Name: construction and application of cerebral functional region-based cerebral blood flow atlas using magnetic resonance imaging-arterial spin labeling
Uploaded: 2024-05-31T14:35:00.000+00:00
Duration: 5 min 23 s
Description: Cerebral conditions often require precise diagnosis and monitoring, necessitating advanced imaging techniques. Current modalities may not adequately ...

这项研究得到了北京智能熵科技有限公司研发部门的大力支持和建模协助。

本研究经中国北京东直门医院机构审查委员会批准。MRI 扫描仪与基于涡轮梯度自旋回波 （TGSE） 的脉冲 ASL （PASL） 序列用于 3D 动脉自旋标记 （3D-ASL），参数如下:TR 4000 ms，TE 25 ms，推注持续时间 700 ms，反转时间 1990 ms。本研究中使用的软件工具列在 材料表中。
1. 数据收集和准备
注意:参数的差异不受研究方法的影响。DICOM 和 NIFTI 格式都用于存储数字医学成像数据，其中 DICOM 是临床成像设备的常见输出。然而，为了在研究活动中方便计算，NIFTI 格式通常是首选。从 DICOM 转换为 NIFTI 是一种简单而常见的做法17。在本研究中，获取了真实的 DICOM 数据并将其转换为 NIFTI 格式。数据是使用 1.5 特斯拉 MRI 扫描仪采集的。在本研究的交叉图像配准过程中，主要使用流体衰减反转恢复 （FLAIR） 序列，并与 CBF 图像融合。本研究中使用的 CBF Atlas 工具 （Table of Materials） 是商业软件。
<ol><li>将数据复制到指定的工作目录。<ol><li>将所有 NIFTI 数据复制到自定义工作目录。 注意:操作系统和 MATLAB 中的工作目录相同。该研究遵循右前上位 （RAS） 定向标准。</li>
		<li>转到 MATLAB 当前工作目录中包含数据的目录，然后使用 niftiread 函数将 FLAIR 数据加载到工作区中。使用 size 函数检查 FLAIR 序列的维度。调用 Flair_Slice 命令以查看 FLAIR 序列（如图 1 所示）。使用特定命令，如下所示: FLAIR_XLF = niftiread（'FLAIR_XFL.nii'）; 尺寸（FLAIR_XLF） Flair_Slice（FLAIR_XLF）;</li>
		<li>请参阅 图 1 以获取 FLAIR 序列的交互式图形用户界面 （GUI） 的图像。使用底部滚动条可快速浏览不同的序列。</li>
	</ol></li>
	<li>快速检查 CBF 的图像。<ol><li>使用 niftiread 函数将 CBF 数据加载到工作区中。使用 size 函数检查 CBF 序列的维度。调用 CBF_Slice 命令以查看 CBF 序列（如图 2 所示）。使用特定命令，如下所示: CBF_XLF = niftiread（'CBF_XFL.nii'）; 尺寸（CBF_XLF） CBF_Slice（CBF_XLF）;</li>
		<li>请参阅 图 2 以获取 CBF 序列的交互式 GUI 屏幕截图。使用底部滚动条可快速浏览不同的序列。 注:在 图 2 中，CBF 值范围通常为 0-120 mL/100 g/min。 图 2 使用彩图以不同颜色表示不同的 CBF 水平。</li>
