Intracranial Cerebrovascular

Question 0

Intracranial doppler imaging is based on what

Answer 0

hemodynamics

Question 1

what did intracranial imaging lag behind

Answer 1

it was difficult to penetrate the skull

Question 2

intracranial imaging initally was developed to detect _________ following a what

Answer 2

vasospasm

subarachnoid hemorrhage

Question 3

what is TCD

Answer 3

transcranial doppler

Question 4

describe TCD

Answer 4

non invasive
portable
painless
safe
inexpensive
repeatable

Question 5

TCD measures and identifies what

Answer 5

measures velocity of flow

indentifies direction of flow

Question 6

what was TCD imaging introduced

Answer 6

1982

Question 7

TCD limitations

Answer 7

operator dependent - steady hand

blind vessel indentification - no image

anatomic variants - ex. incomplete circle of willis

skull difficult to penetrate

Question 8

TCD clinical applications

Answer 8

occlusive disease
cerebral emboli
hemorrhage
sickle cell disease
subclavian steal
head trauma
cerebrovascular disease
stroke
migraine headaches
aneurysms
AV fistulas
vasospasms
eval of brain death
eval of collateral flow

Question 9

how is the blood delivered to the circle of willis

Answer 9

internal carotids and vertebrals form an anterior circulation and a posterior circulation respectively

Question 10

what is the circle of willis

Answer 10

ring that permits communication between the right and left cerebral hemispheres and between the anterior and posterior systems

Thomas Willis in 1664

Question 11

what does the circle of willis consist of

Answer 11

A1 segments of the 2 ACA’s, ACoA, 2 PCoA’s, 2 ICA’s, and P1 segment of the 2 PCA’s

Question 12

describe the anterior circulation system

Answer 12

supplies majority of blood to both hemispheres

vessels: ICA, MCA, ACA, ACoA

Question 13

describe the posterior circulation system

Answer 13

supplies the brainstem

vessels: vertebrals, basilar, PCA, PCoA

Question 14

describe the internal carotid artery

Answer 14

origniates from the CCA

passes through the skull and gives off the FIRST major branch (ophthalmic artery)

gives off the posterior communicating arteries (PCoA) before dividing into middle cerebral arteries (MCA) and anterior cerebral arteries (ACA)

Question 15

Internal carotid artery consists of what parts

Answer 15

cervical
petrous
lacerum
cavernous
supraclinoid
ophthalmic
communication

Question 16

describe the opthalmic artery

Answer 16

first branch of the ICA

important role in collateral pathways

Question 17

what is the portion of the ICA that forms 2 curves

Answer 17

carotid siphon

Question 18

ICA bifurcates into what two terminal branches

Answer 18

anterior cerebral artery (ACA)

middle cerebral artery (MCA)

Question 19

anterior circulation connects via what

posterior circulation connects via what

Answer 19

anterior communicating artery - ACOM

posterior communicating artery - PCOM

Question 20

which vessel can you not see when doing a TCD

Answer 20

anterior communicating artery

Question 21

describe MCA

Answer 21

larger terminal branch of the ICA

branches turn upward to the Sylvian fissure

four segments - M1 to M4

M1 and origin of M2 eval - TCD

Question 22

describe ACA

Answer 22

smaller terminal branch of the ICA

A1 segment eval - TCD

ACA connected by ACoA

Question 23

describe ACoA

Answer 23

can not be visualized with TCD

Question 24

describe PCoA

Answer 24

courses from ICA to join the PCA

Question 25

describe PCA

Answer 25

origniates from basilar P1 segment eval - TCD

Question 26

describe vertebral artery

Answer 26

branches of the subclavian four segments

Question 27

describe basilar artery

Answer 27

union of the vertebral divides into the PCA to form part of the circle of willis

Question 28

characteristics of TCD

Answer 28

phases array PULSED doppler (cw can not be used) 2-5 MHz - for penetration - LOW FREQUENCY TRANSDUCER assume 0 degree angle - shooting straight down the barrel capture the entire circle of willis

