Name: protocol for the evaluation of mri artifacts caused by metal implants to assess the suitability of implants and the vulnerability of pulse sequences
Uploaded: 2018-05-17T14:00:00.000+00:00
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Description: Watch this Scientific Journal Video about Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences at JoVE.c

作者想感谢萨, 药剂师的药房在海德堡大学医院, 她对 MRI 幻影的贡献。此外, 我们还要感谢 NORAS MRI 产品有限公司 (Höchberg, 德国), 特别是丹尼尔 Gareis 提供了一个原型的16通道多用途线圈。此外, 我们感谢与西门子医疗有限公司 (埃尔兰根, 德国) 的友好合作, 特别是 Nittka 为他们的顺序设置协助。

1. 幻像准备
<ol><li>使用水驱方法确定种植体体积 (例如)。 注: CCT t 样品的容积和 Z t 样品分别测量了0.65 毫升和0.73 毫升。</li>
	<li>使用细螺纹固定在非铁磁、塑料、防水盒中间的植入位置。使用大于预期的 MRI 工件的框。 注: 如果没有对植入物和/或脉冲序列的工件体积进行粗略估计, 则通过将幻像放置在一个盒子中, 在大约10x 大于幻影的范围内填充水来进行测试扫描。本研究的工件体积范围从7.3 毫升 (CCT t 样本) 和0.09 毫升 (Z T 样品) 不等。</li>
	<li>
小心融化合成脂肪 (58.8%), 水 (40%) 和 macrogol-8-stearate (1.2%) 的混合物, 使用水浴在50°c。 注: 对于本研究中的样品, 我们使用了500毫升混合物来嵌入每个样品。<ol>
<li>当混合物变成液体时, 停止加热, 开始缓慢搅拌, 停止加热。确保不存在脂肪和水相的分离。</li>
	</ol>
</li>
	<li>一旦凝血开始, 慢慢开始植入与混合物。为此, 将嵌入的混合物慢慢倒入与植入物的幻框。 注: 浇注必须缓慢, 以避免空气夹杂。</li>
	<li>将幻框与嵌入的植入物放入冰箱, 在4摄氏度过夜, 以干燥。第二天, 通过迁去除任何残余流体部分。</li>
</ol>2. MRI 检查
<ol><li>将幻像 (带有嵌入植入物的框) 置于 MRI 中与体内情况相同的方向。在 MRI 的 isocenter 中定位幽灵的中间位置。</li>
	<li>对于测量, 使用线圈, 允许在成像体积内均匀的信号分布, 没有严重和明显的信号下降 (例如, 头线圈)。</li>
	<li>当在 mri 控制台上规划 mri 扫描时, 请确保幻像盒 (包括方框边缘的一些空气) 在成像量内。</li>
	<li>接下来, 进行 MRI 检查。</li>
