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

Aliasing01:18

Aliasing

945
Accurate signal sampling and reconstruction are crucial in various signal-processing applications. A time-domain signal's spectrum can be revealed using its Fourier transform. When this signal is sampled at a specific frequency, it results in multiple scaled replicas of the original spectrum in the frequency domain. The spacing of these replicas is determined by the sampling frequency.
If the sampling frequency is below the Nyquist rate, these replicas overlap, preventing the original...
945
Reconstruction of Signal using Interpolation01:10

Reconstruction of Signal using Interpolation

920
Signal processing techniques are essential for accurately converting continuous signals to digital formats and vice versa. When a continuous signal is sampled with a period T, the resulting sampled signal exhibits replicas of the original spectrum in the frequency domain, spaced at intervals equal to the sampling frequency. To handle this sampled signal, a zero-order hold method can be applied, which creates a piecewise constant signal by retaining each sample's value until the next...
920
Downsampling01:20

Downsampling

872
When considering a sampled sequence with zero values between sampling instants, one can replace it by taking every N-th value of the sequence. At these integer multiples of N, the original and sampled sequences coincide. This process, known as decimation, involves extracting every N-th sample from a sequence, thereby creating a more efficient sequence.
The Fourier transform of the decimated sequence reveals a combination of scaled and shifted versions of the original spectrum. This...
872
Upsampling01:22

Upsampling

745
Managing signal sampling rates is essential in digital signal processing to maintain signal integrity. A decimated signal, characterized by a reduced frequency range due to its lower sampling rate, can be upsampled by inserting zeros between each sample. This upsampling process expands the original spectrum and introduces repeated spectral replicas at intervals dictated by the new Nyquist frequency. To refine this zero-inserted sequence, it is passed through a lowpass filter with a cutoff...
745
Biasing of Metal-Semiconductor Junctions01:27

Biasing of Metal-Semiconductor Junctions

907
Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...
907

You might also read

Related Articles

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

Sort by
Same author

Cost-utility of focused ultrasound compared to radiotherapy for Dutch patients with uncomplicated non-spinal bone metastases.

The European journal of health economics : HEPAC : health economics in prevention and care·2025
Same author

Patient Education and Communication in Palliative Radiotherapy: A Narrative Review.

Cancers·2025
Same author

Trident: Three-dimensional ray tracing for modeling high intensity focused ultrasound ablation.

The Journal of the Acoustical Society of America·2025
Same author

Interrater Agreement in Assessment of Eligibility for Magnetic Resonance-Guided High-Intensity Focused Ultrasound of Patients with Painful Bone Metastases.

Journal of vascular and interventional radiology : JVIR·2025
Same author

Mechanical HIFU and immune checkpoint inhibition: toward clinical implementation.

International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group·2024
Same author

Quantitative MRI assessment of joint effusion using T2-relaxometry at 3 Tesla: a feasibility and reproducibility study.

Skeletal radiology·2024

Related Experiment Video

Updated: May 3, 2026

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

9.7K

Ripple artifact reduction using slice overlap in slice encoding for metal artifact correction.

J Chiel den Harder1, Gert H van Yperen2, Ulrike A Blume3

  • 1Medical Physics Department, Reinier de Graaf Groep, Delft, the Netherlands.

Magnetic Resonance in Medicine
|February 4, 2014
PubMed
Summary
This summary is machine-generated.

Ripple artifacts in metal artifact reduction (MAR) techniques like slice encoding for metal artifact correction (SEMAC) can be reduced using slice overlap. This method improves image quality near metal implants, despite a slight increase in scan time.

Keywords:
MRISEMACimplantmetalpile-up artifactripple artifact

More Related Videos

Author Spotlight: Unraveling Seizure Dynamics and Novel Therapeutics for Status Epilepticus Using CMOS High-Density Microelectrode Array Systems
06:28

Author Spotlight: Unraveling Seizure Dynamics and Novel Therapeutics for Status Epilepticus Using CMOS High-Density Microelectrode Array Systems

Published on: September 27, 2024

2.7K
Equipment Setup and Artifact Removal for Simultaneous Electroencephalogram and Functional Magnetic Resonance Imaging for Clinical Review in Epilepsy
10:23

Equipment Setup and Artifact Removal for Simultaneous Electroencephalogram and Functional Magnetic Resonance Imaging for Clinical Review in Epilepsy

Published on: June 23, 2023

3.4K

Related Experiment Videos

Last Updated: May 3, 2026

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

9.7K
Author Spotlight: Unraveling Seizure Dynamics and Novel Therapeutics for Status Epilepticus Using CMOS High-Density Microelectrode Array Systems
06:28

Author Spotlight: Unraveling Seizure Dynamics and Novel Therapeutics for Status Epilepticus Using CMOS High-Density Microelectrode Array Systems

Published on: September 27, 2024

2.7K
Equipment Setup and Artifact Removal for Simultaneous Electroencephalogram and Functional Magnetic Resonance Imaging for Clinical Review in Epilepsy
10:23

Equipment Setup and Artifact Removal for Simultaneous Electroencephalogram and Functional Magnetic Resonance Imaging for Clinical Review in Epilepsy

Published on: June 23, 2023

3.4K

Area of Science:

  • Medical Imaging
  • Physics

Background:

  • Multispectral imaging (MSI) is effective at reducing metal artifacts.
  • Gradient selection techniques, such as slice encoding for metal artifact correction (SEMAC), can leave residual ripple artifacts.

Purpose of the Study:

  • To analyze the cause of ripple artifacts in gradient selection-based MSI.
  • To investigate slice overlap as a method to reduce these artifacts.

Main Methods:

  • Theoretical analysis of the ripple artifact.
  • Implementation of slice overlap by adjusting the selection gradient to widen the slice profile.
  • Validation through time-domain simulations and phantom experiments.

Main Results:

  • Ripple artifacts are caused by signal displacement in areas with deviating B0 fields, both in-plane and through-plane.
  • Slice overlap effectively reduces these artifacts, as confirmed by simulations and phantom studies.
  • The efficacy was demonstrated in the context of metal implants.

Conclusions:

  • The ripple artifact is a significant limitation in gradient selection-based MSI techniques.
  • Slice overlap is a viable solution to mitigate ripple artifacts, enhancing image quality near metal implants.
  • This solution comes with a minor trade-off in scan time.