Chapter 17 Flashcards
Group 1
The 5 Requirements of Contrast Agents
-Safe
-Metabolically Inert
-Long Lasting
-Strong reflector of ultrasound
-Small enough to pass through capillaries
If the fundamental frequency 5 what is the harmonic frequency?
10
What’s the synonym for harmonic imaging?
Second harmonic frequency
Harmonic frequency sound arises from ____ behavior
Non linear
What does pulse inversion reduce?
Temporal resolution
What’s the major disadvantage of pulse inversion?
Degrades temporal resolution
What improves spatial resolution
Pulse inversion
Frame rate is 1/2 of the ____ _____
Fundamental frequency
Harmonics are typically ___ of the fundamental
Twice
What are the two methods are being isolated from the fundamental beam
-pulse Inversion harmonics
-power modulation harmonics
When dealing with contrast harmonics, does high pressure point shrink or expand the bubble?
Shrink
Which is stronger contrast harmonics or tissue
Contrast
Does sound move faster in compression or rarefraction?
Compression
Resonance is
The nonlinear (uneven) changes in bubble size
Best harmonic effect is in the ____ field
Mid
When is harmonics the strongest?
In the far field
Will weak or strong beams create harmonics?
Strong
What will only make harmonics?
The strong, central part of the beam
What are the two ways harmonics are processed
- Pulse inversion harmonics (most common)
- Power modulation harmonics
T/F Two pulses are sent down each scan line, the second pulse is 3x the size of first one sent.
False. It’s 2x
What happens if MI is high?
The bubbles expands too much and pop.
If MI is too low
The bubbles contract and expand evenly(no harmonics)
What are the two contrast agent characteristics
- The nature of the outer shell
- The gas that fills the microbubbles
When are contrast agents created?
During reflection