</ol>3. 图像分析和后处理
<ol><li>从 MRI 控制台 (例如, 使用 DICOM 格式) 导出图像, 而不会造成任何质量损失 (例如压缩)。在 MRI 后处理软件中导入图像, 允许放置感兴趣的区域 (roi)、评估 ROI 信号强度、基于阈值的分割以及分割卷的量化 (请参见材料表)。</li>
	<li>
要定义堆积工件的阈值, 并检查成像卷内的均匀信号分布, 请将线条垂直放置, 并与切片上可见工件的外部边界相邻, 并将工件大小设置为最大值 (图 1a)。 注: 堆积工件是置换工件, 呈现具有人为高信号强度的区域。它们出现在切片方向和读出方向上。<ol>
<li>将背景 roi (roi背景) 置于四个相交点 (图 1a) 之外的直径10毫米。使用细分编辑器将感兴趣的线条和背景区域放在一起。</li>
		<li>分别测量这些 4 roi背景值和每个 roi背景中所有素的平均信号强度和标准偏差 (SD)。在 "项目" 视图中使用工具材料统计信息。</li>
		<li>确保每个 ROI背景的平均信号强度在其他3个对应的平均信号的 1.5 SD 范围内, 以保证均匀的信号分布。</li>
		<li>通过将 roi 的 3 SD背景添加到这些 4 ROI背景值的所有素的平均信号强度, 计算堆积工件的阈值。对堆积工件进行半自动阈值分割, 方法是选择所有素, 其信号强度大于每个切片中与信号丢失工件相邻的阈值。利用分割编辑器的掩蔽工具对预定义的信号强度范围进行可视化, 并对其进行分割。</li>
	</ol>
</li>
	<li>
要定义信号损耗工件的阈值, 请将4个感兴趣的区域 (ROIs) 放在包含空气的区域 (ROIair; 每10毫米直径) 在幻像框的拐角处, 测量这些 4 ROI 内所有素的平均信号强度和 SD。Air , 如步骤3.2 中所述, 分别使用分段编辑器和 "材料统计"。 注意: 信号损耗工件存在于具有人工低信号强度的素。它们是由 dephasing 和置换工件造成的。<ol>
<li>将 ROI 置于信号丢失工件 (roi核心) 的核心, 由低信号强度的最大连通区域 (图 1a) 定义。手动增加 ROI核心的大小, 直到信号丢失工件中最大可能的大小, 其平均信号强度低于平均 ROI空气+ 各自 SD 的3x。最后, 测量 ROI核心的平均信号强度和 SD。</li>
		<li>通过将 roi核心的 3 SD 添加到 roi核心的平均值, 计算信号损耗工件的信号强度阈值。通过选择所有连接到 ROI核心且信号强度低于阈值的素, 执行基于半自动阈值的信号丢失工件分割。</li>
		<li>利用分割编辑器的掩蔽工具对预定义的信号强度范围进行可视化, 并对其进行分割。如果可能, 请在细分编辑器的分路 "选择" 中使用 "填充" 函数, 以包括尚未选定的分割中的所有素。如果适用, 请手动将其他明确的信号丢失工件添加到分割中。</li>
	</ol>
</li>
	<li>从计算工件体积减去物理种植体体积, 以获得真正的工件体积。重复分析至少3x。至少两周的时间间隔应将多次读取分开, 以排除学习偏差。</li>
</ol>

