Dopplers

Question 1

What does it mean for masses that exhibit higher mean flow velocities?

Answer 1

More likely to be malignant

Question 2

What range of velocities are more indicative for malignant masses?

Answer 2

25-40cm/s
- anything lower is more commonly benign

Question 3

What location of a carcinomas have higher velocity’s (PSV and RI)?

Answer 3

Within the centre of the mass
- compared to the periphery (which are lower)
- benign have comparable velocity’s throughout

Question 4

What increases suspicion for malignancy with doppler?

Answer 4

Multiple vessels supplying a lesion

Question 5

What happens with inflammation (eg. Mastitis) will be demonstrated compared to normal tissue?

Answer 5

Increase in flow

Question 6

What does doppler represent?

Answer 6

The mean frequency of the moving reflectors being sampled in multiple sample volumes within the colour box

Question 7

What are 5 advantages to doppler?

Answer 7

1. Simultaneous real time presentation of blood flow and 2D greyscale image
2. Rapid prediction of abnormal flow areas for further assessment
3. Immediate determination of flow direction based in pixel colour
4. Assigned colour varices with velocity of reflectors (lighter colours indicate higher velocities)
5. Ability to assign a specific colour to a given velocity (eg. colour tagging)

Question 8

What are 5 limitation to doppler?

Answer 8

1. Colour represents only mean doppler shift frequency or velocity, not the entire range as in PW spectral analysis
2. Increased time required to process many samples along numerous scan lines often result in reduced image line density and/or frame rates
3. Colour information is based on motion, not necessarily flow, therefore patient or prob motion may be misleading
4. Aliasing occurs at lower velocities because of the lower pulse repetition frequencies used in colour systems
5. Angle dependence results in no flow at 90 deg angles

Question 9

What does power doppler do?

Answer 9

Assigns a colour value to the various doppler shift amplitudes found in the doppler signal
- rather than a mean doppler shift frequencies that are used with colour doppler

Question 10

What are 4 advantages to power doppler?

Answer 10

1. Angle independence
2. Freedom of aliasing
3. Higher sensitivity than colour flow doppler that allows for deeper penetration and the detection of smaller vessels *
4. Extremely sensitive to slow flow

Question 11

What are 3 limitations for power doppler?

Answer 11

1. Does not provide information regarding the characteristics of blood flow
2. Does no provide information about flow velocity
3. Does not provide blood flow direction

Question 12

What do malignant breast lesions demonstrate with vascularity compared to benign lesions? *

Answer 12

Significantly higher mean flow velocities