Ch 16, 17 Quiz Review Flashcards
What the requirements are for contrast?
Safe Metabolically inert Long lasting Strong reflector for ultrasound Small enough to pass through capillaries
Fundamental frequency, what is the harmonic frequency and vise versa?
Harmonic frequency is double the fundamental
What behavior creates harmonics?
Non-linear
Difference between few and many shades of gray?
Few Shades
few choices
bistable
narrow dynamic range
high contrast
Difference between few and many shades of gray?
Many Shades
many choices
gray scale
wide dynamic range
low contrast
Difference between contrast and tissue harmonics?
Contrast Harmonics
created during reflection off of microbubbles
occurs only when contrast agents are present and with MIs greater than 0.1
results from nonlinear behavior of microbubbles
stronger harmonic signal
Difference between contrast and tissue harmonics?
Tissue Harmonics
created during transmission
occurs as sound propagates in tissue
results from nonlinear behavior of transmitted sound beam
weaker harmonic signal
MI, know how it is calculated?
Peak Rarefraction Pressure / √Frequency
Pulse Inversion
The positive and negative reflections are combined.
The fundamental portions are eliminated, leaving only the harmonic part of the reflection.
Designed to utilize harmonic reflection free, while eliminating distorted fundamental reflections.
Low MI: <0.1
No harmonics backscatter linear behavior higher frequency low beam strength bubble expands very little
Higher MI: 0.1-1.0
Some harmonics resonance nonlinear behavior lower frequency higher beam strength bubble expands moderately
Highest MI: > 1
Strongest harmonics bubble disruption extreme nonlinear behavior lowest frequency highest beam strength bubble expands greatly
