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相关概念视频

NMR Spectrometers: Resolution and Error Correction01:14

NMR Spectrometers: Resolution and Error Correction

699
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...
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NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences01:17

NMR Spectrometers: Radiofrequency Pulses and Pulse Sequences

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A pulse is a short burst of radio waves distributed over a range of frequencies that simultaneously excites all the nuclei in the sample. Upon passing a radio frequency pulse along the x-axis, the nuclei absorb energy corresponding to their Larmor frequencies and achieve resonance. This shifts the net magnetization vector from the z-axis toward the transverse plane. This angle of rotation of the magnetization vector, or the flip angle, is proportional to the duration and intensity of the pulse.
808
¹H NMR: Interpreting Distorted and Overlapping Signals01:02

¹H NMR: Interpreting Distorted and Overlapping Signals

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Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are...
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相关实验视频

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在扩散MRI中最大化每单位时间的SNR,使用多带T-Hex螺旋.

Maria Engel1, Lars Mueller1,2, André Döring1

  • 1Cardiff University Brain Research Imaging Centre (CUBRIC), Cardiff University, Cardiff, UK.

Magnetic resonance in medicine
|December 29, 2023
PubMed
概括

这项研究通过结合先进的空间编码技术来提高信号噪声比 (SNR) 效率来增强扩散MRI (dMRI). 这一突破使得更快,更高质量的微结构成像成为可能,特别有利于临床应用.

关键词:
扩散磁力共振成像 (MRI) 扩散磁场监测 磁场监测 磁场监测多频段的多频段服务.同时的多片切片.螺旋成像技术的使用.

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科学领域:

  • 磁共振成像 (MRI) 是一种磁共振成像技术.
  • 扩散型MRI (dMRI) 是一种扩散型MRI.
  • 生物医学工程 生物医学工程

背景情况:

  • 扩散MRI (dMRI) 对于表征组织微观结构至关重要.
  • 先进的dMRI模型需要高的b值和多个方向,导致漫长的扫描时间和低的信号噪声比 (SNR).
  • 提高dMRI中的SNR效率对于更广泛的临床采用和先进研究至关重要.

研究的目的:

  • 通过整合新的空间编码技术,提高dMRI中的SNR效率.
  • 通过使用高效的梯度系统,使高b值的高保真度dMRI采集成为可能.
  • 为了克服高级dMRI中长时间扫描和低SNR的局限性.

主要方法:

  • 组合螺旋读数,多频段成像和倾斜六角格 (T-Hex) 采样在3TMRI系统上.
  • 使用了一种代的cg-SENSE重建算法与NMR现场摄像头测量.
  • 将T-Hex多带方法与传统的EPI读数和blipped-CAIPIRINHA采样进行了比较.

主要成果:

  • 在体内获得高准确度的dMRI图像,b值高达40ms/μm2.2.
  • 与现有的最先进的多带扩散读取方案相比,SNR效率被证明更高.
  • 验证了临床相关的梯度性能和扩散曲解成像的方法.

结论:

  • 开发的dMRI技术显著提高了SNR的效率.
  • 这些进展促进了先进的微结构成像的广泛使用,特别是在临床环境中.
  • 这些发现为更容易获得和更强大的基于dMRI的诊断和研究铺平了道路.