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蒂姆. Hilgenfeld, Schwindling 和亚历山大 Juerchott 从海德堡大学医学院的博士后奖学金中获得资金。该研究部分由 Dietmar-Hopp-基金会 (项目 23011228) 支持。作者明确指出, 与本条有关的没有利益冲突。

金属植入物患者的数量和 MRI 检查的数量目前正在增加1,2,3。在过去, 关节置换术后, MRI 检查被避免。然而今天, MRI 不仅被要求成像这样的病人, 但也应允许评估并发症直接毗邻关节置换术。因此, 植入物的 mri 安全性和 mri 适用性以及金属工件抑制的鲁棒脉冲序列正变得越来越重要13。为评价 MRI 在工件体积方面...

MRI 已成为不可缺少的诊断工具。因此, 常规诊断中使用的 MRI 系统的数量进一步增加了1。同时, 植入物的患者数量也在增加,2,3。例如, 在 2012年, 超过100万膝关节置换术在美国单独执行了4。在 2010年, 这种植入物的流行率约为 700万, 这相当于80-89 岁5年龄组中10% 以上的女性。因此, MRI 检查的图像质量和诊断意义往往因金属植入物造成的工件受损, 导致诊断准确性降低。因此, 植入物的 MRI 适用性和脉冲序列的工件易损性变得越来越重要。已经发表了许多方法来评估这些特点。然而, 由于使用的评价方法存在很强的差异, 因此很难对各自的结果进行比较。
通过计算其磁化率6, 可以对材料的 MRI 适用性进行评估。然而, 不同的脉冲序列对工件的脆弱性不能与给定植入物的方法相比。反之亦然, 给定脉冲序列的工件卷只能粗略估计不同的植入物. 此外, 分析通常使用人工成形的植入物7,8。由于材料体积和形状对工件大小有影响6, 因此也应考虑这些特性。作为磁易感性的替代品, 工件的尺寸可以被评估。通常, 研究只依赖于工件大小9的定性评估, 或者只关注二维工件大小, 仅覆盖种植工件的一个切片10,11。此外, 通常使用手动分割方法, 这不仅费时费力, 而且容易产生内部和读者之间的差异11。最后, 协议通常不允许在12的同时测试非 fat 饱和和饱和脂肪的序列。然而, 这是可取的, 因为应用脂肪抑制技术深刻影响工件的大小。
在这里, 我们提出一个协议, 它允许可靠的, 半自动的, 基于阈值的, 三维量化的信号丢失和堆积工件的整个植入物, 或所有切片包含可见植入物工件。此外, 它允许测试 T1 和 T2-weighted 图像有或不含脂肪饱和度。该协议可用于评估不同植入物的 MRI 适宜性, 或不同脉冲序列对特定种植体金属工件的易损性。

<table><tbody><tr><td>Aqua B. Braun Ecotainer</td><td>B. Braun Melsungen AG, Melsungen, Germany</td><td></td><td></td></tr><tr><td>Semisynthetic fat: Witepsol W25</td><td>Caelo Caesar &amp;amp; Loretz GmbH, Hilder, Germany</td><td>4051</td><td></td></tr><tr><td>Macrogol-8-stearate</td><td>Caelo Caesar &amp;amp; Loretz GmbH, Hilder, Germany</td><td>3023</td><td></td></tr><tr><td>Plastic box: not specified</td><td></td><td></td><td></td></tr><tr><td>Implants: Nobel Replace</td><td>Nobel Biocare, Z&amp;uuml;rich, Switzerland</td><td></td><td></td></tr><tr><td>Water bath Haake S5P</td><td>Thermo Scientific, Waltham, MA, USA</td><td></td><td></td></tr><tr><td>Measuring cylinder Blaubrand Eterna, Class A, Boro 3.3</td><td>BRAND GmbH + Co Kg, Wertheim, Germany</td><td>32708</td><td></td></tr><tr><td>Coil: Variety</td><td>Noras MRI products GmbH, H&amp;ouml;chberg, Germany</td><td></td><td></td></tr><tr><td>MRI: Magnetom Trio</td><td>Siemens Healthcare GmbH, Erlangen, Germany</td><td></td><td></td></tr><tr><td>Postprocesing software: Amira 6.4</td><td>Thermo Scientific, Waltham, MA, USA</td><td></td><td></td></tr></tbody></table>

protocol for the evaluation of mri artifacts caused by metal implants to assess the suitability of implants and the vulnerability of pulse sequences

随着磁共振成像 (mri) 扫描仪和医用植入物的数量不断增加, 放射科医生在 MRI 中越来越多地遇到与金属植入相关的工件, 从而降低了图像质量。因此, 植入物体积的 MRI 适配性以及脉冲序列的发展对减少图像工件的作用越来越重要。在这里, 我们提出了一个全面的协议, 允许对植入物体积的 MRI 的标准化评估。此外, 该协议还可用于分析不同脉冲序列对工件的易损性。所提出的协议可以应用于 T1 和 T2-weighted 图像, 有或不含脂肪抑制和所有被动植入物。此外, 该程序还实现了信号丢失和堆积工件的分离和三维识别。由于以往的调查在评价方法上差异很大, 结果的可比性有限。因此, 必须对 MRI 工件体积进行标准化测量, 以提供更好的可比性。这可能会改善植入物 MRI 的适用性和更好的脉搏序列, 以最终改善病人的护理。

通过上述协议, 我们评估了2种不同牙种植体的工件体积 (T; 参见材料表) 支持不同的冠 [瓷熔化对金属非贵金属合金 (CCT t) 和整体氧化锆 (Z T);图 1b和1c]。CCT T 样品代表高度顺磁性材料组分预测大文物 (钴 61%, 铬21% 和钨 11%;CCT)。Z T 样品的冠材料代表低顺磁性材料 (氧化锆 92%;Z). 此外, 评估了四种不同的、非脂肪饱和的 T2-weighted ?...

