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Carotid

  1. 1. Imaging 1. Carotid Duplex Ultrasound 2. CT angiography 3. MR angiography 4. Cerebral Angiography (gold standard)
  2. 2. Carotid ultrasound shows whether a waxy substance called plaque has built up in your carotid arteries. The buildup of plaque in the carotid arteries is called carotid artery disease.
  3. 3. Carotid Atherosclerosis – Progession of Dz Plaque Formation Plaque ulceration Formation of Thrombus Further Stenosis or Occlusion Release of Emboli Plaque Enlargement Decrease Cerebral Flow Decreased or Absent Flow
  4. 4. Over time, plaque can harden or rupture (break open). Hardened plaque narrows the carotid arteries and reduces the flow of oxygen-rich blood to the brain. If the plaque ruptures, a blood clot can form on its surface. A clot can mostly or completely block blood flow through a carotid artery, which can cause a stroke. A piece of plaque or a blood clot also can break away from the wall of the carotid artery. The plaque or clot can travel through the bloodstream and get stuck in one of the brain's smaller arteries. This can block blood flow in the artery and cause a stroke.
  5. 5. Who Needs Carotid Ultrasound? 1. Had a stroke or mini-stroke recently. During a mini-stroke, you may have some or all of the symptoms of a stroke. However, the symptoms usually go away on their own within 24 hours. 2. Have an abnormal sound called a carotid bruit in one of your carotid arteries. Your doctor can hear a carotid bruit using a stethoscope. A bruit might suggest a partial blockage in your carotid artery, which could lead to a stroke. 3. Blood clots in one of your carotid arteries 4. A split between the layers of your carotid artery wall (dissection). The split can weaken the wall or reduce blood flow to your brain.
  6. 6. ULTRASOUND OF THE CAROTIDS - NORMALULTRASOUND OF THE CAROTIDS - NORMAL Normal carotid bifurcation. Common carotid artery (CCA). Internal carotid artery (ICA). External carotid artery (ECA)
  7. 7. Normal Common Carotid artery (CCA). Note the smooth echogenic intimal surface.
  8. 8. The CCA is readily visible. Locate it in transverse and rotate into longitudinal. The CCA will have a doppler trace that is representative of both upstream and down stream influences. Normal PSV for the CCA is usually less than 100cms./sec
  9. 9. Assess the bifurcation in transverse. Rotate on the ECA origin to sample it longitudinally. The ECA waveform is high resistance and may have retrograde flow in diastole. A 'temporal-tap' (TT) was employed here to confirm it was the ECA. The normal range of PSV (peak systolic velocity) for the ECA is from 77 cms./sec. to 115 cms./sec.
  10. 10. The ICA will have low resistance flow, with constant forward flow during diastole. The ICA origin incoporates the bulb which may create a degree of turbulent flow. Normal Carotid bifurcation with the ICA bulb and branch off the ECA.
  11. 11. Distal ICA scan plane. You may only be able to see a few cm of the ICA if there is a high bifurcation. Unless the vessel is tortuous, you should see a low resistance waveform with a clean spectral window beneath the trace. The normal PSV (Vmax in our image), ranges from55 to 88 cms./sec. in the ICA
  12. 12. Transverse bifurcation scan plane. These transverse images show the difference in ICA-bulb vs ECA at the bifurcation and then approximately 1cm further distal.
  13. 13. From the mid-distal CCA slide and angle posteriorly to visualise the cervical transverse processes and the vertebral artery. The vertebral arteries can be variable in diameter. They should always demonstrate antegrade flow (toward the brain) and be low resistance similar to the ICA.
  14. 14. Calcific lesions of carotid arteries These ultrasound images of a young, asymptomatic adult female patient reveal multiple calcific plaques of the common carotid arteries of both sides. The intimal plaques measure 1.5 to 4mm. in size. These sonographic images are diagnostic of dystrophic calcification of the intima of the carotid arteries. Such lesions are very unlikely to cause stroke or thromboembolic events and are hence of little significance.
  15. 15. Intima-media thickness (IMT) of carotid artery The carotid artery/ arteries consist of 3 layers- the intima (the inner most thin layer of endothelium), the middle layer or media (formed by smooth muscles) and the outermost layer- the adventitia (formed by loose connective tissue. Normal common carotid artery thickness should be less than 0.9 mm.
  16. 16. This middle aged male patient had a recent partial stroke affecting the left side of face and left upper limb. The B-mode ultrasound images of the right Common carotid artery show an atheromatous plaque of the lower third of the vessel. This plaque is non calcific and shows no evidence of ulceration. The Color Doppler images of the common carotid artery show no significant obstruction to blood flow in this artery. Possibly, there might have been a small embolic episode some time ago resulting in cerebral ischemia on this side.
  17. 17. This plaque also shows ulceration of the surface which further complicates the situation increasing the possibility of embolism. Color Doppler ultrasound image above shows no significant obstruction (less than 50 % stenosis) to the flow through this area of the carotid artery.The color Doppler and spectral Doppler ultrasound images show and confirm the extent of ulceration of the surface of the carotid plaque. The degree of stenosis of the common carotid artery does not appear to be significant.
  18. 18. Ultrasound and color Doppler images of the right Common carotid (CCA) and ICA (internal carotid) arteries show increased peak systolic velocity in both these vessels. However, no major pathology was seen on the right side. The right ECA (external carotid artery) also showed similar changes .The left CCA shows marked high resistance flow with absent diastolic flow and in fact there is flow reversal during diastole. Clearly there is a major pathology on the left side.
  19. 19. Ultrasound and color Doppler images of the right Common carotid (CCA) and ICA (internal carotid) arteries show increased peak systolic velocity in both these vessels. However, no major pathology was seen on the right side. The right ECA (external carotid artery) also showed similar changes .The left CCA shows marked high resistance flow with absent diastolic flow and in fact there is flow reversal during diastole. Clearly there is a major pathology on the left side.

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