	</ol></li>
</ol>2. 从 FLAIR 序列中分割大脑功能区
注:FLAIR 序列既可作为结构成像，又可提供出色的病理诊断能力。因此，将 FLAIR 与 CBF 融合在临床上具有重要的诊断价值。本研究从 FLAIR 序列中分割出主要的大脑功能区域。
<ol><li>在工作区中，调用 FLAIR_Segment 函数并运行预训练的基于 3-D U-Net 的图像分割程序，以自动生成大脑功能区域分割的三平面视图，如图 3 所示。 图 3 中的每种颜色都代表一个不同的功能区域。</li>
	<li>要实时检查不同的大脑功能区域，请使用十字准线交互（图 3）。单击并拖动十字准线的中心，对重建的大脑解剖结构进行任意 3D 检查。 注意: 图 3 中的 GUI 还支持调整三平面视图的灰度强度范围、对比度和亮度。</li>
	<li>在图像的任何区域上按住并拖动鼠标左键，以实时修改亮度和对比度级别。松开鼠标按钮以确认并完成调整。</li>
</ol>3. CBF 跨大脑功能区分布的三平面视图
注意:检查 CBF 在不同大脑功能区域的分布有助于对患者病情进行精确的临床判断。在 图 3 的功能区域框架下，结合 CBF 序列中的确切 CBF 值并以三平面视图呈现它们，可以让医生进行全面的检查。
<ol><li>调用 CBF_triplanar 函数以生成 图 4 中所示的三平面 GUI 视图，显示跨功能区域的 CBF 空间分布。移动十字准线以允许检查感兴趣区域中的 CBF 分布。</li>
	<li>单击 GUI 右上角的 Data Tips 按钮，在任何位置显示 CBF 值。</li>
	<li>在图像的任何区域上按住并拖动鼠标左键，以实时修改亮度和对比度级别。松开鼠标按钮以确认并完成调整。</li>
</ol>4. 跨主要大脑功能区域的 CBF 图谱
注意:对不同功能区的 CBF 概率分布进行标准化会生成大脑功能区 CBF 图谱，表示受试者大脑功能区的 CBF 水平。
<ol><li>调用 CBF_Atlas 函数，将 图 4 中所示的 CBF 空间分布转换为 CBF 图集（如图 5 所示）。 注意:在 图 5 中，x 轴代表不同的大脑功能区域，y 轴代表不同的 CBF 水平;不同的颜色表示不同的概率级别（颜色越红，存在的体素越多）。</li>
	<li>单击图 5 所示的 GUI 右上角的 Zoom In/Out 按钮以缩放部分图像。 注意: 图 5 中的曲线连接了不同地区的平均 CBF。</li>
</ol>5. 健康受试者和 CCI 患者CBF_Atlas差异显著
注意:使用第 1-4 节中描述的相同过程，可以获得 CCI 患者不同大脑功能区域的平均 CBF 值。
<ol><li>利用 CBF_Compare 函数生成健康受试者与 CCI 患者的 CBF 曲线比较图（图 6）。</li>
	<li>观察患者的 CBF 曲线（黑色）和健康曲线（红色）之间的显着差异（图 6）。确定患者 CBF 下降更明显的功能区域。整合步骤 3.3，重新检查与其他区域相比患者表现较差的区域。 注意:步骤 3.3 允许在三维空间中查看患者的 CBF 水平，这意味着医生可以利用 图 4 所示的三平面 GUI 视图来检查患者任何位置的 CBF。在这里，CCI 患者的 CBF 下降程度在不同地区有所不同。医生可以重新访问 图 4 以关注 CBF 显着下降的大脑区域。</li>
	<li>使用 GUI 右上角的图标（图 5）访问缩小、放大、返回全局视图和标记所选像素的坐标等功能。 注意:使用相同的原理，也可以使用 图 6 中的方法比较同一患者的治疗前和治疗后结果，以评估一段时间内的临床疗效。</li>
</ol>

