Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Magnetic Resonance Imaging01:24

Magnetic Resonance Imaging

9.0K
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...
9.0K
Atomic Nuclei: Magnetic Resonance01:05

Atomic Nuclei: Magnetic Resonance

1.1K
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...
1.1K
NMR Spectrometers: Resolution and Error Correction01:14

NMR Spectrometers: Resolution and Error Correction

1.0K
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...
1.0K

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Arthroscopy-Validated Diagnostic Performance of a Deep Learning Reconstruction Pipeline for Rapid 7-Minute Five-Sequence 3-T Knee MRI.

AJR. American journal of roentgenology·2026
Same author

[Distal iliotibial tract friction syndrome: MRI Characteristics].

RoFo : Fortschritte auf dem Gebiete der Rontgenstrahlen und der Nuklearmedizin·2026
Same author

Interdisciplinary consensus statements on imaging of scaphoid fractures.

European radiology·2026
Same author

Rapid Musculoskeletal MRI in 2026: Clinical Integration of Deep Learning Reconstruction.

AJR. American journal of roentgenology·2026
Same author

Optimizing Radiography Utilization: Multidisciplinary Expert Consensus Recommendations Endorsed by the Society of Academic Bone Radiologists, Society of Skeletal Radiology, American Society of Emergency Radiology, Orthopaedic Trauma Association, American Academy of Emergency Medicine, and American Rhinologic Society.

Radiology·2026
Same author

New Techniques in Musculoskeletal MRI: State of the Art.

Seminars in musculoskeletal radiology·2026

Related Experiment Video

Updated: Jan 11, 2026

Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease
09:30

Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease

Published on: December 18, 2016

20.0K

Optimized Variable Flip Angle Technique for Specific Absorption Rate Reduction in Metal Artifact Reduction Magnetic

Iman Khodarahmi, William Walter, Paul Wojack

    Investigative Radiology
    |November 18, 2025
    PubMed
    Summary

    Optimized variable refocusing flip angle (VRFA) MRI reduces specific absorption rate (SAR) and scan time for metal artifact reduction without compromising image quality. This method enhances MRI efficiency for patients with implants.

    Keywords:
    SAR reductionSEMACmetal artifact reductionvariable flip angle

    More Related Videos

    Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences
    08:19

    Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences

    Published on: May 17, 2018

    10.3K
    Author Spotlight: Using Hyperpolarized Xenon-129 MRI to Study Lung Diseases
    09:55

    Author Spotlight: Using Hyperpolarized Xenon-129 MRI to Study Lung Diseases

    Published on: January 5, 2024

    1.8K

    Related Experiment Videos

    Last Updated: Jan 11, 2026

    Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease
    09:30

    Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease

    Published on: December 18, 2016

    20.0K
    Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences
    08:19

    Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences

    Published on: May 17, 2018

    10.3K
    Author Spotlight: Using Hyperpolarized Xenon-129 MRI to Study Lung Diseases
    09:55

    Author Spotlight: Using Hyperpolarized Xenon-129 MRI to Study Lung Diseases

    Published on: January 5, 2024

    1.8K

    Area of Science:

    • Magnetic Resonance Imaging (MRI)
    • Medical Physics
    • Biomedical Engineering

    Background:

    • Metal artifact reduction MRI techniques often exceed specific absorption rate (SAR) limits due to high-bandwidth radiofrequency pulses.
    • Exceeding SAR limits leads to scan interruptions and prolonged acquisition times, impacting patient throughput and experience.
    • Standard constant refocusing flip angle (CRFA) methods may not be optimal for balancing SAR, scan time, and image quality.

    Purpose of the Study:

    • To reduce SAR and potentially scan time in metal artifact reduction MRI.
    • To evaluate an optimized variable refocusing flip angle (VRFA) scheme against the standard CRFA.
    • To maintain image quality, including artifact reduction and tissue contrast, while lowering SAR.

    Main Methods:

    • Developed three VRFA variants (VRFA1-VRFA3) to optimize tissue signal, contrast, SAR, and image blur.
    • Selected the optimal VRFA variant (VRFA3) based on phantom and volunteer studies.
    • Compared CRFA and optimal VRFA using high-bandwidth turbo-spin-echo (HBW-TSE) and compressed-sensing slice-encoding-for-metal-artifact-correction (CS-SEMAC) sequences in 23 patients with hip arthroplasty.

    Main Results:

    • No significant differences in image blur or metal artifacts were observed between CRFA and VRFA.
    • The optimal VRFA preserved significant fat-muscle and fluid-muscle contrast while reducing SAR by 23-30% and scan time by 30-33% on PD and STIR sequences.
    • Optimal VRFA was noninferior to CRFA in all quality metrics and significantly reduced SAR across all tested sequences (P ≤ 0.001).

    Conclusions:

    • Metal artifact reduction MRI using VRFA effectively reduces SAR without compromising image quality.
    • The VRFA technique allows for shorter acquisition times, particularly in HBW-TSE sequences.
    • VRFA represents a promising advancement for improving the efficiency and feasibility of MRI in patients with metallic implants.