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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<li>Schenck, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+role+of+magnetic+susceptibility+in+magnetic+resonance+imaging%3A+MRI+magnetic+compatibility+of+the+first+and+second+kinds%5BTitle%5D)+AND+%22Medical+Physics%22%5BJournal%5D)">The role of magnetic susceptibility in magnetic resonance imaging: MRI magnetic compatibility of the first and second kinds.</a> Medical Physics. 23 (6), 815-850 (1996).</li>
<li>Filli, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Material-dependent+implant+artifact+reduction+using+SEMAC-VAT+and+MAVRIC%3A+a+prospective+MRI+phantom+study%5BTitle%5D)+AND+%22Investigative+Radiology%22%5BJournal%5D)">Material-dependent implant artifact reduction using SEMAC-VAT and MAVRIC: a prospective MRI phantom study.</a> Investigative Radiology. 52 (6), 381(2017).</li>
<li>Klinke, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Artifacts+in+magnetic+resonance+imaging+and+computed+tomography+caused+by+dental+materials%5BTitle%5D)+AND+%22PloS+ONE%22%5BJournal%5D)">Artifacts in magnetic resonance imaging and computed tomography caused by dental materials.</a> PloS ONE. 7 (2), (2012).</li>
<li>Lee, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Usefulness+of+IDEAL+T2-weighted+FSE+and+SPGR+imaging+in+reducing+metallic+artifacts+in+the+postoperative+ankles+with+metallic+hardware%5BTitle%5D)+AND+%22Skeletal+Radiology%22%5BJournal%5D)">Usefulness of IDEAL T2-weighted FSE and SPGR imaging in reducing metallic artifacts in the postoperative ankles with metallic hardware.</a> Skeletal Radiology. 42 (2), 239-247 (2013).</li>
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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 在工件体积方面的适用性, 提出了一种综合、高效的实时协议。它允许对信号损耗和堆积工件进行可靠的三维评估, 作为抑制脂肪和非脂肪抑制 T1 和 T2-weighted 脉冲序列的切片畸变的指示器。
对于某些协议步骤, 必须特别注意以达到最佳的可能结果。熔化后的嵌入物质和植入之前, 它是非常重要的搅拌嵌入物质足够长, 而它开始降温, 其总状态变化 (流体到固体), 因为它的脂肪和水相容易分离, 即使在乳化剂的存在。此外, 用嵌入物质慢慢填充幻框是很重要的, 以避免气泡。这是至关重要的, 因为空气和信号损耗工件都导致零信号, 这将导致高估的工件。
一个高和均匀的信号是必要的, 以便对工件体积的准确评估。如果表面线圈达到最高的信噪比 (信噪比), 那么预先测试轮廓和线圈定位的灵敏度是否允许幻像中的齐次信号 (如上所述) 是至关重要的, 这样基于阈值的分割可以在没有任何分割错误的情况下运行。
与其他分析大型植入物 (例如、髋关节或膝关节置换或 spondylodesis) 的研究相比, 本协议使用的是小型植入物, 在某些情况下导致工件体积远低于1毫升。即使在如此具有挑战性的条件下, 我们也能发现不同样本和不同脉冲序列之间的工件体积存在显著的差异。因此, 可以假定该协议具有较高的测量精度, 从而能够准确地评估复杂植入物的 MRI 伪影体积和材料组成和形状。此外, 该协议可用于比较不同脉冲序列的脆弱性与金属诱发的工件所造成的特定种植体。
对金属工件的评价提出了多种不同复杂度的方法。为了比较不同的脉冲序列, 弗里茨et使用定性排名来评估每个序列11的漏洞。其他的, 例如 Zho et, 通过测量最大距离和通过平面工件来确定在平面工件 (信号丢失和堆积) 卷中, 通过计算受工件影响的切片数10。然而, 这两种方法都不考虑完整的工件体积, 这可能导致工件体积不足或高估。这也适用于一些使用手动分割11的研究。因为这是一个非常耗时的方法, 通常只有一个或两个中心切片在视觉基础上进行评估, 忽略剩余工件比例。
对于体外研究, 作者经常使用琼脂糖或明胶作为嵌入物质14,15。这两种材料都可以很容易地处理, 并保证足够的信号 T2 和 T1-weighted 图像。然而, 它们不允许对任何加权中的脂肪抑制序列进行评估。这是一个主要的缺点, 因为脂肪抑制对工件体积有深远的影响, 经常用于识别与植入物相关的并发症 (例如, 在感染病例中与种植体相邻的水肿和液体收集,微粒疾病, 或无菌淋巴细胞为主的血管炎-关联病变)13,16,17。
必须确认此协议的某些限制。首先, 它不允许对工件体积进行体内量化, 因为完整工件体积的差异需要一个均匀的背景信号。对于体内评估, 可以使用其他方法 (如测量磁性敏感度)。第二, 该协议允许检测堆积工件 (作为切片畸变的指示器), 仅与信号丢失工件直接相邻。但是, 除了信号丢失工件之外, 还可以预期额外的切片失真。这就是为什么可能低估了扭曲量的原因。
最后, 本协议有助于规范未来的研究, 评估植入物的 MRI 伪影体积和脉冲序列对金属工件的脆弱性。这可能有助于优化植入物和序列技术的 MRI 适用性, 最终改善病人护理。