MRI-动脉自旋标记集成以检测和监测脑血流 

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软件工具 CBF Atlas V1.0 是北京智能熵科技有限公司的产品。本软件工具的知识产权归本公司所有。作者没有需要声明的利益冲突。

关键步骤（第 3 节和第 4 节）构成了构建 CBF 图谱的基础，量化了 CBF 在大脑功能区的分布。步骤 4.2 明确描述了每个大脑区域的 CBF 水平，开创了一项新技术。这不仅为医生提供了患者 CBF 的全局视图，还为各个功能区域提供了定量测量。步骤 5.1 表明 CBF 图谱具有区分 CCI 与健康对照的重要临床诊断效用。
一些技术改进可以增强这个有前途的协议，主要是通过利用 MRI-ASL 成像?...

在神经影像学领域，寻求精确、无创的工具来评估脑功能和病理学仍然至关重要。其中，脑血流量 （CBF） 是一个重要的指标，反映了脑组织的代谢需求和健康状况1。传统方法通常需要实证评估，严重依赖临床医生的专业知识来解释图像和辨别病理变化2。然而，磁共振成像 （MRI） 技术的进步，尤其是动脉自旋标记 （ASL）3，为以更高的准确性和客观性量化 CBF 提供了一条有前途的途径 4,5。
本研究提出了一种开创性的方法，该方法将三维 ASL （3D-ASL） 与结构 MRI 相结合，以构建跨大脑功能区域的综合 CBF 图谱6。通过利用这种新方法，临床医生不仅可以获得 CBF 的全局视角，还可以深入研究特定的功能领域，从而对脑灌注模式有细致入微的理解 7,8。分辨率的这种提高是成像设备技术进步的直接结果，而不是使用插值体素。值得注意的是，当今市场上的大多数主流 MRI 设备通常提供优于 1.5 mm9 的成像精度。成像技术的这些进步为更详细和准确的 CBF 评估铺平了道路。这代表了与传统成像的范式转变，传统成像通常缺乏检测与早期病理相关的 CBF 细微变化的分辨率10。
这种方法的起源在于必须解决脑部疾病带来的诊断挑战，包括慢性脑缺血 （CCI） 和其他神经系统疾病11,12。这些情况需要精确和及时的评估，以有效地指导治疗干预13,14。通过比较健康个体和 CCI 患者的 CBF 图谱，本研究揭示了区域 CBF 分布的显着差异，为疾病病理学和可能的治疗途径提供了见解。
这种 MRI-ASL 方法的效用超出了诊断范围，包括治疗评估和疾病进展监测15。纵向 CBF 图谱有望跟踪治疗反应和康复结果，为临床医生提供个性化患者管理的宝贵工具。此外，辨别细微 CBF 变化的能力可以作为即将发生的组织异常的早期生物标志物，从而能够主动干预以减轻神经损伤，以免其变得不可逆16。
虽然这种方法代表了一种高级工具，但值得考虑的几种改进和扩展途径。标准化扫描方案、CBF 标准化技术和构建多受试者健康 CBF 图谱是提高诊断准确性和临床实用性的关键步骤。跨不同脑病理学的协作努力对于验证和改进这种方法以进行广泛的临床采用至关重要。
本研究引入了一种新方法，MRI 衍生的 CBF 图谱为临床医生提供了对脑功能和病理学的深入见解。通过弥合成像组和临床解释之间的差距，这种方法有可能彻底改变无数神经系统疾病的诊断和管理，开创针对每位患者独特需求量身定制的精准医学的未来。

<table><tbody><tr><td>CBF Atlas</td><td>Intelligent Entropy</td><td>CBF Atlas V1.0</td><td>Beijing Intelligent Entropy Science &amp;amp; Technology Co Ltd.&lt;br/&gt; Modeling for Thyroid Disease</td></tr><tr><td>MATLAB</td><td>MathWorks</td><td>2023B</td><td>Computing and visualization</td></tr><tr><td>MRI Device</td><td>Siemens</td><td>Amria 1.5 T</td><td>MRI scanner</td></tr></tbody></table>

construction and application of cerebral functional region-based cerebral blood flow atlas using magnetic resonance imaging-arterial spin labeling

脑部疾病通常需要精确的诊断和监测，因此需要先进的成像技术。目前的方法可能无法充分检测可逆组织损伤的早期迹象，这凸显了对创新诊断工具的需求，这些工具可以以高特异性和敏感性量化脑血流 （CBF） 的变化。本研究将三维动脉自旋标记 （3D-ASL） 与结构 MRI 相结合，以开发涵盖大脑所有主要功能区域的综合 CBF 图谱。这种创新的磁共振成像-动脉自旋标记 （MRI-ASL） 方法提供了一种快速且无创的量化区域特异性 CBF 的方法，提供了不同功能区域的 CBF 水平的详细视图。慢性脑缺血 （CCI） 患者与健康受试者之间的比较显示，在为前者构建的 CBF 图谱中，大脑功能区域的 CBF 显着降低。这种方法不仅可以通过分析关键区域相对于健康分布的 CBF 同时减少来有效识别 CCI，还可以通过纵向 CBF 图谱跟踪治疗反应和康复进展。使用 MRI-ASL 技术开发的 CBF 图谱代表了脑诊断和患者护理领域的新进展。通过将区域 CBF 水平与规范标准进行比较，该方法增强了诊断能力，使临床医生能够为脑部疾病患者提供个性化护理。

这项调查利用使用 1.5 T MRI 扫描仪获取的实际患者数据来验证脑血流 （CBF） 量化和图谱构建方法。预处理步骤包括 FLAIR 结构图像（图 1）、CBF 图像（图 2）和三平面融合图像（图 3 和 图 4）。
使用预先训练的深度学习模型从 FLAIR 扫描中分割出大脑功能区域（图 3?...

作者聚焦:用于诊断神经系统疾病的人类功能脑区无创脑血流测定

本研究整合了磁共振成像-动脉自旋标记图像，以得出脑功能区的脑血流 （CBF） 图谱。比较典型的健康和慢性脑缺血 CBF 图谱揭示了区域 CBF 分布的显着差异，从而能够快速、无创地评估功能性 CBF，以协助诊断和评估治疗。

基于磁共振成像-动脉自旋标记的基于脑功能区的脑血流图谱的构建与应用

Cerebral conditions often require precise diagnosis and monitoring, necessitating advanced imaging techniques. Current modalities may not adequately ...

