Hemodynamics
This is the study of blood moving through the circulatory system
What is hemodynamics
The ideal maximum Doppler angle for obtaining an accurate velocity measurement.
What is 60 degrees?
This is the most common reason for a complete absence of color in a vessel when using color Doppler, even when flow is present.
What is perpendicular incidence (or a 90-degree angle)?
The smallest building block of a digital picture, whose density determines image detail and spatial resolution
What is a pixel?
The type of blood flow characterized by chaotic patterns in many directions and at many speeds, often associated with cardiovascular pathology
What is turbulent flow?
This type of flow, with a Reynolds number less than 1500, is characterized by organized, parallel layers and is associated with normal physiology.
What is laminar flow
This pulsed-wave artifact occurs when the Doppler shift frequency exceeds the Nyquist limit.
What is aliasing?
The appearance of "color confetti" throughout the color box is a result of setting this control too high.
What is color gain?
This type of image processing that is performed on data after it is retrieved from the scan converter.
What is postprocessing?
These encapsulated gas bubbles are used as contrast agents, resonating nonlinearly to produce strong harmonic signals.
What are microbubbles?
The principle that describes how, within a stenosis, an increase in kinetic energy leads to a decrease in pressure energy.
What is Bernoulli's Principle
This Doppler mode uses two crystals, has no backing material, and can measure very high velocities without aliasing, but suffers from range ambiguity
What is Continuous Wave (CW) Doppler?
The most effective way to reduce aliasing in a color Doppler image is to increase this control.
What is the velocity scale (or PRF)?
The unit, in decibels, used to report the range of signals an ultrasound system can accurately process, from the smallest to the largest.
What is dynamic range?
The technique that combines sonographic information from different imaging angles into a single image to reduce speckle and shadowing artifacts
What is spatial compounding?
In a standing individual, this is the hydrostatic pressure value at a point below the level of the heart.
What is positive (+
This type of Doppler processes the amplitude of the signal, making it non-directional and highly sensitive to low flow rates, but also very susceptible to flash artifact.
What is Power Doppler?
This filter selectively eliminates low-frequency Doppler shifts from slowly moving structures like vessel walls.
What is the wall filter?
This technique creates images based on the mechanical properties (stiffness) of tissues, not their acoustic reflectivity
What is elastography?
The pressure exerted by the weight of blood pressing on the vessel walls, which is zero everywhere when a patient is supine.
What is hydrostatic pressure?
During this phase of respiration, the diaphragm moves downwards, creating positive pressure in the abdomen that compresses the IVC and decreases venous flow from the lower extremities.
What is inspiration (or breathing in)
The signal processing technique used in spectral Doppler to break down the complex signal into its individual frequency components.Question:
What is Fast Fourier Transform (FFT)?
On a color map, true flow reversal is indicated by a pattern of these three colors next to each other.
What are red, black, and blue?
The set of communication protocols that allows imaging systems and PACS to share information on a network.
What is DICOM?
The three forms of energy associated with blood in the circulatory system.
What are kinetic, pressure, and gravitational energy?
What are kinetic, pressure, and gravitational energy?