism (occlusion of one or more pulmonary vessels).
The procedure
Computed tomography is one of the non-invasive, that is, not penetrating into the body, imaging X-ray diagnostic procedures. The body or the body part to be examined is imaged layer by layer with a rapidly rotating X-ray tube. A computer measures the attenuation of the X-rays as they pass through the body and uses this to determine a detailed image of the part of the body being examined.The principle of CT (computed tomography) is to show the differences in density of different tissues. For example, water has a different density than air or bone, which is expressed in different shades of gray. For even better differentiation of the types of tissue (in this case the vessels), the patient is administered a contrast medium containing iodine.The examination takes only a few minutes with the most modern equipment, i.e. the scanning process even takes only a few seconds, so that the patient can hold his breath during the examination process and movement artifacts become impossible.The examination takes place while the patient is lying down. The latest devices use the multislice method, i.e. several slices are taken at the same time. Modern examination devices use a 64-slice method, i.e. 64 slices are taken at the same time. This method can be compared to a Rettig, which is cut in a spiral shape. In this case, however, only one slice is involved, and in the method described above, 64 slices are produced one inside the other as a spiral and processed by the computer. Computer tomographs of the latest generation achieve a spatial resolution < 0.25 mm with a native temporal resolution < 70 msModern devices also work with a so-called low-dose technique, i.e. only 50% of the radiation is required to produce these precise images with a slice thickness of up to 0.4 mm. New reconstruction algorithms (reconstruction calculation methods) make this precision possible. The procedure used has the following advantages for the patient:
- Angio-CT is used especially in patients who wear a pacemaker and thus cannot be examined in MRI.
- Patients who are very restless and can not lie still for the long MRI examination procedure.
- Representation of collateral systems in vascular stenoses or occlusions in the 3D method (in 3-dimensional space, the vessels can be viewed from all sides in the examination area).
For imaging the vessels including the coronary arteries (arteries that surround the heart in a wreath shape and supply the heart muscle with blood), the administration of iodine-containing contrast medium is required.For computed tomographic coronary angiography (CCTA), see below Cardio-CT.