基于 MRI 的 CBF 图谱提供了一种非侵入性的方式来给出功能性脑区区域的脑血流分布，可能成为脑部疾病领域的重要工具。将成像中的高价值典型指标与生理结构和生化标志物相结合，为医生提供更精确的直径信息。放射成像中的每屏多模态融合、基于 AI 的成像识别和医学专业处理。安全管理 CBF 在患者功能脑区区域的分布的唯一方法是临床诊断和应用脑部疾病的首要方法。使用磁共振成像-动脉自旋标记的基于脑功能区的脑血流图谱提供了技术优势，并准确获取了患者功能性脑区的详细 CBF 信息。

construction-application-cerebral-functional-region-based-cerebral

Universidad de Cartagena UDEC

Research

JoVE Journal

Medicine

Construction and Application of Cerebral Functional Region-Based Cerebral Blood Flow Atlas Using Magnetic Resonance Imaging-Arterial Spin Labeling

472 次观看.  Beijing University of Chinese Medicine. 基于 MRI 的 CBF 图谱提供了一种非侵入性的方式来给出功能性脑区区域的脑血流分布，可能成为脑部疾病领域的重要工具。将成像中的高价值典型指标与生理结构和生化标志物相结合，为医生提供更精确的直径信息。放射成像中的每屏多模态融合、基于 AI 的成像识别和医学专业处理。安全管理 CBF 在患者功能脑区区域的分布的唯一方法是临床诊断和应用脑部疾病的首要方...

视频: 作者聚焦:用于诊断神经系统疾病的人类功能脑区无创脑血流测定

Magnetic Resonance Imaging Quantification of Pulmonary Perfusion using Calibrated Arterial Spin Labeling

This demonstrates a MR imaging method to measure the spatial distribution of pulmonary blood flow in healthy subjects 
during normoxia (inspired O2, fraction (FIO2) = 0.21) hypoxia (FIO2 = 0.125), and hyperoxia 
(FIO2 = 1.00). In addition, the physiological responses of the subject are monitored in the MR scan environment. MR images 
were obtained on a 1.5 T GE MRI scanner during a breath hold from a sagittal slice in the right lung at functional residual capacity. An arterial 
spin labeling sequence (ASL-FAIRER) was used to measure the spatial distribution of pulmonary blood flow 1,2 and a multi-echo fast 
gradient echo (mGRE) sequence 3 was used to quantify the regional proton (i.e. H2O) density, allowing the quantification 
of density-normalized perfusion for each voxel (milliliters blood per minute per gram lung tissue). 
With a pneumatic switching valve and facemask equipped with a 2-way non-rebreathing valve, different oxygen concentrations 
were introduced to the subject in the MR scanner through the inspired gas tubing. A metabolic cart collected expiratory gas via expiratory tubing. Mixed expiratory O2 and CO2 concentrations, oxygen consumption, carbon dioxide production, respiratory exchange ratio, 
respiratory frequency and tidal volume were measured. Heart rate and oxygen saturation were monitored using pulse-oximetry. 
Data obtained from a normal subject showed that, as expected, heart rate was higher in hypoxia (60 bpm) than during normoxia (51) or hyperoxia (50) and the arterial oxygen saturation (SpO2) was reduced during hypoxia to 86%. Mean ventilation was 8.31 L/min BTPS during hypoxia, 7.04 L/min during normoxia, and 6.64 L/min during hyperoxia. Tidal volume was 0.76 L during hypoxia, 0.69 L during normoxia, and 0.67 L during hyperoxia. 
Representative quantified ASL data showed that the mean density normalized perfusion was 8.86 ml/min/g during hypoxia, 8.26 ml/min/g during normoxia and 8.46 ml/min/g during hyperoxia, respectively. In this subject, the relative dispersion4, an index of global heterogeneity, was increased in hypoxia (1.07 during hypoxia, 0.85 during normoxia, and 0.87 during hyperoxia) while the fractal dimension (Ds), another index of heterogeneity reflecting vascular branching structure, was unchanged (1.24 during hypoxia, 1.26 during normoxia, and 1.26 during hyperoxia). 
Overview. This protocol will demonstrate the acquisition of data to measure the distribution of pulmonary perfusion noninvasively under conditions of normoxia, hypoxia, and hyperoxia using a magnetic resonance imaging technique known as arterial spin labeling (ASL). 
Rationale: Measurement of pulmonary blood flow and lung proton density using MR technique offers high spatial resolution images which can be quantified and the ability to perform repeated measurements under several different physiological conditions. In human studies, PET, SPECT, and CT are commonly used as the alternative techniques. However, these techniques involve exposure to ionizing radiation, and thus are not suitable for repeated measurements in human subjects.

