Carotid artery dissection, case 1

This 52 years old male presented to the emergency room complaining of numbness and mild paresis of the left arm.
Doppler ultrasound revealed the presence of tight stenosis of the right internal carotid artery, distal to its origin. The subsequent 3D TOF MRA also showed progressive stenosis of the internal carotid artery above the carotid bifurcation, similar to the angiographic string sign. The T1-weighted spin-echo study demonstrated the presence of subintimal methemoglobin suggestive of arterial wall dissection.
The patient was treated with anticoagulants and became asymptomatic within a week. A follow-up MRA performed one month later showed complete recanalization of the internal carotid artery.

Examination 1
Fig.1 Transverse T1-weighted spin-echo images with a caudally positioned presaturation slab. The signal void of the right internal right carotid artery suggests stenosis when compared to the left and an area of high signal intensity is seen within its lumen, consistent with subintimal methemoglobin (arrow).
Fig.2 Sagittal targeted MIP reconstructions with angular differences of the right carotid artery bifurcation from a 3D TOF MRA acquisition data set.
The typical MRA appearance of a dissection, with progressive stenosis of the internal carotid artery is demonstrated (arrows).

Examination 2 (one-month follow-up)
Fig.3 Transverse T1-weighted spin-echo images with caudally positioned presaturation. Reappearance of the normal signal void of the right internal carotid artery (arrow).
Fig.4 Sagittal targeted MIP reconstructions with angular differences of the right carotid artery bifurcation from a 3D TOF MRA acquisition data set showing the complete recanalization of the right internal carotid artery.

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