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 序列, 以比较它们对金属工件的易损性。具体来说, 基于抽样完美的多角度倾斜梯度技术, 利用不同的翻转角演化 (MSVAT 空间), 金属工件的切片编码, 采用优化的对比度。校正 (SEMAC), 和他们的传统对应空间和涡轮旋转回声 (谢) 被评估 (参见表 1为详细的序列参量)。mri 扫描是在 3T mri 系统上进行的 (见材料表), 使用16通道多用途表面线圈。脉冲序列参数的变化对工件尺寸有很大的影响。因此, 脉冲序列参数选择尽可能接近于体内牙科 MRI 扫描中使用的, 以增加结果的可转移性。这项分析是由两名独立评分人3x 完成的。对于多项比较, 使用了方差分析和自组后Tukey 测试。
数据分析揭示了样本和应用序列之间的差异。在所有序列中, 与 Z t 样本 (P < 0.001 相比, CCT t 样本的组合工件体积 (信号损耗和堆积的总和) 较大;图 2和图 3)。在同一序列中, CCT t 样本的工件体积为 19.3x (SEMAC) 到 39.6x (MSVAT 空间), 大于 Z T 对应件的工件体积。
脉冲序列的选择对工件体积也有显著影响 (图 2和图 3)。对于 CCT T 样例, 为谢和 SEMAC 观察到最小工件体积, 以及空间中最大的工件 (P < 0.001)。此外, 与空间相比, MSVAT 空间显著降低了工件体积 (P < 0.001; 3.8 vs 7.3 mL)。与此相反, MSVAT 空间、谢和 SEMAC 的 Z T 样本之间没有显著差异。Z T 的工件体积最大, MSVAT 空间 (P < 0.05; 0.26 vs 0.1 mL) 显著减少。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57394/57394fig1v2.jpg"> 图 1: ROI 定位和植入样例.(a) 此面板显示了感兴趣区域的典型位置 (ROIs), 用于测量堆积工件和信号分布的阈值 (roiB = roi背景) 和信号丢失工件 (roi = roi 空气;roiC = roi核心)。蓝色轮廓类似于该切片中的信号丢失工件的半自动分割结果。小红区域对应于堆积物的结果。(b和c) 这些面板显示了用于支持不同单冠的旧牙种植体的图像。钴铬钨钛 (CCT T);氧化锆钛 (Z T)。<a href="/files/ftp_upload/57394/57394fig1v2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57394/57394fig2v2.jpg"> 图 2: 工件体积测量.(a和b)这些条形图显示了在减去物理种植体体积后, 所有4个评估序列的三维工件体积的标准偏差的平均值。如果适用, 则为信号丢失和堆积工件提供单独的标准偏差误差条。* P ≤ 0.05;** P≤ 0.001<a href="/files/ftp_upload/57394/57394fig2v2large.jpg" target="_blank">请单击此处查看此图的更大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57394/57394fig3.jpg"> 图 3: 工件的外观.这些面板渲染整个植入物的工件体积 (上部行)。蓝色区域代表信号丢失工件, 红色区域代表堆积工件。面板显示所有计算的 T2-weighted 序列的彩色源图像 (下一行)。面板 (a) 是钴铬钨钛 (CCT t) 样品, 面板 (b) 是氧化锆-钛 (Z T) 样品。<a href="/files/ftp_upload/57394/57394fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<table fo:font-size="7" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody>
<tr>
<td>序列</td>
			<td>TR/特 女士]</td>
			<td>体素尺寸 [mm3]</td>
			<td>FOV [mm2]</td>
			<td>矩阵</td>
			<td>读数 带宽 [Hz/Px]</td>
			<td>片</td>
			<td>
片 编码 步骤或 采样 [%]
</td>
			<td>增值税</td>
			<td>时间 [最少: 秒]</td>
		</tr>
<tr>
<td>空间</td>
			<td>2500/131</td>
			<td>0.55 x 0.55 x 0.55</td>
			<td>140 x 124</td>
			<td>256 x 256</td>
			<td>501</td>
			<td>72</td>
			<td>55。6</td>
			<td>不</td>
			<td>14:02</td>
		</tr>
<tr>
<td>MSVAT 空间</td>
			<td>2500/199</td>
			<td>0.55 x 0.55 x 0.55</td>
			<td>140 x 84</td>
			<td>256 x 256</td>
			<td>528</td>
			<td>72</td>
			<td>55。6</td>
			<td>是的</td>
			<td>6:04</td>
		</tr>
<tr>
<td>谢</td>
			<td>5100/44</td>
			<td>0.59 x 0.59 x 1。5</td>
			<td>150 x 150</td>
			<td>256 x 256</td>
			<td>592</td>
			<td>25</td>
			<td>不</td>
			<td>不</td>
			<td>3:36</td>
		</tr>
<tr>
<td>SEMAC</td>
			<td>5100/45</td>
			<td>0.59 x 0.59 x 1。5</td>
			<td>150 x 150</td>
			<td>256 x 256</td>
			<td>592</td>
			<td>25</td>
			<td>4</td>
			<td>是的</td>
			<td>6:19</td>
		</tr>
</tbody></table>表 1: 所有已用序列的参数。