Question 29

what is the real time display of all doppler shift frequencies over time

Answer 29

doppler spectral waveform

Question 30

______doppler shift = above the baseline, towards the transducer ______ doppler shift = below the baseline, away from the transducer

Answer 30

positive negative

Question 31

during TCD imaging, the doppler power should be _________ for adequate penetration

Answer 31

increased

Question 32

what is the key for TCD

Answer 32

**depth blue is away and red is towards adjust power and gain

Question 33

what are the four TCD windows

Answer 33

transtemporal transorbital transoccipital, suboccipital submandibular

Question 34

where is the transducer placed for a transtemporal scan

Answer 34

on the temporal bone cephalad to the zygomatic arch, and anterior to the ear

Question 35

transtemporal imaging may be difficult because why

Answer 35

tortuous vessels - not located in up to 30% of patients

Question 36

name the transtemporal vessels

Answer 36

``` MCA ACA MCA/ACA bifurcation - "butterfly sign" PCA ICA ```

Question 37

______ PRF for slower flow in the ACA and PCA

Answer 37

decrease

Question 38

how is transorbital scanning done

Answer 38

patient is supine and the transducer is gently placed on the closed eyelid

Question 39

describe transorbital scanning

Answer 39

opthalmic artery - high resistance carotid siphon decrease power setting ALARA principle

Question 40

how is transoccipital scanning done

Answer 40

transducer is placed on the posterior aspect of the neck inferior to the nuchal crest

Question 41

what vessels will be seen when scanning transoccipitally

Answer 41

vertebral basilar "Y sign"

Question 42

submadicular scanning consists of what vessel

Answer 42

distal ICA

Question 43

how do you achieve good quality color doppler images - TCD

Answer 43

increase color gain appropriately maintain a small sector width and color box change color PRF - depends on hemodynamics be aware of color sensitivity and persistence settings color and interpretation are important for TCD

Question 44

TCD measures ______ flow velocity, not peak

Answer 44

mean

Question 45

know charts for window, arteries, depth, mean velocity, and direction

Answer 45

slides 54-55

Question 46

what 2 things are important when interpreting TCD

Answer 46

experience - w/o is difficult knowledge of anatomy - essential

Question 47

describe interpretations: ``` stenosis? occulusion? vasospasm? sickle cell anemia? vasoconstriction? AV malformation? brain death? ```

Answer 47

stenosis - increased velocities, turbulence occulusion - no flow, insonating (angling) vessel key vasospasm - increased velocities, sequential doppler sickle cell anemia - increased velocities in the ICA and MCA vasoconstriction - hemorrhage AV malformation - increased velocities with low pulsatility, turbulence brain death - suspected

Question 48

physiologic factors of TCD velocities

Answer 48

age - lower velocities with increasing age sex - slight increase in velocities with females hematocrit - velocities increase with anemia HR and cardiac output

Question 49

describe stenosis

Answer 49

focal increases in velocity local turbulence poststenotic drop PRF increased

Question 50

describe occulsion

Answer 50

TCD is limited lack of reliable data

Question 51

describe vasospasm

Answer 51

vasoconstriction of the arteries complication of hemorrhage increase in velocity

Question 52

describe hemorrhage

Answer 52

ruptured aneurysm vascular tumor head trauma

Question 53

describe aneurysm

Answer 53

color flow appearing in an unexpected area wider colo area

Question 54

describe subclavian steal

Answer 54

associated with stenosis or occlusion of subclavian artery vertebral becomes collateral - reversed flow pressure difference of greater than 20 means obstruction on side with lower pressure

Question 55

describe emboli detection

Answer 55

high intensity signal hear a chirp/see a spike

Question 56

describe emboli

Answer 56

use main MCA transient signal higher amplitude unidirectional audio sound - snap

Question 57

describe sickle cell disease

Answer 57

inherited blood disorder screen children cerebral infarction associated with occlusion