DISPLAY MODES & 2D IMAGING
In A-mode, the height of the spike on the display represents this.
What is the amplitude (strength) of the returning echo?
This is the number of frames displayed per second and is the most important parameter in real-time imaging.
What is frame rate?
This type of display uses only two shades: black and white.
What is a bistable display?
This term refers to the study of blood moving through the circulatory system.
What is hemodynamics?
This type of Doppler uses two crystals (one continuously transmitting, one continuously receiving) and can measure very high velocities without aliasing.
What is continuous wave (CW) Doppler?
This display mode uses brightness of dots to represent reflection strength and is the standard for anatomical imaging.
What is B-mode (Brightness Mode)?
This type of resolution, determined by frame rate, refers to the accuracy in positioning moving structures from instant to instant.
What is temporal resolution?
This is the smallest building block of a digital picture, short for "picture element.
What is a pixel?
This type of flow is characterized by organized, parallel layers and is associated with normal physiology, with a Reynolds number less than 1500.
What is laminar flow?
This is the formula for the Nyquist limit.
What is PRF / 2?
M-mode is named for its ability to show this, and its primary uses include assessing cardiac wall motion and fetal heart rate.
What is motion?
Imaging depth and frame rate share this type of relationship.
What is an inverse relationship?
This receiver operation reduces the dynamic range of a signal so it can fit the display's capabilities, without changing which signals are largest and smallest.
What is compression (or log compression)
This principle states that within a stenosis, velocity increases as pressure decreases.
What is Bernoulli's principle?
This Doppler technique processes the amplitude of the signal, making it more sensitive to low flow rates but susceptible to flash artifact.
What is power Doppler?
This term refers to the thickness of the imaging plane and is also known as elevational resolution.
What is slice thickness?
This term describes the ability to perform simultaneous anatomical (B-mode) imaging and Doppler.
What is duplex imaging?
This emerging technology creates images based on the mechanical properties (stiffness) of tissues rather than their acoustic reflectivity.
What is elastography?
What is elastography?
In a standing patient, hydrostatic pressure at the level of the heart is zero, but it becomes this below the heart.
Question: What is positive (+)
Increasing this control is the most effective way to reduce aliasing in a color Doppler image, though it decreases sensitivity to slow flow.
What is the velocity scale (or PRF)?
This technique varies the strength of the electrical spike to each element to reduce grating lobe artifacts.
What is apodization?
High line density improves lateral resolution but has this negative effect on temporal resolution due to the increased number of pulses required.
What is it reduces frame rate?
This imaging technique combines sonographic information from different imaging angles into a single image to reduce speckle and shadowing artifacts.
What is spatial compounding?
This form of energy is lost when blood slides against vessel walls and is converted to heat.
What is frictional loss?
This complex artifact appears on spectral Doppler as low-frequency, high-amplitude signals near the baseline, caused by slowly moving vessel walls.
What is clutter (or wall thump)?