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

Nanyang Technological University

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

Microwave-driven Synthesis of Iron Oxide Nanoparticles for Fast Detection of Atherosclerosis

A fast and reproducible microwave-driven protocol has been developed for the synthesis of neridronate-functionalized nanoparticles. Starting from the synthesis of hydrophobic nanoparticles, our method is based on an adaptation from thermal decomposition method to microwave driven synthesis. The new methodology produces a decrease in the reaction times in comparison with traditional procedures. Moreover, the use of the microwave technology increases the reproducibility of the reactions, something important from the point of view of clinical applications. The novelty of this iron oxide nanoparticle is the attachment of Neridronate. The use of this molecule leads a bisphosphonate moiety towards the outside of the nanoparticle that provides Ca2+ binding properties in vitro and selective accumulation in vivo in the atheroma plaque. The protocol allows the synthesis and plaque detection in about 3 hr since the initial synthesis from organic precursors. Their accumulation in the atherosclerotic area in less than 1 hr provides a contrast agent particularly suitable for clinical applications.

Microwave technology enables extremely fast synthesis of iron oxide nanoparticles for atherosclerosis plaque characterization. The use of an aminobisphosphonate in the external side of the nanoparticle provides a fast accumulation in the atherosclerotic area.

动脉粥样硬化的快速检测的氧化铁纳米颗粒微波驱动综合

A fast and reproducible microwave-driven protocol has been developed for the synthesis of neridronate-functionalized nanoparticles. Starting from the ...

科研

生物工程

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 ...

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 ...

