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相关概念视频

Magnetic Susceptibility and Permeability01:31

Magnetic Susceptibility and Permeability

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In linear magnetic materials, like paramagnets and diamagnets, magnetization is proportional to the magnetic field intensity. The constant of proportionality, a dimensionless number, is called magnetic susceptibility. The value of the susceptibility depends on the type of material.
When diamagnetic materials are placed under an external magnetic field, the moments opposite to the field are induced. Hence, the susceptibility for diamagnets has a minimal negative value of 10-5–10-6. Since...
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Magnetic Resonance Imaging01:24

Magnetic Resonance Imaging

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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...
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Potential Due to a Magnetized Object01:24

Potential Due to a Magnetized Object

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Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
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Diamagnetism01:26

Diamagnetism

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Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets....
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Atomic Nuclei: Magnetic Resonance01:05

Atomic Nuclei: Magnetic Resonance

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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...
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相关实验视频

Updated: May 9, 2025

Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
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在磁性不均质组织中进行定量敏感度映射.

Thomas Jochmann1,2, Fahad Salman2,3, Michael G Dwyer2,4

  • 1Institute of Biomedical Engineering and Informatics, Department of Computer Science and Automation, Technische Universität Ilmenau, Ilmenau, Germany.

Magnetic resonance in medicine
|May 2, 2025
PubMed
概括

深度学习 (DEEPOLE) 是一种新的深度学习方法,通过结合非双极拉莫尔频率转移来增强定量敏感度映射 (QSM). 这提高了准确性,并减少了脑成像中的工件,有利于研究神经疾病.

关键词:
化学交换 化学交换 化学交换宏观的非双极性 拉莫尔频率变化微观结构的微观结构阶段对比相位对比的相位对比.定量敏感性映射测绘 定量敏感性映射

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科学领域:

  • 医疗成像医学成像
  • 神经成像是一种神经成像.
  • 计算生物学 计算生物学

背景情况:

  • 传统的定量敏感度映射 (QSM) 方法利用简化的物理模型,导致生物组织的工件和不准确性,由于假设的同位素和同质性质.
  • 准确的敏感性测绘对于了解各种神经疾病至关重要.

研究的目的:

  • 开发和评估基于深度学习的QSM方法DEEPOLE,该方法包含宏观非双极的Larmor频率转移.
  • 与传统的QSM算法相比,提高易感度图的质量和准确性.

主要方法:

  • DEEPOLE将QUASAR模型集成到一个深层卷积神经网络中,以捕获被忽视的频率贡献.
  • 该方法在合成数据上进行了训练,并使用数字大脑模型和体内人类大脑数据对已建立的QSM算法 (深度学习QSM,QUASAR,MEDI,FANSI,SDI) 进行了验证.

主要成果:

  • 在数字大脑模型中,DEEPOLE在传统QSM方法中表现出优越的性能,产生更少的文物和更高的定量准确性,特别是在微观结构效应方面.
  • 在体内,DEEPOLE产生了更具解剖学一致性的易感性地图,减少了不均性和条纹等人工物,并改善了深灰色和白色物质的易感性估计.

结论:

  • 通过DEEPOLE将宏观非双极的Larmor频率转移纳入其中,可以显著提高易感性地图的质量和准确性.
  • 这一进步提高了敏感性测量的可靠性,特别是对于神经退行性和脱髓性疾病,这些疾病的贡献很大.