A MR imaging method to study the distribution of pulmonary blood flow under a variety of physiological conditions, in this case exposure to three different inspired oxygen concentrations: hypoxia, normoxia, and hyperoxia, is described. This technique utilizes human pulmonary physiology research techniques in an MR scanning environment.

使用校准动脉自旋标记磁共振肺灌注显像定量

This demonstrates a MR imaging method to measure the spatial distribution of pulmonary blood flow in healthy subjects 
during normoxia (inspired O2, ...

科研

医学

High-resolution Functional Magnetic Resonance Imaging Methods for Human Midbrain

Functional MRI (fMRI) is a widely used tool for non-invasively measuring correlates of human brain activity. However, its use has mostly been focused upon measuring activity on the surface of cerebral cortex rather than in subcortical regions such as midbrain and brainstem. Subcortical fMRI must overcome two challenges: spatial resolution and physiological noise. Here we describe an optimized set of techniques developed to perform high-resolution fMRI in human SC, a structure on the dorsal surface of the midbrain; the methods can also be used to image other brainstem and subcortical structures.
High-resolution (1.2 mm voxels) fMRI of the SC requires a non-conventional approach. The desired spatial sampling is obtained using a multi-shot (interleaved) spiral acquisition1. Since, T2* of SC tissue is longer than in cortex, a correspondingly longer echo time (TE ~ 40 msec) is used to maximize functional contrast. To cover the full extent of the SC, 8-10 slices are obtained. For each session a structural anatomy with the same slice prescription as the fMRI is also obtained, which is used to align the functional data to a high-resolution reference volume.
In a separate session, for each subject, we create a high-resolution (0.7 mm sampling) reference volume using a T1-weighted sequence that gives good tissue contrast. In the reference volume, the midbrain region is segmented using the ITK-SNAP software application2. This segmentation is used to create a 3D surface representation of the midbrain that is both smooth and accurate3. The surface vertices and normals are used to create a map of depth from the midbrain surface within the tissue4.
Functional data is transformed into the coordinate system of the segmented reference volume. Depth associations of the voxels enable the averaging of fMRI time series data within specified depth ranges to improve signal quality. Data is rendered on the 3D surface for visualization.
In our lab we use this technique for measuring topographic maps of visual stimulation and covert and overt visual attention within the SC1. As an example, we demonstrate the topographic representation of polar angle to visual stimulation in SC.

This article describes techniques to perform high-resolution functional magnetic resonance imaging with 1.2 mm sampling in human midbrain and subcortical structures using a 3T scanner. Use of these techniques to resolve topographic maps of visual stimulation in the human superior colliculus (SC) is given as an example.

高分辨率人类中脑功能磁共振成像方法

Functional MRI (fMRI) is a widely used tool for non-invasively measuring correlates of human brain activity. However, its use has mostly been focused upon ...

神经科学

Co-analysis of Brain Structure and Function using fMRI and Diffusion-weighted Imaging

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when studying the brain, as the functional role that a brain area fulfills may be largely defined by its connections to other brain areas. In this report, we describe a novel, non-invasive approach for relating brain structure and function using magnetic resonance imaging (MRI). This approach, a combination of structural imaging of long-range fiber connections and functional imaging data, is illustrated in two distinct cognitive domains, visual attention and face perception. Structural imaging is performed with diffusion-weighted imaging (DWI) and fiber tractography, which track the diffusion of water molecules along white-matter fiber tracts in the brain (Figure 1). By visualizing these fiber tracts, we are able to investigate the long-range connective architecture of the brain. The results compare favorably with one of the most widely-used techniques in DWI, diffusion tensor imaging (DTI). DTI is unable to resolve complex configurations of fiber tracts, limiting its utility for constructing detailed, anatomically-informed models of brain function. In contrast, our analyses reproduce known neuroanatomy with precision and accuracy. This advantage is partly due to data acquisition procedures: while many DTI protocols measure diffusion in a small number of directions (e.g., 6 or 12), we employ a diffusion spectrum imaging (DSI)1, 2 protocol which assesses diffusion in 257 directions and at a range of magnetic gradient strengths. Moreover, DSI data allow us to use more sophisticated methods for reconstructing acquired data. In two experiments (visual attention and face perception), tractography reveals that co-active areas of the human brain are anatomically connected, supporting extant hypotheses that they form functional networks. DWI allows us to create a "circuit diagram" and reproduce it on an individual-subject basis, for the purpose of monitoring task-relevant brain activity in networks of interest.

