Ch 13 Transcranial Doppler

Question 1

What is transcranial doppler (TCD)?

Answer 1

Imaging technique of the intracranial ICA + vessels within the circle of willis

Question 2

What vessels are in the circle of willis?

Answer 2

ICA, MCA, vertebral arteries, etc.

(not ECA b/c it does not supply blood to brain)

Question 3

Which blood vessels connect the extracranial cerebrovascular system with the circle of willis?

Answer 3

ICA’s + vertebral arteries

Question 4

What probe should be used for TCD?

Answer 4

-Low frequency (2-5 MHz)
-Phased array probe

Question 5

What are the names of the acoustic windows?

Answer 5

-Temporal (m/c)
-Occipital
-Opthalamic (l/c)

Question 6

What is the m/c acoustic window used?

Answer 6

Temporal

Question 7

What vessels are imaged from the temporal window?

Answer 7

-MCA
-ACA (anterior cerebral artery)
-Terminal ICA
-PCA (posterior cerebral artery)

Question 8

What vessels are imaged from the foramen magnum/suboccipital window?

Answer 8

-Both vertebral arteries
-Basilar artery

Question 9

What vessels are imaged from the orbital window?

Answer 9

Opthalamic artery

Question 10

What other considerations should be given when imaging from the orbital window?

Answer 10

Transmit power should be reduced to 10%

Question 11

What TAPV velocities do we expect to see in the MCA, ACA, PCA + basilar arteries?

Answer 11

MCA: 60 cm/s
ACA: 50 cm/s
PCA: 40 cm/s
Basilar: 40 cm/s

Question 12

What direction of flow should we see in the MCA?

Answer 12

Forward flow above the baseline in the ipsilateral MCA

Question 13

What is the standard probe orientation from the temporal window?

Answer 13

Indicator should point towards pt’s nose

Question 14

What makes TCD imaging challenging?

Answer 14

-Imaging through bone
-Size of vessels

Question 15

What is TAPV?

Answer 15

-Time average peak velocity
-It is the peak velocity throughout a cardiac cycle + its average

Question 16

Why is TCD useful?

Answer 16

-Surveillance after subarachnoid hemorrhage
-Sickle cell disease
-Intracranial vascular obstruction/stenosis
-RT to LT shunts
-Perioperative monitoring
-Detect/follow up intracranial aneurysms
-Evaluate AVMs (arteriovenous malformations)
-Cerebral vascular reserve
-Brain death

Question 17

What kind of imaging settings should we use with TCD?

Answer 17

-Select TCD presset
-Set depth to 15cm (to show contralateral cranium)
-Reduce depth to 7.5cm now
-Set gain higher than normal
-Set TGCs low in near field + higher in mid/far field
-Set frequency to 2-3 MHz
-Set focal zone to 3-8cm
-Turn off harmonics
-Use frame averaging with CD
-Can use zoom
-Use larger SVB for spectral doppler