Temporal resolution*

Question 1

Temporal resolution

Answer 1

ability to detect moving structures on display

Question 2

What is the one factor that determines temporal resolution?

Answer 2

Frame rate

Question 3

What is the relationship between frame rate and temporal resolution?

Answer 3

Directly related

Question 4

What are the two factors that determines frame rate?

Answer 4

Scanning depth- depth and FR are inversely related.
# of pulses/frame: which is inversely related to FR

Question 5

What two factors limits frame rate?

Answer 5

Speed of sound- directly related to FR
depth of view- inversely related to FR

Question 6

What are the three factors that determines the number of pulses/per frame?

Answer 6

-Sector size: scan pulses and sector are directly related
-Line density: LD & TR are inversely related
-# of focal points: is inversely related to TR

Question 7

What sector width is best for temporal resolution?

Answer 7

Narrow sector width because it requires less line and less pulses

Question 8

What degrades TR?

Answer 8

Increasing depth
High line density
More pulses
Any compounding
Slower pulse
Fill-in interpolation
Phased array transducers
Multi-focus

Question 9

What improves temporal resolution?

Answer 9

Decrease depth
Low line density
Fewer lines/pulses
Faster pulse speeds
Write magnification
Higher PRF
high duty factor
low PRP
shallow imaging(shallow depth) - greatest effect
decrease sector angle

Question 10

How does higher PRF & Duty factor improve TR?

Answer 10

Any time you have high PRF and high duty factor you have a low depth which is good for TR

Question 11

What has the greatest effect on temporal resolution?

Answer 11

Shallow imaging or shallow depths

Question 12

What happens to your frame rate when you use pulse inversion?

Answer 12

Time required to create a frame is doubled so your frame rate is halved and TR is reduced

Question 13

How does parallel beam forming improve TR?

Answer 13

It allows two or more received signals, producing two or more scan lines for each transmitted pulse, enabling higher FR

Question 14

Persistence/temporal compounding/temporal averaging

Answer 14

Smoother image by producing a history of older images on the most current frame

Question 15

How does temporal compounding affect TR?

Answer 15

It degrades TR and it’s actually more effective with slower moving structures

Question 16

What improves S:N?

Answer 16

Output power
Coded excitation
Rejection
Spatial compounding
Frequency compounding
Pulse inversion
Persistence
Color priority
Harmonic imaging