Angiography works in the same way as conventional X-ray imaging using X-rays and, in addition to diagnostic procedures, also enables therapeutic interventions using minimally invasive techniques.
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- Philips Azurion Clarity IQ (2-plane angiography)
Similar to conventional radiography, X-rays are generated using an X-ray tube. Aperture systems are used to confine the radiation to the area of the body to be examined in order to minimise radiation exposure to areas of the body that are not to be examined. The X-rays are attenuated to a greater or lesser extent in the body by the different tissues according to their physical properties. Compact tissue such as bone or foreign materials such as prostheses, but also administered contrast agents, have a very high density and absorb a high proportion of radiation, while lung tissue, for example, only shows low absorption due to its high air content. On the opposite side, the rays are captured by a special detector and then converted into a video signal so that the doctor can view moving images on the screen.
Angiography is performed to visualise and assess diseases of the vessels (arteries and veins). This includes above all
- visualisation of vessels (e.g. neck and brain vessels, pelvic and leg vessels)
- Treatment of vascular stenoses caused by vascular calcifications or soft wall deposits (balloon dilatation, stent placement, lysis of thrombi)
- Protrusions of vessels (aneurysms)
- Elimination of vascular dilatations (so-called aneurysms) and vascular malformations by means of coiling, Further information
- Vascular injuries
- Percutaneous transhepatic cholangiography (PTC) and insertion of drains (PTCD) or stents
- Intra-arterial selective chemoembolisation of liver tumours
In addition, vascular images are sometimes required before operations to assess the course of the operation.
In contrast to other imaging procedures for vascular visualisation (computer tomography or magnetic resonance imaging), small interventions can also be carried out in the same examination. These include above all the widening of vascular constrictions using a balloon catheter or a stent, but also the closure of bleeding vessels with small metal coils or adhesive liquids and the elimination of aneurysms.
In some cases, tumours can also be selectively treated directly on site with therapeutic medication or the supplying vessels can be closed before an operation.
To visualise the vessels, they must be punctured (pierced). In order to minimise the risk of bleeding from the puncture site after the examination, the blood coagulation system must be intact. It is therefore necessary to have current blood values for coagulation before the examination and, if necessary, to discontinue certain anticoagulant medication beforehand. Therefore, please inform your doctor or the radiologist before the examination if you have any known blood clotting disorders or are taking anticoagulant medication.
Iodine-containing contrast medium is used to visualise the vessels, which is usually injected via the artery or a vein. The following questions should therefore be clarified in advance:
- Is kidney function normal?
As most of the contrast medium is excreted via the kidneys, a current blood value (creatinine, GFR) should be available if kidney function is known to be impaired. If necessary, the kidney function must be improved with medication before the examination.
- Is there hyperthyroidism?
As the contrast medium contains iodine, hyperthyroidism could be aggravated. If thyroid dysfunction is known, current thyroid parameters should be determined in advance (TSH, fT3, fT4). It may be necessary to block the thyroid function.
- Is there a known allergy to iodine-containing contrast media?
If allergic reactions are known, anti-allergic medication must be administered in advance.
You should therefore inform your attending physician or the radiologist before the examination of any known pre-existing conditions so that appropriate measures can be taken if necessary.
As a rule, the large artery or vein in the groin is chosen as the access to the vessels. Alternatively, other access points are available in the crook of the elbow or at the wrist. After local anaesthesia, catheters are advanced into the region to be examined with the aid of guidewires and from there contrast agents are injected or vessel-opening (stent, balloon, thrombus-dissolving medication, etc.) or vessel-closing measures are initiated. These procedures are controlled on the monitor under fluoroscopy.
At the end of the examination, a pressure bandage is applied to close the small hole in the vessel wall at the site of the puncture or a closure system is inserted. Depending on the type of closure, a shorter (2 hours) or longer (up to 24 hours) lying time is required after the examination to prevent post-operative bleeding.
General complications can occur in connection with the administration of the iodine-containing contrast agent, where allergic reactions, damage to the kidneys or a worsening of pre-existing hyperthyroidism can occur in rare cases.
Further risks arise from puncturing the blood vessels or manipulating the vessels using wires and catheters. Possible complications include bruising (haematomas), vessel wall injuries (tears, bulging), fistula formation or the spread of vessel wall deposits.
