TCD

Question 1

Normal order of mean flow velocities in TCD?

Answer 1

MCA > ACA > siphon > PCA > BA > VA

Question 2

If CHF, anemia, circulatory conditions, how do you determine MCA stenosis?

Answer 2

Use focal MFV difference of >30% between stenosis and adjacent arterial segments.

Question 3

Criteria for indirect flow disturbance in MCA?

Answer 3

1. turbulence distal
2. compensatory flow diversion via ACA
3. low frequency noise
4. distal MCA microembolic signals

Question 4

According to Alexandrov, a proximal MCA stenosis of >70% will produce a stenotic/prestenotic PSV ratio of ??

Answer 4

3:1 or greater.

Question 5

blunting

Answer 5

slow systolic upstroke, slow diastolic downstroke, low velocities, reduction of MCA MFV less than ACA or any other intracranial arteries.

Question 6

MCA stenosis/near occlusion is often accompanied by what?

Answer 6

flow diversion to ACA.

Question 7

For DOPPLER, sample volume corresponds to what?

Answer 7

the “time that the machine is listening” to the blood. Tegeler says it corresponds to the “gate”.

Question 8

Alexandrov: when should you suspect intracranial stenosis?

Answer 8

1. normal hierarchy of flow velocity is DISRUPTED by MFV > 20% between arteries; 2. focal velocity increase

Question 9

Lindegaard ratio?

Answer 9

MFV (MCA) / MFV (ICA) (ipsilateral)

Question 10

> 80 cm/s and LR 3-4?

Answer 10

Hyperemia + possible mild spasm

Question 11

> 120 cm/s and LR 3-4?

Answer 11

Hyperemia + mild spasm

Question 12

> 120 cm/s and LR 4-5?

Answer 12

Hyperemia + moderate spasm

Question 13

> 120 cm/s and LR 5-6?

Answer 13

Moderate spasm

Question 14

> 180 cm/s and LR =6

Answer 14

mod-severe spasm

Question 15

> 200 cm/s and LR>6

Answer 15

severe spasm

Question 16

> 200 cm/s and LR 4-6?

Answer 16

Hyperemia + moderate spasm

Question 17

> 200 cm/s and LR 3-4?

Answer 17

Hyperemia + mild spasm

Question 18

> 200 cm/s and LR

Answer 18

Hyperemia

Question 19

PI formula + meaning

Answer 19

PI = (PSV-EDV) / MFV

Means the velocity change as proportion of mean velocity.

Question 20

OA angle of insonation

Answer 20

15 degrees.

Question 21

How do you reduce aliasing?

Answer 21

“drop the baseline”; reduce sample volume; increase scale (scale = 1/2 * PRF); decrease the depth (increase PRF and therefore the Nyquist limit)

Question 22

M2 depth, direction, velocity?

Answer 22

30-45 mm;

Question 23

M1 depth, direction, velocity?

Answer 23

45-65 mm; towards;

Question 24

A1 depth, direction, velocity?

Answer 24

62-75 mm; away;

Question 25

A2 depth, direction, velocity?

Answer 25

45-65 mm; TOWARDS;

Question 26

ICA siphon depth, direction, velocity?

Answer 26

60-64 mm; BIDIRECTIONAL;

Question 27

OA depth, direction, velocity?

Answer 27

50-62 mm; towards; variable velocity

Question 28

PCA depth, direction, velocity?

Answer 28

60-68 mm; BIDIRECTIONAL;

Question 29

BA depth, direction, velocity?

Answer 29

80-100+mm; away;

Question 30

VA depth, direction, velocity?

Answer 30

45-80 mm; away;

Question 31

Manual MFV calculation?

Answer 31

MFV = (PSV + 2*EDV) / 3

Question 32

STOP criteria?

Answer 32

TAMM (time-averaged mean of maximum) velocity > 200 cm/s in MCA and/or ICA. Child w 2 or more TAMM>200 exams should be offered exchange transfusion.

Question 33

typical findings in Doppler for subclavian steal?

Answer 33

Systolic flow reversal in VA + low-resistance flow in SCA.