Contrast Enhanced MRA of Dissection of the Carotid Artery

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A

Clinical History: 
This 69-year-old man presented to the angiography department with a single episode of amaurosis fugax 6 months ago. Since that time he has been treated with thrombocyte aggregation inhibitors. Clinical symptomatology includes headaches and vertigo.

Diagnosis:
Long-segment dissection of the right internal carotid artery.

MR Technique: 
The MRA was acquired on a 3.0 T Siemens Magnetom Tim Trio using the 12-element head matrix coil in combination with the neck matrix, one body matrix and one cluster of the inbuilt spine matrix. A 3D fast low angle shot (FLASH) sequence (TR/TE – 3.28/1.16 ms, voxel size 0.7×0.8×0.8mm³, acquisition time 18 sec) in the coronal orientation was acquired three times: non-enhanced, during the arterial phase and during the venous phase. A test bolus technique with 1 ml of 0.5 M gadolinium-chelate was used to determine the patient’s circulation time. For the MRA, 0.1 mmol/kg of a 0.5 M formulation gadolinium-chelate was injected at 1.5ml/sec followed by a 30 ml saline chaser at the same flow rate. In addition, T2w-TSE images (TR/TE 6551/103ms, voxel size 0.5×0.7x5mm³) of the brain were acquired before contrast agent injection.

Imaging Findings:
In the region of the right carotid bulb a hyperintense structure can be appreciated on the non-enhanced T1w mask images of the MRA (A) that most likely represents mural hemorrhage involving the right internal carotid artery. In the arterial phase MRA (B), the right internal carotid artery has a markedly attenuated lumen over the entire course of the vessel consistent with a dissection of the internal carotid artery. No false lumen can be seen. The dissection can also be seen well on the axial T2w images of the brain (C) where there is abnormal high signal corresponding to mural hemorrhage involving the petrous portion of the internal carotid artery.