Computed tomographic (CT) scanning and magnetic resonance imaging (MRI) are useful for evaluating the question of cerebral infarction which may result from carotid artery stenosis. Infarctions related to internal carotid artery stenosis may be deep, subcortical, or cortical. However, carotid stenosis may exist in the absence of infarction on MRI and CT.
The definition of asymptomatic or symptomatic carotid artery stenosis is based upon the history and physical examination, depending upon whether or not there are symptoms or signs of carotid territory ischemia. In the large clinical trials addressing the management of carotid artery stenosis, the detection of "silent" infarcts on CT or MRI did not qualify the stenosis as symptomatic. In clinical practice, however, radiographic evidence of ischemia in the territory of a stenotic internal carotid artery may affect management.
Four diagnostic modalities are used to directly image the internal carotid artery:
- Cerebral angiography
- Carotid duplex ultrasound
- Magnetic resonance angiography
- Computed tomographic angiography
This topic will review the clinical use of these different techniques and their unique advantages and disadvantages. In addition, we will review the different methods of measuring the degree of carotid stenosis used with angiography. Other aspects of carotid disease are discussed separately. (See "Pathophysiology of symptoms from carotid atherosclerosis" and "Management of symptomatic carotid atherosclerotic disease" and "Management of asymptomatic carotid atherosclerotic disease".)