Related Experiment Video
Updated: Jul 7, 2026
08:55
High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy
Published on: October 9, 2020
Spin-Inversion Imaging: A Technique for NMR Imaging under Magnetic Fields with High Field Nonuniformities
IEEE Transactions on Medical Imaging
|January 1, 1987
Summary
Spin inversion (SI) imaging removes magnetic field nonuniformity effects in NMR imaging. This technique offers robust imaging independent of field variations and chemical shifts, ideal for applications like head scanning.
Area of Science:
- Magnetic Resonance Imaging
- Medical Physics
- Nuclear Magnetic Resonance
Background:
- Nonuniform magnetic fields in NMR imaging introduce artifacts.
- Field inhomogeneities and chemical shifts degrade image quality and accuracy.
Purpose of the Study:
- To introduce and describe spin inversion (SI) imaging.
- To address challenges posed by high magnetic field nonuniformity in NMR.
Main Methods:
- Employing 180-degree radiofrequency (RF) pulses between Free Induction Decay (FID) sampling.
- Developing methods to reduce peak RF power requirements.
- Utilizing computer simulations to demonstrate the technique's efficacy.
Main Results:
- SI imaging effectively removes artifacts caused by main-field nonuniformities.
- Generated images show independence from field variations and chemical shifts.
- The method has relaxed requirements on gradient pulse shapes.
Conclusions:
- Spin inversion imaging is a viable technique for NMR imaging in highly nonuniform magnetic fields.
- The method is particularly suitable for small-volume imaging, such as head scans.
- SI imaging enhances image robustness and reduces dependency on field homogeneity.
Related Concept Videos
01:03Atomic Nuclei: Nuclear Spin State Overview
NMR-active nuclei have energy levels called 'spin states' that are associated with the orientations of their nuclear magnetic moments. In the absence of a magnetic field, the nuclear magnetic moments are randomly oriented, and the spin states are degenerate. When an external magnetic field is applied, the spin states have only 2 + 1 orientations available to them. A proton with = ½ has two available orientations. Similarly, for a quadrupolar nucleus with a nuclear spin value of one, the...
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...
01:08NMR Spectroscopy: Spin–Spin Coupling
The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
01:24Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) is a noninvasive medical imaging technique based on a phenomenon of nuclear physics discovered in the 1930s, in which matter exposed to magnetic fields and radio waves was found to emit radio signals. In 1970, a physician and researcher named Raymond Damadian noticed that malignant (cancerous) tissue gave off different signals than normal body tissue. He applied for a patent for the first MRI scanning device in clinical use by the early 1980s. The early MRI...
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
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...