Quantitative MRI of Endothelial Permeability and (Dys)function in Atherosclerosis

Cardiovascular diseases are the leading causes of death worldwide. A permeable/leaky and dysfunctional endothelium is considered the earliest marker of vascular damage and thought to drive atherosclerosis. A method to identify these changes in vivo would be desirable in the clinic. Magnetic resonance imaging (MRI)-based tools and other technologies have enabled a profound understanding of the role of the endothelium in cardiovascular diseases and risk in vivo. There is, however, a need for reproducible and simple approaches for extracting quantifiable data reflective of endothelial damage from a single imaging study. A non-invasive, easy-to-implement, and quantitative MRI workflow was developed to acquire and analyze images that allow the quantification of two imaging biomarkers of arterial endothelial damage (leakiness/permeability and dysfunction). Here, the protocol describes the application of this method in the brachiocephalic artery of atherosclerotic ApoE-/- mice using a clinical MRI scanner. First, late gadolinium enhancement (LGE) and Modified Look-Locker Inversion Recovery (MOLLI) T1 mapping protocols to quantify endothelial leakage using an albumin-binding probe are described. Second, anatomic, and quantitative blood flow sequences to measure endothelial dysfunction, in response to acetylcholine are described. Importantly, the method outlined here allows the acquisition of high-spatial-resolution 3D images with large volumetric coverage enabling accurate segmentation of vessel wall structures to improve inter- and intra-observer variability and to increase reliability and reproducibility. Additionally, it provides quantitative data without the need for high-temporal resolution for complex kinetic modeling, making it model-independent and even allowing for imaging of highly mobile vessels (coronary arteries). Therefore, the approach simplifies and expedites data analysis. Finally, this method can be implemented on different scanners, can be extended to image different arterial beds, and is clinically applicable for use in humans. This method could be used to diagnose and treat patients with atherosclerosis by adopting a precision-medicine approach.

<meta charset="utf8"></head><body>动脉粥样硬化内皮通透性和功能障碍的定量 MRI

We have developed an accurate, non-invasive, and easy-to-use method to quantify endothelial permeability and dysfunction in the arteries using Magnetic Resonance Imaging (MRI), named qMETRIC. This technique enables assessing vascular damage and cardiovascular risk associated with atherosclerosis in preclinical models and humans.

动脉粥样硬化内皮通透性和（不良）功能的定量 MRI

Cardiovascular diseases are the leading causes of death worldwide. A permeable/leaky and dysfunctional endothelium is considered the earliest marker of ...

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 ...

神经科学

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 ...

Cardiac Magnetic Resonance Imaging

Source: Frederick W. Damen and <a href="https://www.jove.com/author/Craig+J._Goergen">Craig J. Goergen</a>, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
In this video, high field, small-bore magnetic resonance imaging (MRI) with physiological monitoring is demonstrated to acquire gated cine loops of the murine cardiovascular system. This procedure provides a basis for assessing left-ventricular function, visualizing vascular networks, and quantifying motion of organs due to respiration. Comparable small animal cardiovascular imaging modalities include high-frequency ultrasound and micro-computed tomography (CT); however, each modality is associated with trade-offs that should be considered. While ultrasound does provide high spatial and temporal resolution, imaging artifacts are common. For example, dense tissue (i.e., the sternum and ribs) can limit imaging penetration depth, and hyperechoic signal at the interface between gas and liquid (i.e., pleura surrounding the lungs) can blur contrast in nearby tissue. Micro-CT in contrast does not suffer from as many in-plane artifacts, but does have lower temporal resolution and limited soft-tissue contrast. Furthermore, micro-CT uses X-ray radiation and often requires the use of contrast agents to visualize vasculature, both of which are known to cause side effects at high doses including radiation damage&#160; and renal injury. Cardiovascular MRI provides a nice compromise between these techniques by negating the need for ionizing radiation and providing the user with the ability to image without contrast agents (although contrast agents are often used for MRI).
This data was acquired with a triggering Fast Low Angle SHot (FLASH) MRI sequence that was gated off of the R-peaks in the cardiac cycle and expiratory plateaus in respiration. These physiological events were monitored through subcutaneous electrodes and a pressure-sensitive pillow that was secured against the abdomen. To ensure the mouse was properly warmed, a rectal temperature probe was inserted and used to control the output of a MRI-safe heating fan. Once the animal was inserted into the bore of the MRI scanner and navigation sequences were run to confirm positioning, the gated FLASH imaging planes were prescribed and data acquired. Overall, high field MRI is a powerful research tool that can provide soft tissue contrast for the study of small animal disease models.

Cardiac MRI: Principle and Imaging

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Source: Frederick W. Damen and Craig J. Goergen, Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana
In this video, high ...

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