CAROTID Arteries Doppler ultrasound By JALIL HANAFI.pptx

Assessment of Doppler ultrasound in carotid arteries with details

1. SONOGRAPHIC ASSESSMENT OF CAROTID ARTERIES MUHAMMAD JALIL HANAFI MS MIT

2. INDICATIONS: Evaluation of patients with hemispheric neurologic symptoms, including stroke, transient ischemic attack, and amaurosis fugax Evaluation of patients with a carotid bruit Evaluation of pulsatile neck masses Evaluation of patients scheduled for major cardiovascular surgical procedures Evaluation of non hemispheric or unexplained neurologic symptoms Evaluation of patients after carotid revascularization, including stenting Evaluation of suspected subclavian steal syndrome

3. ANATOMY

4. Sonographic anatomy

5. Protocol Patient Position The patient may lie down in the supine or semisupine position with the head slightly hyperextended and rotated 45° away from the side being examined Transducer Higher-frequency linear transducers (7 MHz) are ideal for assessment of the intima-media thickness and plaque morphology, while lowerfrequency linear transducers (7 MHz) are preferred for Doppler examination. In a short muscular neck, if imaging with a linear transducer is impossible, a curved-array transducer (7 MHz) may be helpful to document the anatomy of the carotid bifurcation with color Doppler US

6. The examination sequence: A typical carotid examination takes place as follows : Step 1. The best way to do this is to place the transducer in A transverse plane and to sweep the probe slowly upward from the level of the clavicle to the jaw. This can be done In gray-scale mode and, if needed, with color doppler imaging. This scan is used to obtain an overall evaluation of carotid anatomy Step 2 The transducer position that best displays the carotid vessels in a longitudinal view will typically be from a lateral approach

7. Step 3. Doppler imaging of the CCA Start the survey of the CCA low in the neck, moving upward to the bifurcation. Record a velocity spectrum from the CCA low in the neck record a second waveform close to the bifurcation and the following points should be noted: (1) the measurement point should be 2 to 4 cm below the carotid bulb; (2) care should be taken that the sample volume is squarely within the center of the vessel (3) the doppler angle must be low enough (60 degrees or less) to measure the peak systolic velocity accurately

8. Step 4. Bifurcation survey The carotid bifurcation is imaged with B-mode and color Doppler imaging in both the longitudinal and transverse planes. The purpose of this survey is to confirm the patency of the arteries, to identify and to localize plaque and associated flow abnormalities, and to define the junction of the ECA and ICA or flow divider in order to help define plaque location.

9. Step 5 . Vessel identity Confirm the identity of the ICA and ECA by their Doppler spectral signatures by anatomic features and by performing the temporal tap maneuver The proper identification of the branch vessels is essential because only significant ICA stenoses are treated. Intervention is rare on ECA stenotic lesions and only in cases of complex multiple occlusions of the carotid and vertebral arteries. A color Doppler image of the proximal ECA and ICA should be recorded. As a minimum, a proximal and distal ICA duplex image should be recorded

10. Features That Identify the ECA & ICA

11. Normal doppler waveforms

12. step 6 . Stenosis detection and documentation When a stenosis is present, properly angle-corrected velocity estimates are made in the stenosis Color Doppler images that document the location and length of the stenosis are also recorded Step 7. Evaluation of the vertebral arteries images of each vertebral artery with representative Doppler spectral waveforms, including measurement of the peak systolic and end-diastolic velocities, are recorded. Step 8. Assessment of the subclavian arteries Additional images of the subclavian arteries are acquired either as part of a fixed protocol or as an option in cases of vertebral artery disease.

13. LIMITATIONS Physical challenges such as a short muscular neck, a high carotid bifurcation, tortuous vessels, calcified shadowing plaques, tracheostomy tubes, surgical sutures, postoperative hematoma or bandages, central lines, inability to lie flat in respiratory or cardiac disease or to rotate the head in patients with arthritis, and uncooperative patients may limit the results of carotid US examination

14. OPTimal Scanning Techniques and Doppler SettingS Doppler Equation US equipment calculates the velocity of blood flow according to the Doppler equation: where f is the Doppler shift frequency, f0 is the transmitted ultrasound frequency, V is the velocity of reflectors (red blood cells), (theta, also referred to as the Doppler angle) is the angle between the transmitted beam and the direction of blood flow within the blood vessel (the reflector path), and C is the speed of sound in the tissue (1540 m/sec)

15. The Doppler angle should not exceed 60°, as measurements are likely to be inaccurate. Our preferred angle of incidence is 45°+-4. The optimal position of the sample volume box in a normal artery is in the mid lumen parallel to the vessel wall, whereas in a diseased vessel it should be aligned parallel to the direction of blood flow . In the absence of plaque disease, the sample volume box should not be placed on the sharp curves of a tortuous artery, as this may result in a falsely high velocity reading . If the sample volume box is located too close to the vessel wall, artificial spectral broadening is inevitable.

16. SAMPLE VOLUME BOX AND ANGLE CORRECTION

17. SPECTRAL BROADENING Spectral broadening occurs when there is a wide range of velocities in the Doppler sample volume. There is filling in of the spectral window or area under the spectral line This finding is typically seen with stenosis; however, spectral broadening may be related to technical factors and other causes of turbulent flow. These include the following: A large Doppler sample volume that includes all or most of the artery lumen High gain settings Increased vessel wall motion High velocities contralateral to a severely diseased or occluded ICA Tortuous vessels

18. Color scale adjustment

19. Color gain adjustment

20. Imaging protocol :IMT & plaque B-mode image is taken at the distal common carotid artery. The head of the patient is rotated 45 degrees away from the side being imaged and the probe is held parallel to the artery The probe is kept parallel to the artery so that he double lines of the lumen-intima and media adventitia interfaces are clearly visible on both near and far walls. The location of the common carotid IMT measurement is always below the bulb extending to the right over a distance of approximately 1 cm

21. Plaque imaging

22. Grading of plaque

23. Plaque morphology HOMOGENOUS HETEROGENOUS

24. PLAQUE ULCERATION

25. Vertebral artery & subclavian steal Identification of the vertebral artery is achieved by locating the cca in a sagittal view and sweeping the transducer laterally to the transverse processes of the cervical spine On the basis of the hemodynamic changes in the vertebral artery, there are three types of subclavian steals. In occult steal (minimal hemodynamic changes), pw doppler imaging may show antegrade flow with midsystolic deceleration, which may temporarily convert to a more abnormal waveform Partial subclavian steal corresponds to moderate hemodynamic changes. The PW doppler spectrum shows partially reversed flow. The PW doppler spectrum in occult and partial subclavian steal may resemble the profile image of a rabbit (the “ bunny rabbit” sign) In complete (full) subclavian steal , flow in the vertebral artery is completely reversed . this may be associated with ischemic symptoms in the ipsilateral arm.

26. ANY QUESTION? THANK YOU