Watch this Scientific Journal Video about Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences at JoVE.c

Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences

我们描述了一种标准化的方法来评估植入物引起的磁共振成像工件, 以估计植入物对磁共振成像的适用性和/或不同脉冲序列对金属工件的易损性。同时。

评估植入物所引起的 MRI 伪影和脉冲序列易损性评估的协议

As the number of magnetic resonance imaging (MRI) scanners and patients with medical implants is constantly growing, radiologists increasingly encounter ...

protocol-for-evaluation-mri-artifacts-caused-metal-implants-to-assess

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

9.8K 次观看.  Heidelberg University Hospital. 我们描述了一种标准化的方法来评估植入物引起的磁共振成像工件, 以估计植入物对磁共振成像的适用性和/或不同脉冲序列对金属工件的易损性。同时。

视频: Protocol for the Evaluation of MRI Artifacts Caused by Metal Implants to Assess the Suitability of Implants and the Vulnerability of Pulse Sequences

Tracking the Mammary Architectural Features and Detecting Breast Cancer with Magnetic Resonance Diffusion Tensor Imaging

Breast cancer is the most common cause of cancer among women worldwide. Early detection of breast cancer has a critical role in improving the quality of life and survival of breast cancer patients. In this paper a new approach for the detection of breast cancer is described, based on tracking the mammary architectural elements using diffusion tensor imaging (DTI). 
The paper focuses on the scanning protocols and image processing algorithms and software that were designed to fit the diffusion properties of the mammary fibroglandular tissue and its changes during malignant transformation. The final output yields pixel by pixel vector maps that track the architecture of the entire mammary ductal glandular trees and parametric maps of the diffusion tensor coefficients and anisotropy indices. 
The efficiency of the method to detect breast cancer was tested by scanning women volunteers including 68 patients with breast cancer confirmed by histopathology findings. Regions with cancer cells exhibited a marked reduction in the diffusion coefficients and in the maximal anisotropy index as compared to the normal breast tissue, providing an intrinsic contrast for delineating the boundaries of malignant growth. Overall, the sensitivity of the DTI parameters to detect breast cancer was found to be high, particularly in dense breasts, and comparable to the current standard breast MRI method that requires injection of a contrast agent. Thus, this method offers a completely non-invasive, safe and sensitive tool for breast cancer detection.

We describe how to obtain parametric and vector maps of the diffusion tensor of the breast using magnetic resonance imaging. The protocol and final output following imaging processing are tailored for tracking breast architectural features and detecting breast malignancy.

跟踪乳腺建筑特色与检测乳腺癌的磁共振扩散张量成像

Breast cancer is the most common cause of cancer among women worldwide. Early detection of breast cancer has a critical role in improving the quality of ...

科研

医学

Quantitative Magnetic Resonance Imaging of Skeletal Muscle Disease

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of living systems. Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using qMRI methods. The MRI acquisition protocol begins with localizer images (used to locate the position of the body and tissue of interest within the MRI system), quality control measurements of relevant magnetic field distributions, and structural imaging for general anatomical characterization. The qMRI portion of the protocol includes measurements of the longitudinal and transverse relaxation time constants (T1 and T2, respectively). Also acquired are diffusion-tensor MRI data, in which water diffusivity is measured and used to infer pathological processes such as edema. Quantitative magnetization transfer imaging is used to characterize the relative tissue content of macromolecular and free water protons. Lastly, fat-water MRI methods are used to characterize fibro-adipose tissue replacement of muscle. In addition to describing the data acquisition and analysis procedures, this paper also discusses the potential problems associated with these methods, the analysis and interpretation of the data, MRI safety, and strategies for artifact reduction and protocol optimization.