We describe a novel approach for simultaneous analysis of brain function and structure using magnetic resonance imaging (MRI). We assess brain structure with high-resolution diffusion-weighted imaging and white-matter fiber tractography. Unlike standard structural MRI, these techniques allow us to directly relate anatomical connectivity to functional properties of brain networks.

使用功能磁共振成像和弥散加权成像脑结构与功能分析

The study of complex computational systems is facilitated by network maps, such as circuit diagrams. Such mapping is particularly informative when ...

Brain Infarct Segmentation and Registration on MRI or CT for Lesion-symptom Mapping

In lesion-symptom mapping (LSM), brain function is inferred by relating the location of acquired brain lesions to behavioral or cognitive symptoms in a group of patients. With recent advances in brain imaging and image processing, LSM has become a popular tool in cognitive neuroscience. LSM can provide fundamental insights into the functional architecture of the human brain for a variety of cognitive and non-cognitive functions. A crucial step in performing LSM studies is the segmentation of lesions on brains scans of a large group of patients and registration of each scan to a common stereotaxic space (also called standard space or a standardized brain template). Described here is an open-access, standardized method for infarct segmentation and registration for the purpose of LSM, as well as a detailed and hands-on walkthrough based on exemplary cases. A comprehensive tutorial for the manual segmentation of brain infarcts on CT scans and DWI or FLAIR MRI sequences is provided, including criteria for infarct identification and pitfalls for different scan types. The registration software provides multiple registration schemes that can be used for processing of CT and MRI data with heterogeneous acquisition parameters. A tutorial on using this registration software and performing visual quality checks and manual corrections (which are needed in some cases) is provided. This approach provides researchers with a framework for the entire process of brain image processing required to perform an LSM study, from gathering of the data to final quality checks of the results.

Provided here is a practical tutorial for an open-access, standardized image processing pipeline for the purpose of lesion-symptom mapping. A step-by-step walkthrough is provided for each processing step, from manual infarct segmentation on CT/MRI to subsequent registration to standard space, along with practical recommendations and illustrations with exemplary cases.

脑梗死分割和登记在MRI或CT上的病变症状映射

In lesion-symptom mapping (LSM), brain function is inferred by relating the location of acquired brain lesions to behavioral or cognitive symptoms in a ...

行为学

MRI Mapping of Cerebrovascular Reactivity via Gas Inhalation Challenges

The brain is a spatially heterogeneous and temporally dynamic organ, with different regions requiring different amount of blood supply at different time. Therefore, the ability of the blood vessels to dilate or constrict, known as Cerebral-Vascular-Reactivity (CVR), represents an important domain of vascular function. An imaging marker representing this dynamic property will provide new information of cerebral vessels under normal and diseased conditions such as stroke, dementia, atherosclerosis, small vessel diseases, brain tumor, traumatic brain injury, and multiple sclerosis. In order to perform this type of measurement in humans, it is necessary to deliver a vasoactive stimulus such as CO2 and/or O2 gas mixture while quantitative brain magnetic resonance images (MRI) are being collected. In this work, we presented a MR compatible gas-delivery system and the associated protocol that allow the delivery of special gas mixtures (e.g., O2, CO2, N2, and their combinations) while the subject is lying inside the MRI scanner. This system is relatively simple, economical, and easy to use, and the experimental protocol allows accurate mapping of CVR in both healthy volunteers and patients with neurological disorders. This approach has the potential to be used in broad clinical applications and in better understanding of brain vascular pathophysiology. In the video, we demonstrate how to set up the system inside an MRI suite and how to perform a complete experiment on a human participant.

Non-invasive imaging of the brain vasculature&#8217;s ability to dilate or constrict may allow a better understanding of cerebrovascular pathophysiology in various neurological diseases. The present report describes a reproducible and patient-comfortable protocol to perform vascular reactivity imaging in humans using magnetic resonance imaging (MRI).

脑血管反应性通过气体吸入挑战MRI映射

The brain is a spatially heterogeneous and temporally dynamic organ, with different regions requiring different amount of blood supply at different time. ...

