Carotid pathology

Source: ASUM 2006 Australasian Journal of Ultrasound in Medicine.

Ultrasound image- Intimal thickening of the CCA.

Ultrasound image- CCA intimal thickening

Ultrasound image-Occlusion of the ICA.

Ulcerated Plaque

  • Careful evaluation of mixed plaque with a rough surface may reveal ulceration of the plaque.
  • This carries a higher risk of embolization and should always be reported.

A transverse ultrasound view of the ulcerated plaque.

Ulcerated Plaque in the proxiaml ICA.
The gap in the calcific plaque on Bmode is the clue.
On colour doppler ultrasound, the large, deep ulceration is easily seen.

Carotid Bypass

If the unusual circumstance of bilateral occlusion or near occlusion is detected, a bypass may be performed. Velocities will be variable, and the normal carotid stenosis criteria cannot be used. Use velocity ratios similar to extremty arteries.

The first image in the following gallery is a schematic of:

The Lt CCA has been excised. A bypass from the lt subclavian artery supplies the Rt CCA to the brain and retrograde down the subclavian artery to the arm.

Ultrasound image- excised Lt CCA.

Ultrasound image- The anastamosis of the Lt to Rt bypass graft into the right CCA.

 Doppler ultrasound demonstrating the appropriate retrograde flow back down the right CCA.

Subclavian Steal Syndrome

  • An occlusion or high grade stenosis in either subclavian artery proximal to the vertebral artery origin can result in blood being syphoned out of the Circle of Willis, retrograde down the vertebral artery to supply the arm.

Arrows indicate normal flow direction in the extra cerebrovascular circulation.

Arrows indicate the flow direction in a right sided subclavian steal syndrome.

Abnormal vertebral flow such a this raises the suspicion of proximal subclavian pathology.

Retrograde vertebral artery in subclavian steal syndrome.

Ultrasound image-monophasic retrograde vertebral flow. Be sure to confirm flow direction by colour flow and poitive/negative. Not merely by above/below the baseline.

Carotid Dissection

  • If a small tear occurs in the wall of an artery, blood can push under the intima, peeling it off the underlying media. As the pressure peels more away, it may occlude the vessel or create an exit leaving an intimal flap.
  • Carotid and vertebral dissections are more often secondary to blunt neck trauma ,such as car accidents,and can result in significant embolic cerebral ischaemia.
A vertebral dissection. vertebral dissection colour doppler

A vertebral dissection. Note the thin echogenic intimal flap.

The colour doppler image demonstrates the filling defect.

The following ultrasound images show a large intimal flap/early dissection of the internal carotid artery.  This was causing a haemodynamically significant disruption to the flow.

Ultrasound image- Intimal flap within the ICA bulb.

Ultrasound image-B flow nicely demonstrates the flow dynamics.

Ultrasound image-Transverse view of the intimal flaps. Note the similarity to a venous valve.

Ultrasound image-Spectral doppler demonstrating the turbulent stenosis caused by the dissection.

Carotid Body Tumour

  • The carotid body is a mass of neural tissue at the carotid bifurcation that assists detecting the oxygen/carbon dioxide levels in the blood going to the brain.
  • The carotid body tumour is a glomus tumour and is hypertrophy of this neural tissue.
  • It presents as an encapsulated firm mass, generally asymptomatic, adjacent to the carotid bulb, between ICA and ECA.
  • Ultrasound of a carotid body tumour shows a well defined homogeneous ovoid mass.

Ultrasound image- Carotid Body Tumour .

 

Ultrasound image- carotid body tumour with power doppler.