Transcranial Doppler (TCD)

Question 1

what arteries are included in the circle of willis

Answer 1

anterior communicating artery
anterior cerebral arteries
small portions of distal ICA
posterior communicating arteries
posterior cerebral arteries
- P1- PCA segment from the basilar bifurcation to the P comm
- P2 - distal to the P comm

Question 2

what artery/arteries is NOT part of the circle of Willis

Answer 2

middle cerebral artery (MCA) is an extension of the ICA past the ACA bifurcation but NOT a part of the circle of Willis

Question 3

describe periorbital circulation

Answer 3

the ophthalmic artery branches off the terminal ICA

supraorbital artery arises from the ophthalmic artery and travels anteriorly and superiorly to the eye and joins the ECA via several branches (notably superficial temporal artery)

frontal artery arises from the Opthalmic artery: exits the orbit medially to supply the forehead, also joins with ECA branches

Question 4

what are the 3 acoustic windows for transcranial doppler

Answer 4

transtemporal, transorbital and trasforamenal/suboccipital

Question 5

what is the MHz used and what is the angle of incidence

Answer 5

2 MHz pulsed doppler
zero angle of incidence

Question 6

how do you know if you are on the right vessel when scanning?

Answer 6

depth of sample volume
direction of blood flow
velocity of blood flow
relationship of flow patterns to one another

Question 7

what is used to determine ratio? time average mean velocity or peak systolic velocity

Answer 7

time average MEAN velocity

Question 8

what can be evaluated through transtemporal approach

Answer 8

terminal ICA, MCA, ACA, PCA

appreciate the posterior angulation to insonate the PCA and differentiation of P1 and P2

(see page 193)

Question 9

what can be evaluated through transorbital approach

Answer 9

ophthalmic artery and the carotid siphon

(see page 193)

Question 10

what can be evaluated through suboccipital/transforamenal approach?

Answer 10

distal vertebral and basilar arteries

(see page 193)

Question 11

describe the identification and values of MCA

Answer 11

window: temporal
depth (mm): 30-60
direction: towards
velocity: 55 +/- 12
angulation: anterior/superior

Question 12

describe the identification and values of terminal ICA

Answer 12

window: temporal
depth (mm): 55-65
direction: bi-directional
velocity: 55 +/- 12
angulation: anterior/superior

Question 13

describe the identification and values of ACA

Answer 13

window: temporal
depth (mm): 60-80
direction: away
velocity: 50 +/- 11
angulation: anterior/superior

Question 14

describe the identification and values of PCA

Answer 14

window: temporal
depth (mm): 60-70
direction: P1 TOWARDS/ P2 AWAY
velocity: 39 +/- 10
angulation: posterior

Question 15

describe the identification and values of ophthalmic artery

Answer 15

window: orbital
depth (mm): 40-60
direction: toward
velocity: 21 +/- 5
angulation: medial

Question 16

describe the identification and values of ICA (siphon)

Answer 16

window: orbital
depth (mm): 60-80
direction: supraclinoid = away
genu = bi directional
parasellar = towards
velocity: 47 +/- 14
angulation: varies

Question 17

describe the identification and values of vertebral

Answer 17

window: supocciptal/foramenal
depth (mm): 60-90
direction: away
velocity: 38 +/- 10
angulation: right and left of midline

Question 18

describe the identification and values of basilar

Answer 18

window: supocciptal/foramenal
depth (mm): 80-120
direction: away
velocity: 41 +/- 10
angulation: midline

Question 19

describe sickle cell disease

Answer 19

an inherited disorder of the blood. abnormal oxygen-carrying protein within the red blood cells called hemoglobin causes distorted red blood cells (sickle appearance under a microscope). they are fragile and prone to rupture.

most common inherited blood anemias

Question 20

where do emboli come from

Answer 20

carotid stenosis
cardiac source
- patent foramen ovale (PFO) allows blood/emboli to travel from the venous circulation into the arterial circulation

Question 21

what vessels can be evaluated in transmandibular acoustic window

Answer 21

mid and distal )petrous) segment of the ICA

used primarily for emboli monitoring