TCDI combines real time B-Mode imaging of cerebral parenchyma with color Doppler imaging and spectral Doppler analysis of the major intracranial arteries. The standard examination protocol includes bilateral assessment of the distal extracranial ICA, ACA, MCA, PCA, vertebral and basilar arteries.

• Primarily used to assess stroke risk in children with sickle cell disease and to detect and monitor vasospasm following spontaneous subarachnoid hemorrhage
• Mean flow velocities and ratios remain the primary criteria for diagnosis of cerebrovascular disease
  • Waveforms obtained at 2-5mm increments with a 3-6mm sample volume size
  • Spectral analysis includes peak systolic velocity, end diastolic velocity, systolic upstroke or acceleration time, pulsatility index, and time-averaged maximum mean velocity
  • Angle corrected flow velocities may be higher than non-angle corrected flow velocities (should use a zero degree angle)
  • Most diagnostic standards are based on non-imaging TCD studies
• Provides accurate B-Mode and color Doppler imaging of intracranial anatomy
  • Gray scale imaging of bony landmarks or parenchymal abnormalities
    • lesser wing of the sphenoid bone, petrous ridge of the temporal bone and cerebral peduncles
  • Color Doppler imaging of the major intracranial arteries
    • Should depict the ACA, MCA, PCA and vertebrobasilar arteries
    • May detect intracranial aneurysms ≥ 6mm in size
• Limitations compared to TCD remain:
  • poor beam penetration with lower vessel detection rates
  • suboptimal monitoring of emboli or vasomotor reactivity testing

Transcranial Doppler (TCD)

TCD provides spectral Doppler analysis of the major intracranial arteries. Diagnostic criteria should be based on published studies or internally validated criteria. The majority of reference standards were obtained with non-imaging TCD equipment. The standard examination protocol includes bilateral assessment of the distal extracranial ICA, ACA, MCA, PCA, vertebral and basilar arteries.

• TCD can be used to assess stroke risk in children with sickle cell disease and to detect and monitor vasospasm following spontaneous subarachnoid hemorrhage.
• Provides information related to intracranial stenosis or occlusion and cerebral circulatory arrest.
• Gold standard to detect, localize and quantify cerebral embolism in real-time
• Useful for monitoring thrombolysis of acute intracranial occlusions, detecting extracranial ICA stenosis, cerebral microembolism, right-to left cardiac shunts and to assess cerebral vasomotor reactivity
• Mean flow velocities and ratios are the primary criteria for diagnosis of cerebrovascular disease
  • Waveforms obtained at 2-5mm increments with a 3-6mm sample volume size
  • Vessel identification is based on depth and direction of flow
  • Spectral analysis includes peak systolic velocity, end diastolic velocity, systolic upstroke or acceleration time, pulsatility index, and time-averaged maximum mean velocity
  • Calculate mean flow velocity ratios
  • Evaluate Doppler waveform characteristics
  • Document randomly occurring high intensity signals (HITS) associated with embolic phenomenon
• Benefits of TCD when compared to TCDI:
  • better beam penetration and vessel detection rates
  • can quickly evaluate intracranial arteries to perform provocational testing, monitoring of emboli and vasomotor reactivity testing