1. Introduction to Carotid Ultrasound and Transcranial Doppler Ultrasound
Ryan Hakimi, DO, MS
Director, Critical Care Neurology
Assistant Professor
Department of Neurology
The University of Oklahoma Health Sciences Center
January 16, 2015

2. Disclosures
Many of the slides have been adapted from slides presented at the American Society for Neuroimaging Annual Meetings by my mentors
FINANCIAL DISCLOSURE
Nothing to disclose
UNLABELED/UNAPPROVED USES DISCLOSURE
Andre Alexandrov, MD Zsolt Garami, MD Charles Tegeler, MD Alex Razumovsky, PhD

3. Objectives
Review the basic principles of carotid ultrasound (CUS) and transcranial Doppler ultrasound (TCD)
Illustrate the process of plaque morphology and assignment of range of carotid stenosis
Illustrate the process of determining vasospasm by TCD
Discuss some of the current applications of TCD 3

4. Principles of Ultrasound
Blood flow velocity through a cross sectional area of a particular vessel (cm/s)
Blood flow velocity is directly related to Doppler shift
If you measure the Doppler shift you can derive the blood flow velocity
Carotid ultrasound and transcranial Doppler ultrasound can accomplish this

5. Ultrasound Physics

6. Carotid Ultrasound Indications Ischemic stroke or TIA
Assessment of carotid bruit
Assessment of carotid stenosis or occlusion
Pre-operative assessment for cardiovascular surgery
Post carotid endarterectomy or stenting

7. Principles of Carotid Duplex
Duplex (B-mode and Doppler)
B-mode (brightness mode)
Grayscale, used for visualization of structures and assessment of plaque morphology
Hyperechoic (bright white: bone, calcium), causes a shadow posterior to it
Hypoechoic (black or grey: thrombus)
Doppler velocities (peak systolic and end diastolic)
Used to determine the direction of blood flow
Used to estimate the range of stenosis
Each lab should have own validated parameters of the velocities to be used for assignment of stenosis, not just use published values

8. Assignment of Carotid Stenosis
Carotid Artery Stenosis: Gray-Scale and Doppler US Diagnosis—Society of Radiologists in Ultrasound Consensus Conference
Grant et al., 2003

9. Transverse Right ICA B-Mode
Skin surface
Fat and subcutaneous tissue
internal jugular vein
muscle
common carotid artery
(Transverse Right Proximal Common Carotid Artery)

10. Longitudinal Right ICA B-mode Plaque
Focal irregular, heterogeneous plaque in the R Prx ICA
(Longitudinal Right Proximal Internal Carotid Artery)

11. Right ICA B-mode with Color Doppler
+ Flow
(toward probe)
- Flow
(away from probe)
Patient’s Head
Flow
(away from probe)
(Right Proximal Internal Carotid Artery)

12. Right ICA Doppler Velocities
+ Flow
(away from probe)
- Flow
(away from probe)
Patient’s Head
Flow
(away from probe)
Cardiac irregularity
(Right Proximal Internal Carotid Artery)

13. Report Focal plaque in the right internal carotid artery
No hemodynamically significant stenosis demonstrated in the right internal carotid artery.
High resistance with focal plaque in the right internal carotid artery
Cardiac irregularity was noted

14. Longitudinal Left CCA B-mode Plaque
Plaque with fibrous cap and lipid rich core
Hyperechoic plaque with posterior acoustic shadowing
(Longitudinal Left Mid Common Carotid Artery)

15. Longitudinal Left CCA B-mode Plaque
Heterogeneous plaque with posterior acoustic shadowing
(Longitudinal Left Distal Common Carotid Artery)

16. Longitudinal Left ICA Color Doppler
Noise
(sample volume picking up multiple velocity jets)

17. Carotid US vs Transcranial Doppler US
Carotid Ultrasound
Directly visualize the vessel
Stenosis determined by peak systolic velocity
TCD
Blind insonation
Uses mean velocity

18. Transcranial Doppler Ultrasound

19. TCD Wave

21. TCD Spectra

22. Pulsatility Indices

23. Pulsatility Indices Low PI AVM low ejection fraction
aortic regurgitation
High PI: intracranial atherosclerosis
increased intracranial pressure

24. Insonation of Brain

25. TCD use in Carotid Occlusive Disease
Allows for evaluation of:
Collateral flow
Cerebral embolism
Poor vasomotor reserve i.e. progression of carotid stenosis

26. TCD use in Carotid Occlusive Disease
Slide courtesy Z. Garami, MD

27. Risk of Ipsilateral Stroke: Number of Activated Collaterals (ACA, PCOM, OA)

28. Subarachnoid Hemorrhage
Detection of vasospasm
Clinical exam (usually somnolence or non-focal symptoms), not very sensitive
Daily TCD (non-invasive, 90% sensitivity, often precedes clinical vasospasm)
TCD or CTA can be used to screen for “plasty-able” lesions
Images from
3. all accessed on 1/24/ Cerebrovascular Ultrasound in Stroke Prevention and Treatment 28

29. Thresholds for Anterior Circulation Vasospasm
Should be validated at the given center
Mild vasospasm cm/s, Lindegaard Ratio (MCA velocity/extracranial ICA) 3-4
Moderate vasospasm cm/s, Lindegaard Ratio (MCA velocity/extracranial ICA) 4-6
Severe vasospasm >200 cm/s, Lindegaard Ratio (MCA velocity/extracranial ICA) >6
Less reliable in posterior circulation (due to greater anatomic variance)

30. Data on TCD Monitoring
Courtesy Mauro Oddo, MD

31. Subarachnoid Hemorrhage
Triple-H therapy (hypertension, hypervolemia, hemodilution)
Introduced in 1970’s to prevent delayed cerebral ischemia from vasospasm
Prophylactic triple-H (in absence of vasospasm) does not prevent vasospasm (Treggiari et al. J. Neurosurg 2008)
Double-H therapy (hypertension and hypervolemia as hemodilution is consequence of hypervolemia)
Must be individualized and titrated to clinical exam and TCD
Can result in pulmonary edema, hyponatremia, MI, etc. 31

32. Brain Death Uniform Determination of Death Act
Legally acknowledged brain death as a mechanism of death
Defined death as:
Irreversible cessation of circulatory and respiratory functions OR
Irreversible cessation of all functions of the entire brain, including the brain stem
1. Guidelines for the determination of death: report of the medical consultants on the diagnosis of death to the President’s commission on the ethical problems in medicine and biochemical and behavioral research. JAMA 1981;246:
2. Uniform Determination of Death Act, 12 uniform laws annotated 589 (West 1993 West suppl 1997)

33. AAN recommendations on use of ancillary testing
AAN Clinician Guideline Supplement: Ancillary Testing; Update: Determining Brain Death in Adults

34. Diagnosis of Patent Foramen Ovale (PFO)
Slide courtesy Alex Razumovsky, PhD

35. Diagnosis of Patent Foramen Ovale (PFO)
PFO is a residual channel between the right and left atrium which originally allowed oxygenated placental blood to pass from the right to left atrium bypassing the fetal lungs
Usually closes by age 2, but can persist in 25-30% of the general population

36. Diagnosis of PFO by TCD Agitated saline study Monitor the MCA
Slide courtesy Z. Garami, MD

37. Diagnosing subclavian steal by TCD
Image the vertebral artery
Ischemic cuff test

38. Subclavian Steal Syndrome
Slide courtesy Z. Garami, MD

39. Questions
Thank you
OU Neurology