In conventional angiography, the blood vessels are imaged after opacification by contrast medium. In neuroradiology, arteries and veins which supply the brain, skull and spinal cord are examined. After local anaesthesia, the femoral artery is punctured in the groin and under x-ray control, a thin (usual diameter: 1.7 mm) catheter is advanced up into the carotid and/or vertebral arteries. This procedure is painless, but during the injection of contrast medium, the patient experiences a feeling of warmth in the body part supplied by the injected artery.
The angiographic images are postprocessed immediately after exposure in a way that bones and other structures of high radiodensity masking the blood vessels are electronically subtracted from the angiograms (digital subtraction angiography). By a rotational technique, three-dimensional images can be computed which are used for planning of endovascular interventions.
Being an interventional procedure, conventional angiography of the brain-supplying arteries carries a certain risk of neurologic complications as pareses or disturbances of vision or speech which even in experienced hands and with application of modern equipment and contrast media is in the range of 0.5%. Because of this and due to the rapid improvement of MRT- and CT-based angiographic techniques, indications for diagnostic angiographies are becoming rare. Nowadays, conventional angiography is mainly carried out in the context of an endovascular intervention as embolizations of vascular malformations (aneurysms, angiomas) or recanalization of a stenosed or occluded artery.