Craniocervical artery dissection: MR imaging and MR angiographic findings

Abstract

Dissection of the carotid and vertebral arteries is a not so uncommon cause of stroke and has to be considered as a differential diagnosis especially in younger patients. Therapeutic and prognostic implications are different from those in extracranial atherosclerotic disease. Dissection results from hemorrhage into the vessel wall usually between the layers of the media. Digital subtraction angiography (DSA) depicts the resulting luminal compromise that may reveal some typical, but not specific, findings. The same is true for non-invasive angiographic techniques such as time-of-flight magnetic resonance angiography (MRA) and computed tomography angiography (CTA), which have shown accurate results compared with DSA. The main advantage of these techniques is the direct visualization of the vessel wall confirming the intramural hematoma. This is achieved best with MR imaging due to the high signal of blood degradation products on T1- and T2-weighted images. Therefore, MRI in combination with MRA is presently the method of choice for initial diagnosis and follow-up of craniocervical artery dissection (CCAD). In some questionable cases, CTA is a non-invasive alternative that is independent of flow phenomena.

Two cases of spontaneous middle cerebral arterial dissection causing ischemic stroke

“…In our patients, DSA showed a double lumen, which is one of the pathognomonic findings in arterial dissection. The demonstration of a surrounding hematoma by MRI [7] or CTA [8] is another pathognomonic finding of arterial dissection. In our patients, no intramural hematoma was detected on the T1-or T2-weighted MRI images, which were taken 3 weeks and 2 months after the onset of the neurologic problems, respectively.…”

Ischemic stroke: carotid and vertebral artery disease

“…Although DSA was the classic gold-standard imaging modality, DUS, CT/CTA and MRI/MRA have demonstrated an excellent accuracy for the diagnosis of extracranial arterial dissection [27] and digital angiography may be reserved for cases undergoing endovascular treatment and/or if there is a suspicion of underlying vascular pathology, intracranial extension not demonstrated by the non-invasive methods.…”

“…MRI and CT show the mural haematoma depicted as an eccentric vessel wall enlargement causing the stenosis of the vessel [24,27]. In the acute phase, CT has the advantage to depict the haematoma as a hyperdense mural lesion [24,27]. However, MRI shows the mural hematoma during the sub-acute phase with the use of fat suppressed T1-weighted axial images [24,27] (Fig.…”

“…2a). MRI and CT show the mural haematoma depicted as an eccentric vessel wall enlargement causing the stenosis of the vessel [24,27]. In the acute phase, CT has the advantage to depict the haematoma as a hyperdense mural lesion [24,27].…”

“…The commonest angiographic signs of dissections are the irregular narrowing, tapered stenosis/occlusion, dissecting aneurysms, double lumen and intimal flapping [23][24][25]27] (Fig. 2a).…”