Related Experiment Video
Updated: Jan 20, 2026
05:56
Author Spotlight: Enhancing Diagnostic Strategies and Biomarker Development for Comprehensive Lung Function Analysis
Published on: August 9, 2024
2.4K
Noise estimation for the velocity in MRI phase-contrast
Pablo Irarrazaval1, Ali Dehghan Firoozabadi2, Sergio Uribe3
1Electrical Engineering Department, Pontificia Universidad Catolica de Chile, Santiago 7820436, Chile; Biomedical Imaging Center, Pontificia Universidad Catolica de Chile, Santiago 7820436, Chile; Institute for Biological and Medical Engineering, Pontificia Universidad Catolica de Chile, Santiago 7820436, Chile; Millennium Nucleus for Cardiovascular Magnetic Resonance, Santiago, Chile.
Magnetic Resonance Imaging
|August 27, 2019
Summary
This study estimates the precision of Magnetic Resonance Imaging (MRI) phase-contrast velocity measurements. Understanding the velocity
Area of Science:
- Medical Imaging
- Biophysics
Background:
- Phase-contrast MRI is crucial for velocity measurement.
- Accurate interpretation of derived parameters depends on velocity precision.
Purpose of the Study:
- To estimate the precision and statistical variability of velocity measurements from MRI phase-contrast.
- To develop a method for optimal combination of data from multiple coils.
Main Methods:
- Derived the probability density function (PDF) of velocity from the phase signal's PDF using auto-convolution.
- Analyzed velocity distribution for high and low Signal-to-Noise Ratio (SNR) voxels.
- Investigated optimal coil combination strategies based on coil-specific PDFs.
Main Results:
- Velocity distribution approximates Gaussian for high SNR, but is between Gaussian and uniform for low SNR.
- Empirical validation confirmed the theoretical distribution findings.
- Optimal coil combination significantly reduces global velocity variability compared to Weighted Mean or SENSE (R=1).
Conclusions:
- The derived PDF accurately characterizes velocity precision in phase-contrast MRI.
- The method provides a framework for robust velocity estimation across varying SNR.
- Optimal coil combination enhances the reliability of MRI-based velocity measurements.
Related Concept Videos
01:26Phase Contrast and Differential Interference Contrast Microscopy
12.1K
Phase-Contrast Microscopes
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
12.1K
01:12Average Velocity
22.4K
To calculate the other physical quantities in kinematics, we must introduce the time variable. The time variable allows us not only to state the position of the object during its motion, but also how fast it is moving. The speed at which an object is moving is given by the rate at which the position changes with time. For each position xi, we assign a particular time ti. If the details of the motion at each instant are not important, the rate is usually expressed as the average velocity. This...
22.4K
01:10Instantaneous Velocity - II
12.2K
Instantaneous velocity is the quantity that measures how fast an object is moving along its path. In other words, the instantaneous velocity of an object is the limit of the average velocity as the elapsed time approaches zero, or the derivative of displacement with respect to time. Like average velocity, the instantaneous velocity is a vector with the dimensions of length per unit time. Instantaneous velocity can have both positive and negative values. The instantaneous velocity can be...
12.2K
01:26Escape Velocity
8.3K
The escape velocity of an object is defined as the minimum initial velocity that it requires to escape the surface of another object to which it is gravitationally bound and never to return. For example, what would be the minimum velocity at which a satellite should be launched from the Earth's surface such that it just escapes the Earth's gravitational field?
To calculate the escape velocity, it is assumed that no energy is lost to any frictional forces. In practice, a satellite...
To calculate the escape velocity, it is assumed that no energy is lost to any frictional forces. In practice, a satellite...
8.3K
01:20Velocity Potential
706
In steady, incompressible flow through a long, straight pipe with a uniform cross-section, the flow in the central region (far from the pipe walls) is irrotational. This irrotational nature means that fluid particles do not rotate around their axes, and a scalar function called the velocity potential, represented by ϕ, can be used to describe their movement. In irrotational flows, the velocity field V is defined as the gradient of the velocity potential:
706
01:06What are Estimates?
8.2K
It isn't easy to measure a parameter such as the mean height or the mean weight of a population. So, we draw samples from the population and calculate the mean height or mean weight of the individuals in the sample. This sample data acts as a representative measure of the population parameter. These sample statistics are known as estimates.
The estimate for the mean of a sample is denoted by ͞x, whereas the mean of the population is designated as μ. Further, parameters such...
The estimate for the mean of a sample is denoted by ͞x, whereas the mean of the population is designated as μ. Further, parameters such...
8.2K