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相关概念视频

Diffusion01:12

Diffusion

217.1K
Diffusion is the passive movement of substances down their concentration gradients—requiring no expenditure of cellular energy. Substances, such as molecules or ions, diffuse from an area of high concentration to an area of low concentration in the cytosol or across membranes. Eventually, the concentration will even out, with the substance moving randomly but causing no net change in concentration. Such a state is called dynamic equilibrium, which is essential for maintaining overall...
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Diffusion01:21

Diffusion

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Diffusion is a type of passive transport. In passive transport, a substance tends to move from an area of high concentration to an area of low concentration until the concentration is equal across the space. For example, take the diffusion of substances through the air. When someone opens a perfume bottle in a room filled with people, the perfume is at its highest concentration in the bottle and is at its lowest at the edges of the room. The perfume vapor will diffuse, or spread away, from the...
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What is an Electrochemical Gradient?01:26

What is an Electrochemical Gradient?

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Adenosine triphosphate, or ATP, is considered the primary energy source in cells. However, energy can also be stored in the electrochemical gradient of an ion across the plasma membrane, which is determined by two factors: its chemical and electrical gradients.
The chemical gradient relies on differences in the abundance of a substance on the outside versus the inside of a cell and flows from areas of high to low ion concentration. In contrast, the electrical gradient revolves around an...
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Imaging Studies I: CT and MRI01:14

Imaging Studies I: CT and MRI

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Introduction: MRI and CT scans are crucial advancements in medical imaging techniques, playing a vital role in diagnosing conditions related to the gastrointestinal (GI) system. Each scan serves distinct purposes, targets specific areas, and requires unique nursing duties.
Description of the Procedures
Computed Tomography (CT) scan:
Computed Tomography (CT) scans use X-ray technology to generate detailed images of bones, organs, and tissues. During the scan, the patient lies on a moving table...
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Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion03:48

Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion

31.2K
Although gaseous molecules travel at tremendous speeds (hundreds of meters per second), they collide with other gaseous molecules and travel in many different directions before reaching the desired target. At room temperature, a gaseous molecule will experience billions of collisions per second. The mean free path is the average distance a molecule travels between collisions. The mean free path increases with decreasing pressure; in general, the mean free path for a gaseous molecule will be...
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What are Estimates?01:06

What are Estimates?

8.2K
It isn't easy to measure a parameter such as the mean height or the mean weight of a population. So, we draw samples from the population and calculate the mean height or mean weight of the individuals in the sample. This sample data acts as a representative measure of the population parameter. These sample statistics are known as estimates. 
The estimate for the mean of a sample is denoted by ͞x, whereas the mean of the population is designated as μ. Further, parameters such...
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相关实验视频

Updated: Jan 25, 2026

Role of Diffusion MRI Tractography in Endoscopic Endonasal Skull Base Surgery
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Role of Diffusion MRI Tractography in Endoscopic Endonasal Skull Base Surgery

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空间图像梯度估计从扩散MRI资料.

Iman Aganj1, Thorsten Feiweier2, John E Kirsch1

  • 1Athinoula A. Martinos Center for Biomedical Imaging, Radiology Department, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.

Magnetic resonance in medicine
|January 24, 2026
PubMed
概括
此摘要是机器生成的。

这项研究引入了一种新方法,通过扩散MRI (dMRI) 信号来估计组织放松时间属性梯度. 这种进步允许更好地表征组织特性,而不是纤维连续性效应.

关键词:
扩散核磁共振成像 (dMRI)放松时间,放松时间.空间梯度的空间梯度刺激回声 (STE) 是一种

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Digital Spatial Profiling for Characterization of the Microenvironment in Adult-Type Diffusely Infiltrating Glioma
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Digital Spatial Profiling for Characterization of the Microenvironment in Adult-Type Diffusely Infiltrating Glioma

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Tracking the Mammary Architectural Features and Detecting Breast Cancer with Magnetic Resonance Diffusion Tensor Imaging
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相关实验视频

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Role of Diffusion MRI Tractography in Endoscopic Endonasal Skull Base Surgery

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Digital Spatial Profiling for Characterization of the Microenvironment in Adult-Type Diffusely Infiltrating Glioma
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科学领域:

  • 生物医学成像技术 生物医学成像技术
  • 神经成像是一种神经成像.
  • 扩散磁力共振成像物理学

背景情况:

  • 扩散MRI (dMRI) 中的水分子与不同的组织放松时间特性相互作用.
  • 这一关键因素在历史上在dMRI分析中未得到充分利用.
  • 考虑到放松时间的变化,可以揭示有关组织微观结构的新信息.

研究的目的:

  • 模拟不同组织放松时间特性对dMRI信号的影响.
  • 从dMRI数据开发一种估计放松时间特性梯度的方法.
  • 研究dMRI信号与空间图像梯度之间的关系.

主要方法:

  • 获得了一种新的数学关系,将dMRI扩散信号与空间图像梯度联系起来.
  • 在三个不同的人类大脑dMRI数据集上验证了该方法,包括公共和内部数据.
  • 量化了纤维连续性的影响,作为潜在的混因素.

主要成果:

  • 从dMRI信号估计的空间图像梯度与黄金标准梯度有显著的相关性.
  • 观察到的效应在统计学上与纤维连续性的影响不同.
  • 这些发现在所有测试数据集中都是一致的.

结论:

  • 这项研究证实了 voxel 内dMRI信号与图像梯度之间的假设关系.
  • 这种关系独立于光纤连续性的混效应.
  • 开发的方法提供了一种使用dMRI探测组织特性的新方法.