Related Experiment Video

Updated: Jan 22, 2026

Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System
10:36

Prescribed 3-D Direct Writing of Suspended Micron/Sub-micron Scale Fiber Structures via a Robotic Dispensing System

Published on: June 12, 2015

8.4K

Effects of motion on MRI signal decay from micron-scale particles

Daniel D Borup1, Christopher J Elkins1, John K Eaton1

  • 1Department of Mechanical Engineering, 488 Escondido Mall, Building 500, Stanford, CA 94305, USA.

Journal of Magnetic Resonance (San Diego, Calif. : 1997)
|July 9, 2019
PubMed

Insights

Transverse decay rate (R2*) mapping, used for iron overload measurement, showed discrepancies in turbulent flow particle tracking. Relative particle-fluid motion was identified as the primary cause of these R2* measurement errors.

Area of Science:

  • Magnetic Resonance Imaging (MRI)
  • Fluid Dynamics
  • Biophysics

Background:

  • Transverse decay rate (R2*) mapping is a standard technique for quantifying iron concentration in biological tissues.
  • Recent applications of R2* mapping to measure particle distribution in turbulent flows revealed discrepancies with theoretical predictions.
  • Understanding these discrepancies is crucial for accurate particle concentration measurements in both medical and engineering contexts.

Purpose of the Study:

  • To investigate three flow-related mechanisms causing discrepancies between measured and theoretically expected R2* values in particle-laden turbulent flows.
  • To differentiate the signal-time curve and R2* effects of relative particle-fluid motion, turbulent preferential concentration, and enhanced proton dispersion.
  • To validate simulation findings against experimental data from a square channel flow.

Main Methods:

  • Computational simulations were employed to model the effects of relative particle-fluid motion and turbulent preferential concentration.
  • Existing MRI relaxation theory was utilized to examine the impact of turbulence-induced enhanced proton dispersion.
  • Experimental data from a square channel flow were used for comparison and validation.

Main Results:

  • Each investigated flow phenomenon (relative motion, preferential concentration, proton dispersion) exhibited distinct effects on the MRI signal-time curve and extracted R2* values.
  • Comparison with experimental data indicated that relative particle-fluid motion was the most significant contributor to the observed R2* discrepancies.
  • The study successfully differentiated the MRI signal characteristics associated with each flow mechanism.

Conclusions:

  • Relative particle-fluid motion is identified as the primary cause of discrepancies in previous R2* mapping experiments of particle-laden turbulent flows.
  • All three investigated mechanisms may concurrently influence MRI signal behavior in diverse medical and non-medical applications.
  • The distinct MRI signal signatures of these mechanisms offer potential for their future identification directly from MRI data.
Keywords:
FlowMagnetic resonance imagingParticlesSignal decayTurbulence

More Related Videos

Fabrication of Magnetic Platforms for Micron-Scale Organization of Interconnected Neurons09:54

Fabrication of Magnetic Platforms for Micron-Scale Organization of Interconnected Neurons

Published on: July 14, 2021

5.2K
Micron-scale Resolution Optical Tomography of Entire Mouse Brains with Confocal Light Sheet Microscopy09:49

Micron-scale Resolution Optical Tomography of Entire Mouse Brains with Confocal Light Sheet Microscopy

Published on: October 8, 2013

17.1K

Related Concept Videos

Radioactive Decay and Radiometric Dating02:48

Radioactive Decay and Radiometric Dating

Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. The number of disintegrations per unit time is called the activity (A), which is directly proportional to the number of nuclei in the sample. The decay constant (λ) is an average probability of decay per nucleus in unit time.
36.9K
Motion Of A Charged Particle In A Magnetic Field01:22

Motion Of A Charged Particle In A Magnetic Field

A charged particle experiences a force when moving through a magnetic field. Consider the field to be uniform and the charged particle to move perpendicular to it. If the field is in a vacuum, the magnetic field is the dominant factor determining the motion. Since the magnetic force is perpendicular to the direction of motion, a charged particle follows a curved path. The particle continues to follow this curved path until it forms a complete circle. Another way to look at this is that the...
6.8K
Nonsense-mediated mRNA Decay02:27

Nonsense-mediated mRNA Decay

The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
Usually, Upf3 binds to an Exon Junction Complex (EJC) at mRNA splice sites. If a ribosome fully translates the mRNA,...
11.7K
Nonsense-mediated mRNA Decay02:27

Nonsense-mediated mRNA Decay

3.3K
Interference and Decay01:16

Interference and Decay

Forgetting is a complex cognitive phenomenon influenced by several factors, among which interference and decay are particularly prominent. These processes explain why individuals often struggle to retrieve specific information from memory, leading to lapses in recall that can be observed in everyday situations.
Interference occurs when competing memories hinder the retrieval of particular information. It can be classified into two types: proactive and retroactive interference. Proactive...
432
Factors Affecting Dissolution: Particle Size and Effective Surface Area01:23

Factors Affecting Dissolution: Particle Size and Effective Surface Area

Dissolution kinetics, an essential aspect of oral drug delivery, is significantly influenced by the drug's particle size. According to the Noyes-Whitney dissolution model, the dissolution rate correlates directly with the drug's surface area. The larger the surface area, the higher the drug's solubility in water, leading to a faster drug dissolution rate. Reducing particle size increases the effective surface area, enhancing the dissolution process. Micronization and nanosizing are...
1.6K