The role of digital angiography in carotid artery disease

Angiography with intra-arterial injection of contrast agents is useful for investigation of extracranial carotid artery disease to clarify diagnostic problems not resolved by non-invasive tests. Digital angiography now employs thinner catheters and lower doses of contrast medium reducing the incidence of toxic reactions The incidence of drug intolerance is 0.8%, usually mild to moderate whereas the incidence of neurological complications during angiography of the carotidovertebral arteries is between 1.1% and 3.9%, according to different series, with permanent deficit occurring in 0.52% of patients. Digital angiography demonstrates the presence and distribution of calcifications within the atherosclerotic plaque. The high spatial resolution of digital angiography offers a detailed display of vessel wall changes in profile, including ulceration as well as an accurate measurement of stenosis, erosion and parietal ulceration which will aid in prognosis. The technique is especially useful in displaying the ''string sign'' of subocclusive lesions (>95-99%). An exact angiographic picture of the distal circulation is also necessary during surgical clamping and to detect other intracranial lesions. The fine alterations of nonatherosclerotic disease like dissections, fibrodysplasia and arteritis, are often located more distally and are thus better displayed by angiography than other less invasive techniques. Aneurysms of the extracranial carotid are better assessed with CT and ultrasound investigation. The role of angiography within the diagnostic protocol for extracranial carotid disease is currently the subject of debate. Angiography is no longer the gold standard among diagnostic imaging techniques but is still required to confirm doubtful or complex cases and remains the standard of practice in planning treatment protocols for epi-aortic arterial lesions.