Findings:
Axial T2 images high signal crescent sign within the wall of the left extracranial internal carotid artery. Associated contour irregularity and mild narrowing of the vessel on the MRA from the level of the bifurcation to the skull base.
Extra- and the intracranial circulation are otherwise unremarkable. Hypoplastic left vertebral artery with direct origin from the aortic arch is seen.
No intra- or extra-axial mass lesion or collection is identified. The ventricles and sulcal spaces are within normal limits. The midline structures are normal with no midline shift.
A few non-specific white matter lesions are noted in bilateral cerebral white matter.
The brain parenchyma is otherwise unremarkable. No abnormal signal on the diffusion/ADC images is identified. No evidence of any intra or extra-axial enhancement on the postcontrast study.
The pituitary gland is normal.
Minimal mucosal thickening is seen in the left sphenoid sinus. The orbits, paranasal sinuses and mastoid air cells are otherwise clear.
No bony abnormality is seen.
Minimal disc bulging is seen at C6/7. Loss of physiological cervical lordosis is seen.
The central canal and the neural exit foramina are patent.
No paravertebral abnormality is identified.
Impression:
Left-sided internal carotid artery dissection from bifurcations to the skull base level.
Normal intracranial circulation. No evidence of ischaemic event or intracranial haemorrhage.