Neuromuscular diseases often exhibit a temporally varying, spatially heterogeneous, and multi-faceted pathology. The goal of this protocol is to characterize this pathology using non-invasive magnetic resonance imaging methods.

骨骼肌疾病的定量磁共振成像

Quantitative magnetic resonance imaging (qMRI) describes the development and use of MRI to quantify physical, chemical, and/or biological properties of ...

A Multicenter MRI Protocol for the Evaluation and Quantification of Deep Vein Thrombosis

We evaluated a magnetic resonance venography (MRV) approach with gadofosveset to quantify total thrombus volume changes as the principal criterion for treatment efficacy&#160;in a multicenter randomized study comparing edoxaban monotherapy with a heparin/warfarin regimen for acute, symptomatic lower extremities deep vein thrombosis (DVT) treatment. We also used a direct thrombus imaging approach (DTHI, without the use of a contrast agent) to quantify fresh thrombus. We then sought to evaluate the reproducibility of the analysis methodology and applicability of using 3D magnetic resonance venography and direct thrombus imaging for the quantification of DVT in a multicenter trial setting. From 10 randomly selected subjects participating in the edoxaban Thrombus Reduction Imaging Study (eTRIS), total thrombus volume in the entire lower extremity deep venous system was quantified bilaterally. Subjects were imaged using 3D-T1W gradient echo sequences before (direct thrombus imaging, DTHI) and 5 min after injection of 0.03 mmol/kg of gadofosveset trisodium (magnetic resonance venography, MRV). The margins of the DVT on corresponding axial, curved multi-planar reformatted images were manually delineated by two observers to obtain volumetric measurements of the venous thrombi. MRV was used to compute total DVT volume, whereas DTHI was used to compute volume of fresh thrombus. Intra-class correlation (ICC) and Bland Altman analysis were performed to compare inter and intra-observer variability of the analysis. The ICC for inter and intra-observer variability was excellent (0.99 and 0.98, p &#60;0.001, respectively) with no bias on Bland-Altman analysis for MRV images. For DTHI images, the results were slightly lower (ICC = 0.88 and 0.95 respectively, p &#60;0.001), with bias for inter-observer results on Bland-Altman plots. This study showed feasibility of thrombus volume estimation in DVT using MRV with gadofosveset trisodium, with good intra- and inter-observer reproducibility in a multicenter setting.

The goal of this study is to use magnetic resonance venography with long-circulating gadolinium-based contrast agent and direct thrombus imaging for quantitative evaluation of DVT volume in a multicenter, clinical trial setting. Inter- and intra-observer variability assessments were conducted, and reproducibility of the protocol was determined.

深静脉血栓形成的评价和定量的多中心MRI协议

We evaluated a magnetic resonance venography (MRV) approach with gadofosveset to quantify total thrombus volume changes as the principal criterion for ...

Optogenetic Functional MRI

The investigation of the functional connectivity of precise neural circuits across the entire intact brain can be achieved through optogenetic functional magnetic resonance imaging (ofMRI), which is a novel technique that combines the relatively high spatial resolution of high-field fMRI with the precision of optogenetic stimulation. Fiber optics that enable delivery of specific wavelengths of light deep into the brain in vivo are implanted into regions of interest in order to specifically stimulate targeted cell types that have been genetically induced to express light-sensitive trans-membrane conductance channels, called opsins. fMRI is used to provide a non-invasive method of determining the brain's global dynamic response to optogenetic stimulation of specific neural circuits through measurement of the blood-oxygen-level-dependent (BOLD) signal, which provides an indirect measurement of neuronal activity. This protocol describes the construction of fiber optic implants, the implantation surgeries, the imaging with photostimulation and the data analysis required to successfully perform ofMRI. In summary, the precise stimulation and whole-brain monitoring ability of ofMRI are crucial factors in making ofMRI a powerful tool for the study of the connectomics of the brain in both healthy and diseased states.

