Evidence-based On-call

Stroke

Investigations

For patients willing to have carotid endarterectomy, consider carotid ultrasound ^a

or MR angiography ^a

followed by angiography if indicated ^a

Why?

Magnetic resonance angiography or duplex ultrasonography alone cannot safely diagnose or exclude significant stenosis

Patient	Target Disorder and Reference Standard	Diagnostic Test	LR+ (95% CI)	Post-test Probability	LR- (95% CI)	Post-test Probability
suspected carotid artery disease ^a (pre-test probability: 12%)	>70% carotid artery stenosis (angiography)	magnetic resonance angiography	24 (7.6 to 75)	77%	0.17 (0.048 to 0.61)	2%
suspected carotid artery disease ^a (pre-test probability: 33%)		Duplex ultrasonography	4.6 (2.4 to 8.8)	68%	0.23 (0.09 to 0.57)	10%
		Doppler ultrasonography	6.0	75%	0.19	9%
suspected carotid artery disease (pre-test probability: 50%)	> 50% carotid artery stenosis (angiography)	Duplex ultrasonography	5.7	86%	0.18	16%