MAGNETIC-RESONANCE-IMAGING AND DYNAMIC CT SCAN IN CERVICAL ARTERY DISSECTIONS

Background and Purpose The typical magnetic resonance imaging picture of arterial dissection, namely, a narrowed eccentric signal void surro unded by a semilunar signal hyperintensity (corresponding to the mural hematoma) on T1- and T2-weighted images, has been repeatedly reported , but the sensitivity of magnetic resonance imaging for the diagnosis of cervical dissection is poorly known. Another technique, dynamic com puted tomography, may provide evidence of mural hematoma, but there ha s been no systematic evaluation of this technique. The aims of this st udy were to assess both the sensitivity of routine 0.5-T magnetic reso nance imaging for the detection of a typical picture of cervical arter y dissection and the value of dynamic computed tomographic scans to pr ovide evidence of dissecting hematoma. Methods Fifteen consecutive pat ients with angiographically confirmed extracranial internal carotid (n =9) or vertebral (n=10) dissections were studied using a standardized 0.5-T spin-echo magnetic resonance imaging protocol with axial slices. Twelve of these patients had dynamic computed tomographic scans at th e site of the dissection suggested by angiography. Results A typical m agnetic resonance imaging picture of cervical artery dissection was ob served in 12 of 15 (80%) patients and in 13 of 19 (68%) dissected vess els. The sensitivity of magnetic resonance imaging was higher in inter nal carotid (78%) than in vertebral (60%) dissections and in stenotic- type dissections (85%) than in occlusive or aneurysmal-type dissection s. The dynamic computed tomographic scan showed the mural hematoma in 11 of the 12 (92%) patients and in 12 of 15 (80%) dissected vessels. C onclusions Routine 0.5-T magnetic resonance imaging with axial slices is a sensitive technique for the diagnosis of dissection, but in about 20% of patients with cervical artery dissection magnetic resonance im aging will demonstrate no typical abnormality. Dynamic computed tomogr aphic scans are a sensitive neuroimaging procedure to confirm the pres ence of the mural hematoma, but it needs to be directed by prior angio graphy.