Magnetic resonance imaging and dynamic CT scan in cervical artery dissections

The typical magnetic resonance imaging picture of arterial dissection, namely, a narrowed eccentric signal void surrounded by a semilunar signal hyper-intensity (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 computed tomography, may provide evidence of mural hematoma, but there has been no systematic evaluation of this technique. The aims of this study were to assess both the sensitivity of routine 0.5-T magnetic resonance imaging for the detection of a typical picture of cervical artery dissection and the value of dynamic computed tomographic scans to provide evidence of dissecting hematoma.

Fifteen consecutive patients 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 the site of the dissection suggested by angiography.

A typical magnetic resonance imaging picture of cervical artery dissection was observed in 12 of 15 (80%) patients and in 13 of 19 (68%) dissected vessels. The sensitivity of magnetic resonance imaging was higher in internal carotid (78%) than in vertebral (60%) dissections and in stenotic-type dissections (85%) than in occlusive or aneurysmal-type dissections. The dynamic computed tomographic scan showed the mural hematoma in 11 of the 12 (92%) patients and in 12 of 15 (80%) dissected vessels.

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 imaging will demonstrate no typical abnormality. Dynamic computed tomographic scans are a sensitive neuroimaging procedure to confirm the presence of the mural hematoma, but it needs to be directed by prior angiography.