TCD Acoustic Windows

Two Scanning Planes: 

  1. Axial scan
    1. Mesencephalic view
      1. Probe parallel to zygomatic arch
      2. Identify midbrain (“butterfly”) at about half of the scanning plane
      3. Can identify Pcomm in 75%
    2. Diencephalic view
      1. Tilt transducer 10degrees up
      2. Identify III ventricle, then posteriorly the pineal gland (hyperechogenic) and anteriorly the thalamus and internal capsule
      3. Identify lateral ventricles
  2. Coronal scan
    1. Rotate probe 90degrees from axial position
    2. Identify III ventricle, lateral ventricles, thalamus, internal capsule
    3. Useful for assessment of midline shift

 

Four TCD Acoustic Windows:b9781437714173000127_f12-01-9781437714173

  1. Temporal window
    1. Above zygomatic arch, anterior to tragus
    2. Axial plane, mesencephalic view
    3. Divided into anterior, middle and posterior zones
    4. Identify MCA (M1, M2), A1, P2, P2, C1 of carotid siphon, Acomm and Pcomm, distal end of BAni_2014_62_5_510_144443_f4
  2. Occipital window
    1. Probe on median sub-occipital line
    2. Patient sitting or lying down with head turned to opposite direction, chin lowered toward shoulder
    3. US beam passes through foramen magnum
    4. Visualize intracranial segment of vertebral arteries and basilar trunk
    5. Y shape, with flow moving away from probe
    6. Slight lateral movements to display both AICA, PICA
  3. Orbital window
    1. Transducer perpendicular to eyelid, patient’s eyes closed, looking opposite probe
    2. Insonate ophthalmic artery, C2, C3, C4 carotid siphon
    3. Potential retinal injuries – reduce power by 10-15%
  4. Submandibular window
    1. Transducer underneath angle of mandible in front of masseter muscle, probe toward skull
    2. Allows terminal segment (C5, C6) of ICA and C1 segment of carotid siphon

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MCA: depth of 4.5-6.0cm, blood flow toward probe

Identify sphenoid bone (butterfly wing sign)

 

Reference:

D’Andrea, Antonello et al. “Transcranial Doppler Ultrasonography: From Methodology To Major Clinical Applications”. World Journal of Cardiology 8.7 (2016): 383.

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