This protocol describes the steps and data analysis required to successfully perform optogenetic functional magnetic resonance imaging (ofMRI). ofMRI is a novel technique that combines high-field fMRI readout with optogenetic stimulation, allowing for cell type-specific mapping of functional neural circuits and their dynamics across the whole living brain.

光遗传学功能磁共振成像

The investigation of the functional connectivity of precise neural circuits across the entire intact brain can be achieved through optogenetic functional ...

神经科学

Equipment Setup and Artifact Removal for Simultaneous Electroencephalogram and Functional Magnetic Resonance Imaging for Clinical Review in Epilepsy

Simultaneous electroencephalogram and functional magnetic resonance imaging (EEG-fMRI) is a unique combined technique that provides synergy in the understanding and localization of seizure onset in epilepsy. However, reported experimental protocols for EEG-fMRI recordings fail to address details about conducting such procedures on epilepsy patients. In addition, these protocols are limited solely to research settings. To fill the gap between patient monitoring in an epilepsy monitoring unit (EMU) and conducting research with an epilepsy patient, we introduce a unique EEG-fMRI recording protocol of epilepsy during the interictal period. The use of an MR conditional electrode set, which can also be used in the EMU for a simultaneous scalp EEG and video recording, allows an easy transition of EEG recordings from the EMU to the scanning room for concurrent EEG-fMRI recordings. Details on the recording procedures using this specific MR conditional electrode set are provided. In addition, the study explains step-by-step EEG processing procedures to remove the imaging artifacts, which can then be used for clinical review. This experimental protocol promotes an amendment to the conventional EEG-fMRI recording for enhanced applicability in both clinical (i.e., EMU) and research settings. Furthermore, this protocol provides the potential to expand this modality to postictal EEG-fMRI recordings in the clinical setting.

This article details simultaneous electroencephalogram and functional magnetic resonance imaging (EEG-fMRI) recording procedures that can be used in both clinical and research settings. EEG processing procedures to remove imaging artifacts for clinical review are also included. This study focuses on the example of epilepsy during the interictal period.

同步脑电图和功能性磁共振成像的设备设置和伪影去除，用于癫痫临床审查

Simultaneous electroencephalogram and functional magnetic resonance imaging (EEG-fMRI) is a unique combined technique that provides synergy in the ...

生物工程

Cardiac Magnetic Resonance for the Evaluation of Suspected Cardiac Thrombus: Conventional and Emerging Techniques

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The appearance of a mass on certain magnetic resonance (MR) sequences can help differentiate a thrombus from competing diagnoses such as a tumor. T1 and T2 signal characteristics of a thrombus are related to the evolution of hemoglobin properties. A thrombus typically does not enhance following contrast administration, which also helps differentiation from a tumor. We also highlight the emerging role of T1 mapping in the evaluation of a thrombus, which can add another level of support in diagnosis. Prior to any CMR exam, patient screening and interviews are critical to ensure safety and to optimize patient comfort. Effective communication during the exam between the technologist and the patient promotes proper breath holding technique and higher quality images. Volumetric post processing and structured reporting are helpful to ensure that the radiologist answers the ordering services&#39; question and communicates these results effectively. Optimal pre-MR safety evaluation, CMR exam execution, and post exam processing and reporting allow for delivery of high quality radiological service in the evaluation of a suspected cardiac thrombus.

The goal of this article is to describe how cardiac magnetic resonance can be used for the evaluation and diagnosis of a suspected cardiac thrombus. The method presented will describe data acquisition as well as the pre-procedure and post-procedure protocol.

