Tissue Harmonic Imaging (Lesson 4a)

Question 1

What is harmonic imaging?

Answer 1

A form of signal filtering where fundamental (transmitted) frequencies are filtered out and only second harmonic frequency echoes are accepted

Question 2

What are harmonics?

Answer 2

Natural frequencies that occur from the object

Question 3

What type of resolution does harmonics improve?

Answer 3

Lateral resolution, due to harmonics being generated only int he highest-intensity portion of the beam

Question 4

How does harmonic imaging reduce axial resolution degratation?

Answer 4

A pulse inversion technique is used, so two pulses per scan line rather than one with the second pulse being the inverse of the first

Question 5

With harmonic images, what 2 factors are reduced and degraded?

Answer 5

Frame rate & temporal resolution

Question 6

Tissue harmonic imaging (TSI) improves what?

Answer 6

Improved signal-to-noise ratio and artifact reduction

Question 7

What clinical settings is TSI useful for?

Answer 7

Obesity, hollow structures, deep seated major vessels