Sample Protocol for Performing Extracranial Cerebrovascular Duplex Examinations Purpose



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Sample Protocol for Performing Extracranial

Cerebrovascular Duplex Examinations



Purpose: Extracranial duplex examinations are performed to assess the cervical carotid arteries, common carotid, internal carotid, external carotid and vertebral arteries, for hemodynamic changes and plaque morphology.
INDICATIONS:


  • Cerebrovascular Accident (CVA)

  • Transient ischemic attacks

  • Visual disturbances

  • Amaurosis Fugax

  • Carotid bruit

  • Follow up of known stenosis

  • Post-op or post-intervention

  • Trauma

  • Vertebral Insufficiency


CONTRAINDICATIONS:


  • Patients with recent cervical surgery

  • Patients who are unable to lie flat

  • Patients who are unable to cooperate due to mental status changes or involuntary movements


EQUIPMENT:


  • Duplex ultrasound with color flow Doppler with transducer frequencies ranging from 4 -9 MHz.


PATIENT PREPARATION:


  • Introduce yourself to patient

  • Verify patient identity according to hospital procedure

  • Explain the test

  • Obtain patient history including symptoms

  • Place the patient in a supine position


GENERAL GUIDELINES:


  • A complete examination includes evaluation of the entire course of the accessible portions of each vessel.

  • Bilateral testing is considered an integral part of a complete examination.

  • Limited examinations for recurring indications may be performed as noted.

  • Variations in technique and documentation for assessment of peripheral vascular interventions (i.e., stents), must be described.


TECHNIQUE:


  • Equipment gain and display settings will be optimized while imaging vessels with respect to depth, dynamic range and focal zones.

  • Color flow Doppler will be added to supplement B-mode images with proper color scale to demonstrate areas of high flow and color aliasing.

  • Power Doppler will be used to validate low flow states or occlusions.

  • Cursor sample size will be small and positioned parallel to the vessel wall and/or direction of blood flow.

  • A spectral Doppler angle of 60 degrees or less will be used to measure velocities.

  • Spectral Doppler gains will be set to allow a spectral window and optimized to reduce artifact.

  • Areas of suspected stenosis or obstruction will include spectral Doppler waveforms and velocity measurements recorded at and distal to the stenosis or obstruction.

  • Sites of intervention (i.e., stents) will include spectral Doppler waveforms and velocity measurements from the proximal, mid and distal sites.

  • Plaque should be assessed and characterized.


DOCUMENTATION:


  • Duplex evaluation is performed bilaterally starting with the right side.

  • Long axis B-mode images must be obtained from:

    • Common carotid artery (CCA)

    • Carotid artery bifurcation (if both the internal carotid artery (ICA) and the external carotid artery (ECA) are not visible in one image, take an image of each with the bifurcation)

    • Internal carotid artery (ICA)

  • Spectral Doppler waveforms and velocity measurements must be documented from:

    • Proximal CCA peak systolic velocity (PSV)

    • Mid CCA PSV

    • Proximal ICA PSV and end diastolic velocity (EDV)

    • Mid ICA PSV and EDV if stenosis is present

    • Distal ICA PSV and EDV

    • ECA PSV (temporal tap may be used to identify)

    • Vertebral Artery PSV

  • The ICA/CCA ratio should be calculated using a normal CCA PSV and the highest ICA PSV.


PROCESSING:


Sample Protocol for Performing Extracranial Cerebrovascular Duplex Examinations



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