False-negative contrast MRA in the setting of carotid artery dissection

A case of false-negative contrast magnetic resonance angiography (MRA) in the setting of significant carotid stenosis caused by a carotid arterial intimal dissection is described. If arterial dissection is suspected but contrast MRA is normal, additional evaluation may be warranted. In this case the abnormality was detectable on 2D time-of-flight MRA and contrast digital subtraction arteriography. Since MRA has become a commonly used initial screening test for carotid stenosis, it is important to understand the possibility of false-negative results.