Table 1. Characteristics of different imaging modalities to diagnose extracranial carotid artery stenosis.

Diagnostic modality	Sensitivity†	Specificity†	Cost	Invasiveness	Radiation exposure	Contrast material	Intracranial vasculature	Disadvantages
Carotid duplex ultrasound	85–92%	77–89%	−	Non-invasive	No	No	No	Operator variability
								Poor differentiation of subtotal from total occlusion
								Overestimation of stenosis in the presence of contralateral occlusion
								Variability of diagnostic criteria
CT-angiography	68–84%	91–97%	+	Non-invasive	Yes	Yes	Yes	Susceptible to artifacts caused by calcified plaques
								Use of IV contrast
								Underestimation of stenosis
Time-of-flight MR-angiography	82–92%	76–97%	++	Non-invasive	No	No	Yes	Long acquisition time
								Susceptible to motion artifacts
								Overestimation of stenosis
								Contraindications for undergoing magnetic resonance
Contrast enhanced MR-angiography	88–97%	89–96%	++	Non-invasive	No	Yes (gadolinium)	Yes	Long acquisition time
								Low spatial resolution
								Risk for systemic fibrosis in patients with renal impairment
								Contraindications for undergoing magnetic resonance
Digital subtraction angiography	GS	GS	+++	Invasive	Yes	Yes	Yes	Risks associated to invasiveness of the procedure
								Use of IV contrast
								Risk of permanent neurological complications (~1%)
								Requires skilled operators and is done at specialized neurovascular centers

^†, sensitivity and specificity to detect 70–99% carotid stenosis (22). CT, computed tomography; GS, gold standard; MR, magnetic resonance.