Simultaneous PET/MRI Imaging During Mouse Cerebral Hypoxia-ischemia

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics disturbance in affected cells. Diffusion weighted magnetic resonance imaging (MRI) identifies regions that are damaged, potentially irreversibly, by hypoxia-ischemia. Alterations in glucose utilization in the affected tissue may be detectable by positron emission tomography (PET) imaging of 2-deoxy-2-(18F)fluoro-&#7429;-glucose ([18F]FDG) uptake. Due to the rapid and variable nature of injury in this animal model, acquisition of both modes of data must be performed simultaneously in order to meaningfully correlate PET and MRI data. In addition, inter-animal variability in the hypoxic-ischemic injury due to vascular differences limits the ability to analyze multi-modal data and observe changes to a group-wise approach if data is not acquired simultaneously in individual subjects. The method presented here allows one to acquire both diffusion-weighted MRI and [18F]FDG uptake data in the same animal before, during, and after the hypoxic challenge in order to interrogate immediate physiological changes.

The method presented here uses simultaneous positron emission tomography and magnetic resonance imaging. In the cerebral hypoxia-ischemia model, dynamic changes in diffusion and glucose metabolism occur during and after injury. The evolving and irreproducible damage in this model necessitates simultaneous acquisition if meaningful multi-modal imaging data are to be acquired.

同时PET / MRI成像在小鼠脑缺氧缺血

Dynamic changes in tissue water diffusion and glucose metabolism occur during and after hypoxia in cerebral hypoxia-ischemia reflecting a bioenergetics ...

A Magnetic Resonance Imaging Protocol for Stroke Onset Time Estimation in Permanent Cerebral Ischemia

MRI provides a sensitive and specific imaging tool to detect acute ischemic stroke by means of a reduced diffusion coefficient of brain water. In a rat model of ischemic stroke, differences in quantitative T1 and T2 MRI relaxation times (qT1 and qT2) between the ischemic lesion (delineated by low diffusion) and the contralateral non-ischemic hemisphere increase with time from stroke onset. The time dependency of MRI relaxation time differences is heuristically described by a linear function and thus provides a simple estimate of stroke onset time. Additionally, the volumes of abnormal qT1 and qT2 within the ischemic lesion increase linearly with time providing a complementary method for stroke timing. A (semi)automated computer routine based on the quantified diffusion coefficient is presented to delineate acute ischemic stroke tissue in rat ischemia. This routine also determines hemispheric differences in qT1 and qT2 relaxation times and the location and volume of abnormal qT1 and qT2 voxels within the lesion. Uncertainties associated with onset time estimates of qT1 and qT2 MRI data vary from &plusmn; 25 min to &plusmn; 47 min for the first 5 hours of stroke. The most accurate onset time estimates can be obtained by quantifying the volume of overlapping abnormal qT1 and qT2 lesion volumes, termed 'Voverlap' (&plusmn; 25 min) or by quantifying hemispheric differences in qT2 relaxation times only (&plusmn; 28 min). Overall, qT2 derived parameters outperform those from qT1. The current MRI protocol is tested in the hyperacute phase of a permanent focal ischemia model, which may not be applicable to transient focal brain ischemia.

A protocol for stroke onset time estimation in a rat model of stroke exploiting quantitative magnetic resonance imaging (qMRI) parameters is described. The procedure exploits diffusion MRI for delineation of the acute stroke lesion and quantitative T1 and T2 (qT1 and qT2) relaxation times for timing of stroke.

脑缺血中风发作时间估计的磁共振成像协议

MRI provides a sensitive and specific imaging tool to detect acute ischemic stroke by means of a reduced diffusion coefficient of brain water. In a rat ...

Quantification of Cerebral Perfusion using Laser Speckle Imaging and Infarct Volume using MRI in a Pre-clinical Model of Posterior Circulation Stroke

Background: Basilar artery occlusion (BAO) is a subset of posterior circulation stroke that carries a mortality as high as 90%.&#160; The current clinical standard to diagnose ischemic stroke include computerized tomography (CT), CT angiography and perfusion and magnetic resonance imaging (MRI). Large animal pre-clinical models to accurately reflect the clinical disease as well as methods to assess stroke burden and evaluate treatments are lacking.
Methods: We describe a canine model of large vessel occlusion (LVO) stroke in the posterior circulation, and developed a laser speckle imaging (LSI) protocol to monitor perfusion changes in real time.&#160; We then utilized high b-value DWI (b=1800s/mm2) MRI to increase detection sensitivity. We also evaluated the ability of magnetic resonance angiography (MRA) to assess arterial occlusion and correlate with DSA. Finally, we verified infarct size from apparent diffusion coefficient (ADC) mapping with histology.&#160;
Results:&#160; Administration of thromboembolism occluded the basilar artery as tracked by DSA (n=7).&#160; &#160;LSI correlated with DSA, demonstrating a reduction in perfusion after stroke onset that persisted throughout the experiment, allowing us to monitor perfusion in real time.&#160; DWI with an optimized b-value for dogs illustrated the stroke volume and allowed us to derive ADC and magnetic resonance angiography (MRA) images. The MRA performed at the end of the experiment correlated with DSA performed after occlusion. Finally, stroke burden on MRI correlated with histology.
Conclusions: Our studies demonstrate real time perfusion imaging using LSI of a canine thromboembolic LVO model of posterior circulation stroke, which utilizes multimodal imaging important in the diagnosis and treatment of ischemic stroke.

