Related Experiment Video
Updated: Jun 6, 2026
09:30
Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease
Published on: December 18, 2016
Multiple-stepped Zeeman field offset method applied in acquiring enhanced resolution spin-echo electron paramagnetic
Payam Seifi1, Boris Epel, Colin Mailer
1Department of Radiation and Cellular Oncology, Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, Illinois 60637, USA.
Medical Physics
|November 25, 2010
Summary
Electron paramagnetic resonance (EPR) imaging offers oxygen distribution data. A new multi-B method enhances spatial resolution and image quality in electron spin echo (ESE) imaging by overcoming bandwidth limitations.
Area of Science:
- Biomedical Imaging
- Magnetic Resonance Spectroscopy
- Oxygen Sensing
Background:
- Electron paramagnetic resonance (EPR) imaging provides quantitative in vivo oxygen distribution.
- Electron spin echo (ESE) imaging is a time-domain EPR technique with potential for improved imaging.
- Limited acquisition frequency bandwidth in ESE imaging restricts magnetic field gradients and spatial resolution.
Purpose of the Study:
- To improve spatial resolution in ESE imaging by extending the effective frequency bandwidth.
- To develop a method for acquiring higher quality EPR images by overcoming instrumental limitations.
Main Methods:
- A multi-B scheme was employed, acquiring projections at multiple Zeeman magnetic field offsets.
- Data from field offset steps were combined and normalized to restore complete projections.
- A multipurpose pulse EPR imager and phantoms with OX063H spin probe were utilized.
Main Results:
- The multi-B method yielded enhanced spatial resolution in phantom images compared to conventional ESE.
- Multi-B images demonstrated superior T2 resolution in a high spatial-resolution regime.
- Image artifacts common in high-gradient single-B ESE images were significantly reduced.
Conclusions:
- The multi-B method enhances spatial resolution and overall image quality in ESE imaging.
- This technique is less susceptible to instrumental limitations with larger gradient fields.
- The multi-B method improves ESE imaging without requiring hardware modifications.
Related Concept Videos
01:12Double Resonance Techniques: Overview
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...
01:14NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...
01:05Atomic Nuclei: Magnetic Resonance
The number of nuclear spins aligned in the lower energy state is slightly greater than those in the higher energy state. In the presence of an external magnetic field, as the spins precess at the Larmor frequency, the excess population results in a net magnetization oriented along the z axis. When a pulse or a short burst of radio waves at the Larmor frequency is applied along the x axis, the coupling of frequencies causes resonance and flips the nuclear spins of the excess population from the...
01:17NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences
A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...