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相关概念视频

Eddy Currents01:25

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An important distinction exists between the electric field induced by a changing magnetic field and the electrostatic field produced by a fixed charge distribution. Specifically, the induced electric field is nonconservative because it does not work in moving a charge over a closed path. In contrast, the electrostatic field is conservative and does no net work over a closed path. Hence, electric potential can be associated with the electrostatic field but not the induced field. The following...
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In mathematics and physics, the gradient and del operator are fundamental concepts used to describe the behavior of functions and fields in space. The gradient is a mathematical operator that gives both the magnitude and direction of the maximum spatial rate of change. Consider a person standing on a mountain. The slope of the mountain at any given point is not defined unless it is quantified in a particular direction. For this reason, a "directional derivative" is defined, which is a vector...
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Updated: Jun 30, 2025

Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors
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电流的预激发梯度为零凸优化扩散编码 (Pre-ENCODE).

Matthew J Middione1, Michael Loecher1, Xiaozhi Cao1

  • 1Department of Radiology, Stanford University, Stanford, California.

Magnetic resonance in medicine
|March 19, 2024
PubMed
概括
此摘要是机器生成的。

电流无凸优化扩散编码 (Pre-ENCODE) 的预激发梯度显著降低了扩散权重MRI中的图像扭曲. 与传统的单极和ENCODE序列相比,这种新的方法可以实现更短的回声时间.

关键词:
扩散扩散是一种扩散.旋流 旋流 流 流时间-最佳的最佳时间.

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科学领域:

  • 磁共振成像技术 磁共振成像技术
  • 扩散加权成像是一种扩散加权成像.
  • 图像扭曲纠正 图像扭曲纠正

背景情况:

  • 流是扩散权重MRI (DWI) 图像扭曲的重要来源.
  • 现有的方法,如单极 (MONO) 和ENCODE序列,在减轻这些扭曲和实现短回声时间方面存在局限性.
  • 尽量减少回声时间 (TE) 对于减少T2加权文物和改善DWI中的图像质量至关重要.

研究的目的:

  • 评估预激发梯度对流无效凸型优化扩散编码 (Pre-ENCODE) 的有效性,以减少流诱导的DWI扭曲.
  • 在回声时间和图像扭曲方面,比较Pre-ENCODE与传统MONO和ENCODE序列的性能.

主要方法:

  • 评估了包括MONO,ENCODE和Pre-ENCODE在内的扩散权重MRI序列.
  • 评估涉及模拟,幻影实验,以及在人体志愿者体内的DWI.
  • 关键指标包括最小可实现的回声时间 (TE) 和通过intravoxel信号变异估计流诱导的图像扭曲.

主要成果:

  • 在模拟中,Pre-ENCODE在各种b值和空间分辨率上始终实现了比MONO和ENCODE更短的回声时间 (TE).
  • 用Intravoxel信号变异来衡量图像扭曲,与Mono相比,Pre-ENCODE显著低于Mono,并且与ENCODE相比.
  • 在体内测量显示了类似的全球大脑明显扩散系数,但与MONO相比,Pre-ENCODE的边缘扭曲减少了.

结论:

  • 在扩散成像中,Pre-ENCODE有效地减轻了流引起的图像扭曲.
  • 预编码技术在MONO和ENCODE序列上提供了较短的回声时间 (TE) 优势.
  • 这一进步有望提高扩散权重核磁共振的准确性和可靠性.