Particle Magnetic Resonance Research Articles

Development and validation of an MRI-based method for 3D particle concentration measurement

A novel method, denoted MRP (short for Magnetic Resonance Particle concentration), was developed to obtain 3D volume fraction measurements for a dispersed particulate phase in turbulent water flows using Magnetic Resonance Imaging (MRI). MRI images taken near a single stainless steel particle suspended in agarose gel showed good agreement with the analytical solution for the disturbance to a uniform magnetic field induced by an immersed sphere. For a random distribution of particles, a linear relationship between the MRI signal decay rate (R2*) and particle volume fraction (ϕv) has previously been predicted in the MRI literature. This relationship was investigated for various types of particles suspended in agarose gel vials. Good agreement with theory was observed for particles with a high magnetic susceptibility difference from water. R2* was also measured in a square channel flow containing a uniform distribution of titanium particles at two fully turbulent Reynolds numbers. Experimental results again agreed well with theory in the majority of the channel for both Reynolds numbers studied. Data from this flow were used to examine the expected SNR and dynamic range for MRP in future experiments. Some discrepancy was observed near the entry region of the channel, with possible explanations including inflowing fluid and large-scale flow structure effects behind the channel’s mixing pin array. Finally, the new method was used to measure the 3D concentration distribution for a streak of titanium particles injected into a turbulent square channel flow with angled ribs. The transport of the streak was analyzed quantitatively, and a minor asymmetry in the channel geometry was shown to have important implications for the mean transport of the particle streak.

Apolipoprotein B and Nuclear Magnetic Resonance Particle Number

To the Editor: In the recent special report on the assessment of apolipoprotein B (apoB)1 and nuclear magnetic resonance particle number (1), the authors recommended that measurement of particle number be incorporated into the guidelines for the assessment of cardiovascular disease (CVD) risk. However, the literature reviewed provides no basis for this recommendation. Searching the literature using the key terms apo B and LDL-P (LDL particle number) and the name …

5291422 Broadband instrument for nondestructive measurement of material properties

An instrument for measuring the properties of materials. This nondestructive, noncontacting instrument detects electromagnetic radiation from the materials across a wide range of the electromagnetic spectrum, and combines these diverse data so as to derive the material property values desired. In particular, the properties detectable through particle magnetic resonance, spectroscopy of light in the infrared-visible-ultraviolet range, and detection of x-ray and gamma ray radiation may be included in the instrument. Sensors detect each wavelength band of electromagnetic radiation, and data from all of these sensors is merged in a central data processor to evaluate the material properties of interest.