心脏磁共振评估疑似心脏血栓:常规和新兴技术

We present the conventional cardiac magnetic resonance (CMR) protocol for evaluating a suspected thrombus and highlight emerging techniques.&#160;The ...

Reliable Acquisition of Electroencephalography Data during Simultaneous Electroencephalography and Functional MRI

Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), EEG-fMRI, combines the complementary properties of scalp EEG (good temporal resolution) and fMRI (good spatial resolution) to measure neuronal activity during an electrographic event, through hemodynamic responses known as blood-oxygen-level-dependent (BOLD) changes. It is a non-invasive research tool that is utilized in neuroscience research and is highly beneficial to the clinical community, especially for the management of neurological diseases, provided that proper equipment and protocols are administered during data acquisition. Although recording EEG-fMRI is apparently straightforward, the correct preparation, especially in placing and securing the electrodes, is not only important for safety but is also critical in ensuring the reliability and analyzability of the EEG data obtained. This is also the most experience-demanding part of the preparation. To address these issues, a straightforward protocol that ensures data quality was developed. This article provides a step-by-step guide for acquiring reliable EEG data during EEG-fMRI using this protocol that utilizes readily available medical products. The presented protocol can be adapted to different applications of EEG-fMRI in research and clinical settings, and may be beneficial to both inexperienced and expert operators.

This article provides a straightforward protocol for acquiring good quality electroencephalography (EEG) data during simultaneous EEG and functional magnetic resonance imaging by utilizing readily available medical products.

同时脑电图和功能 MRI 期间的可靠脑成像数据获取

Simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), EEG-fMRI, combines the complementary properties of scalp EEG ...

Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla

The overall goal of this article is to demonstrate a state-of-the-art ultrahigh field (UHF) magnetic resonance (MR) protocol of the brain at 7.0 Tesla in multiple sclerosis (MS) patients. MS is a chronic inflammatory, demyelinating, neurodegenerative disease that is characterized by white and gray matter lesions. Detection of spatially and temporally disseminated T2-hyperintense lesions by the use of MRI at 1.5 T and 3 T represents a crucial diagnostic tool in clinical practice to establish accurate diagnosis of MS based on the current version of the 2017 McDonald criteria. However, the differentiation of MS lesions from brain white matter lesions of other origins can sometimes be challenging due to their resembling morphology at lower magnetic field strengths (typically 3 T). Ultrahigh field MR (UHF-MR) benefits from increased signal-to-noise ratio and enhanced spatial resolution, both key to superior imaging for more accurate and definitive diagnoses of subtle lesions. Hence, MRI at 7.0 T has shown encouraging results to overcome the challenges of MS differential diagnosis by providing MS-specific neuroimaging markers (e.g., central vein sign, hypointense rim structures and differentiation of MS grey matter lesions). These markers and others can be identified by other MR contrasts other than T1 and T2 (T2*, phase, diffusion) and substantially improve the differentiation of MS lesions from those occurring in other neuroinflammatory conditions such as neuromyelitis optica and Susac syndrome. In this article, we describe our current technical approach to study cerebral white and grey matter lesions in MS patients at 7.0 T using different MR acquisition methods. The up-to-date protocol includes the preparation of the MR setup including the radio-frequency coils customized for UHF-MR, standardized screening, safety and interview procedures with MS patients, patient positioning in the MR scanner and acquisition of dedicated brain scans tailored for examining MS.

Here, we present a protocol to acquire magnetic resonance (MR) images of multiple sclerosis (MS) patient brains at 7.0 Tesla. The protocol includes preparation of the setup including the radio-frequency coils, standardized interview procedures with MS patients, subject positioning in the MR scanner and MR data acquisition.

7.0特斯拉多发性硬化症的磁共振成像

The overall goal of this article is to demonstrate a state-of-the-art ultrahigh field (UHF) magnetic resonance (MR) protocol of the brain at 7.0 Tesla in ...

