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Related Concept Videos

Double Resonance Techniques: Overview01:12

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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.
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Related Experiment Video

Updated: Jan 4, 2026

Shaping the Amplitude and Phase of Laser Beams by Using a Phase-only Spatial Light Modulator
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Channel-combination method for phase-based |B1+| mapping techniques.

Yunyu Gao1, Jijun Han1, Yurong Zhu1

  • 1School of Biomedical Engineering, Southern Medical University, No. 1023-1063 Shatai South Road, Baiyun district, Guangzhou City, Guangdong Province 510515, China.

Magnetic Resonance Imaging
|November 1, 2019
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Summary

This study introduces a new channel combination technique for B1+ mapping using phase differences. The method improves B1+ map accuracy by reducing noise-induced errors in MRI.

Keywords:
Channel combinationMultiple receivers coilPhase noise|B(1)(+)| mapping methods

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Area of Science:

  • Magnetic Resonance Imaging (MRI)
  • Quantitative MRI techniques

Background:

  • B1+ mapping is crucial for accurate MRI quantification.
  • Phase-based B1+ mapping methods utilize phase differences between scans.
  • Noise in MRI data can affect the accuracy of phase-based B1+ mapping.

Purpose of the Study:

  • To propose a novel channel combination method for B1+ mapping.
  • To improve the accuracy of B1+ map reconstruction using phase differences.
  • To address noise-induced errors in phase-based B1+ mapping.

Main Methods:

  • Developed a channel combination method based on maximum likelihood estimation of phase differences.
  • Applied the method to Bloch-Siegert shift B1+ mapping.
  • Validated the method using simulations, phantom, and in vivo experiments at 1.5T with an 8-channel coil.
  • Compared the proposed method against the weighted averaging (WA) technique.

Main Results:

  • Simulations confirmed that phase differences can be approximated by a Gaussian distribution.
  • The proposed method demonstrated reduced B1+ calculation errors compared to the WA method.
  • Experimental results from phantom and in vivo scans validated the method's effectiveness.

Conclusions:

  • The proposed method effectively combines data from multiple receiver coils by considering phase noise distribution.
  • This approach significantly reduces B1+ reconstruction errors caused by noise.
  • The technique offers improved accuracy for quantitative MRI.