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相关概念视频

Irrotational Flow01:28

Irrotational Flow

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Irrotational flow is characterized by fluid motion where particles do not rotate around their axes, resulting in zero vorticity. For a flow to be irrotational, the curl of the velocity field must be zero. This imposes specific conditions on velocity gradients. For instance, to maintain zero rotation about the z-axis, the gradient condition:
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Rapidly Varying Flow01:24

Rapidly Varying Flow

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Rapidly varying flow (RVF) in open channels is characterized by abrupt changes in flow depth over a short distance, with the rate of depth change relative to distance often approaching unity. These flows are inherently complex due to their transient and multi-dimensional nature, making exact analysis difficult. However, approximate solutions using simplified models provide valuable insights into their behavior.Key Features of Rapidly Varying FlowRVF is commonly observed in scenarios involving...
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Divergence and Curl of Magnetic Field01:26

Divergence and Curl of Magnetic Field

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The magnetic field due to a volume current distribution given by the Biot–Savart Law can be expressed as follows:
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Curvilinear Motion: Rectangular Components01:23

Curvilinear Motion: Rectangular Components

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Curvilinear motion characterizes the movement of a particle or object along a curved path, notably evident when envisioning a car navigating a winding road. If the car starts at point A, its position vector is established within a fixed frame of reference, where the ratio of the position vector to its magnitude signifies the unit vector pointing in the position vector's direction.
As the car advances, its position evolves over time. Quantifying the car's velocity involves computing the...
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Transformation of Plane Strain01:12

Transformation of Plane Strain

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When analyzing elongated structures like bars subjected to uniformly distributed loads, it is essential to understand the transformation of plane strain when coordinate axes are rotated. This transformation helps to assess how material deformation characteristics vary with orientation, which is crucial in materials science and structural engineering.
Under plane strain conditions, typical for members where one dimension significantly exceeds the others, deformations and resultant strains are...
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Region of Convergence of Laplace Tarnsform01:20

Region of Convergence of Laplace Tarnsform

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The Region of Convergence (ROC) is a fundamental concept in signal processing and system analysis, particularly associated with the Laplace transform. The ROC represents an area in the complex plane where the Laplace transform of a given signal converges, determining the transform's applicability and utility.
Consider a decaying exponential signal that begins at a specific time. When deriving its Laplace transform, the time-domain variable is replaced with a complex variable. This...
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Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
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螺旋流入的MRA具有滑动切片局部化的二次编码.

Dinghui Wang1, Guruprasad Krishnamoorthy1,2, Melvyn B Ooi2

  • 1Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.

Magnetic resonance in medicine
|July 7, 2023
PubMed
概括

这项研究引入了一种新的螺旋技术,用于更快的磁共振血管造影 (MRA),并提高了信号与噪声 (SNR) 和对比与噪声 (CNR) 的效率. 这种先进的方法提高了血管可视化的成像速度和清晰度.

科学领域:

  • 磁共振成像 (MRI) 是一种磁共振成像技术.
  • 医学成像技术 医学成像技术
  • 血管成像 血管成像

背景情况:

  • 传统的磁共振血管学 (MRA) 技术可能受扫描时间和图像质量限制.
  • 改善信号与噪声比 (SNR) 和对比与噪声比 (CNR) 对于准确的血管评估至关重要.

研究的目的:

  • 开发和评估一种2D/3D混合输入MRA技术,将局部四进制 (LQ) 编码与滑动切片螺旋采集相结合.
  • 为了提高扫描速度,同时保持MRA的高SNR和CNR效率.

主要方法:

  • 实现了滑动切片螺旋获取与局部二次 (LQ) 编码相结合.
  • 在健康志愿者中获得了威利斯圆圈和动脉分叉的输入MRA数据.
  • 采用带有和没有水脂分离 (Dixon) 的消除模糊,分别用于滑动切片LQ (ssLQ) 脱相 (OP) 和迪克逊输入MRA.
  • 与多重重叠薄板收购 (MOTSA) 和2D OP流入MRA的结果进行比较,包括定量SNR和CNR效率评估.

主要成果:

  • 与标准螺旋采集相比,滑动切片螺旋技术减少了10-40%的扫描时间.
  • 螺旋式ssLQ OP实现了比螺旋式MOTSA高50%的扫描速度,具有可比的SNR/CNR效率,在内输入MRA方面比卡尔特斯式MOTSA高了~100%.
关键词:
流入的MRA是指流入的MRA.局部化的二次编码.滑动切片 滑动切片一个螺旋式的螺旋.飞行时间-飞行时间.水-脂肪成像成像技术

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  • 与ssLQ OP MRA相比,螺旋式ssLQ Dixon MRA在脂肪附近提供了更好的血管可见性,速度略有权衡.
  • 使用较薄切片的螺旋式ssLQ MRA比2D卡特西安输入MRA快2-5倍,SNR效率更高.

    • 结论:

    • 拟议的螺旋式ssLQ技术代表了一种快速且可适应的MRA方法.
    • 这种方法提供了优越的SNR和CNR效率,与传统的卡特西安流入MRA技术相比.
    • 该方法有望在临床环境中改善血管成像.