Clinical Indications for Rapid Sequence MRI in Pediatric Neurosurgical Patients and the Limitations and Barriers to Implementation

Rapid and fast magnetic resonance imaging (MRI) protocols have become increasingly popular for pediatric neurosurgical patients as they are a great way to reduce ionizing radiation and sedation. While their popularity has increased, there are hurdles to overcome when transitioning to using them clinically, such as cost, staffing training, and motion artifact. Through this paper, we developed a protocol for clinical applications where rapid MRI can be a substitute or adjuvant in diagnostic workup. Further, we outline the relevant literature for the use of RS-MRI for the spine, TBI, and hydrocephalus pathologies while expanding upon the limitations and logistical barriers when transitioning to their use, a few of which are discussed above. Through this, we conclude that RS-MRI can be used diagnostically for spinal pathologies such as syrinx and hydrocephalus. Further, its lack of sensitivity for TBI findings makes rapid sequence magnetic resonance imaging (RS-MRI) a strong adjuvant with other advanced imaging or computed tomography (CT) for traumatic brain injury (TBI) pathologies.

Here, we present a protocol to increase the use of rapid sequence magnetic resonance imaging (RS-MRI) for pediatric patients for spine, traumatic brain injury (TBI), and hydrocephalus while documenting limitations and barriers to universal implementation.

Rapid and fast magnetic resonance imaging (MRI) protocols have become increasingly popular for pediatric neurosurgical patients as they are a great way to ...

Magnetic Resonance Imaging

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 scanners were crude, but advances in digital computing and electronics led to their advancement over any other technique for precise imaging, especially in discovering tumors. Compared to other diagnostic imaging techniques like computed tomography and X-ray, MRI does not expose patients to radiation.
The drawbacks of MRI scans include their much higher cost and patient discomfort with the procedure. The MRI scanner subjects the patient to such powerful electromagnets that the scan room must be shielded. The patient must be enclosed in a metal tube-like device for the duration of the scan, sometimes as long as thirty minutes, which can be uncomfortable and impractical for ill patients. The machine is also so noisy that, even with earplugs, patients can become anxious or fearful. These problems have been overcome somewhat with the development of &#34;open&#34;&#160;MRI scanning, which does not require the patient to be entirely enclosed in a metal tube. Patients with iron-containing metallic implants (internal sutures, some prosthetic devices, pacemakers and so on) cannot undergo MRI scanning because it can dislodge these implants.
Different images are formed depending on the time taken between the sequence of magnetic pulses and the receipt and interpretation of the signal. A T1-weighted image has fatty tissues appearing brighter due to their enhanced signal while suppressing water signals, making it appear darker. In contrast, the T2-weighted image shows an enhanced water signal. Further, using MRI contrast media or dyes, like gadolinium, helps improve the quality of the images. Usually injected into the patient&#39;s vein, the gadolinium contrast dyes contain strongly paramagnetic gadolinium (Gd), which has positive magnetic susceptibility. When placed in a magnetic field, it is not directly seen in the MRI result but helps shorten the T1 values in tissues, where it accumulates, which allows the tissues to appear brighter in T1-weighted images.
Functional MRIs (fMRI), which detect the concentration of blood flow in certain body parts, are increasingly being used to study the activity in parts of the brain during various body activities. This has helped scientists learn more about the locations of different brain functions and more about brain abnormalities and diseases. More recently, 4D flow MRI provides 3D blood flow images and hemodynamics, with the fourth dimension being time, allowing cardiovascular disease assessment through the 3D coverage of the anatomy and velocity.
This content is derived from <a href="https://openstax.org/books/anatomy-and-physiology/pages/1-7-medical-imaging">Openstax, Anatomy and Physiology, Section 1.7: Medical Imaging</a>

磁共振成像

Magnetic resonance imaging (MRI) is a noninvasive medical imaging technique based on a phenomenon of nuclear physics discovered in the 1930s, in which ...