A canine model of LVO stroke was utilized to develop laser speckle imaging to monitor cerebral perfusion in real-time.&#160; Diffusion-weighted MRI was optimized to image infarct volume utilizing a high b-value, enabling ADC and MRA, correlated with DSA at the time of stroke.&#160; Finally, ADC reconstructions correlated with histological findings.

Background: Basilar artery occlusion (BAO) is a subset of posterior circulation stroke that carries a mortality as high as 90%.&#160; The current clinical ...

Human Fetal Blood Flow Quantification with Magnetic Resonance Imaging and Motion Compensation

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the recognized standard-of-care for blood flow quantification based on phase contrast MRI. While such measurement of blood flow has been possible in adults for decades, methods to extend this capability to fetal blood flow have only recently been developed.
Fetal blood flow quantification in major vessels is important for monitoring fetal pathologies such as congenital heart disease (CHD) and fetal growth restriction (FGR). CHD causes alterations in the cardiac structure and vasculature that change the course of blood in the fetus. In FGR, the path of blood flow is altered through the dilation of shunts such that the oxygenated blood supply to the brain is increased. Blood flow quantification enables assessment of the severity of the fetal pathology, which in turn allows for suitable&#160;in utero&#160;patient management and planning for postnatal care.
The primary challenges of applying phase contrast MRI to the human fetus include small blood vessel size, high fetal heart rate, potential MRI data corruption due to maternal respiration, unpredictable fetal movements, and lack of conventional cardiac gating methods to synchronize data acquisition. Here, we describe recent technical developments from our lab that have enabled the quantification of fetal blood flow using phase contrast MRI, including advances in accelerated imaging, motion compensation, and cardiac gating.

Here we present a protocol for measuring fetal blood flow rapidly with MRI and retrospectively performing motion correction and cardiac gating.

通过磁共振成像和运动补偿进行人胎儿血流定量

Magnetic resonance imaging (MRI) is an important tool for the clinical assessment of cardiovascular morphology and heart function. It is also the ...

Concurrent EEG and Functional MRI Recording and Integration Analysis for Dynamic Cortical Activity Imaging

Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are two of the fundamental noninvasive methods for identifying brain activity. Multimodal methods have sought to combine the high temporal resolution of EEG with the spatial precision of fMRI, but the complexity of this approach is currently in need of improvement. The protocol presented here describes the recently developed spatiotemporal fMRI-constrained EEG source imaging method, which seeks to rectify source biases and improve EEG-fMRI source localization through the dynamic recruitment of fMRI sub-regions. The process begins with the collection of multimodal data from concurrent EEG and fMRI scans, the generation of 3D cortical models, and independent EEG and fMRI processing. The processed fMRI activation maps are then split into multiple priors, according to their location and surrounding area. These are taken as priors in a two-level hierarchical Bayesian algorithm for EEG source localization. For each window of interest (defined by the operator), specific segments of the fMRI activation map will be identified as active to optimize a parameter known as model evidence. These will be used as soft constraints on the identified cortical activity, increasing the specificity of the multimodal imaging method by reducing cross-talk and avoiding erroneous activity in other conditionally active fMRI regions. The method generates cortical maps of activity and time-courses, which may be taken as final results, or used as a basis for further analyses (analyses of correlation, causation, etc.) While the method is somewhat limited by its modalities (it will not find EEG-invisible sources), it is broadly compatible with most major processing software, and is suitable for most neuroimaging studies.

An EEG-fMRI multimodal imaging method, known as the spatiotemporal fMRI-constrained EEG source imaging method, is described here. The presented method employs conditionally-active fMRI sub-maps, or priors, to guide EEG source localization in a manner that improves spatial specificity and limits erroneous results.