心脏磁共振评估疑似心脏血栓:常规和新兴技术
Summary
本文的目的是描述如何使用心脏磁共振来评估和诊断疑似心脏血栓。该方法将描述数据采集以及过程前和过程后协议。
Abstract
我们提出了传统的心脏磁共振(CMR)协议,用于评估疑似血栓,并突出新兴技术。某些磁共振 (MR) 序列上出现质量有助于区分血栓和肿瘤等相互竞争的诊断。血栓的T1和T2信号特性与血红蛋白特性的演变有关。血栓通常不增强后对比管理,这也有助于从肿瘤分化。我们还强调了 T1 映射在血栓评估中新出现的作用,它可以在诊断方面增加另一级别的支持。在任何 CMR 检查之前,患者筛查和面谈对于确保安全性和优化患者舒适度至关重要。技师和患者在检查期间进行有效的沟通,可促进适当的呼吸保持技术和更高质量的图像。量次处理和结构化报告有助于确保放射科医生回答订购服务的问题并有效地传达这些结果。最佳 MR 前安全评估、CMR 检查执行以及检查后处理和报告,允许在评估疑似心脏血栓时提供高质量的放射服务。
Introduction
心脏磁共振(CMR)成像是评价心血管功能和病理学的重要诊断方式。技术进步可缩短采集时间,提高空间和时间分辨率,以及更高质量的组织表征。这些进展在心脏质量评估中特别有用。
回声心动图仍然是心脏质量初始评估的第一线成像模式,特别是关于质量位置、形态和生理影响。然而,超声心动图受到组织特性差、视野受限和操作员依赖图像质量的限制。心脏计算机断层扫描 (CT) 通常用作评估心脏质量的二线成像模式。与其他方式不同,心脏CT的优点包括出色的空间分辨率和卓越的钙化检测能力。心脏CT的主要缺点是患者暴露于电离辐射。其他限制包括时间分辨率降低和软组织对比度分辨率降低。CMR正在成为表征在超声心动图或CT上检测到的心脏质量的宝贵工具。与CT相比,CMR不会使患者暴露在电离辐射下。此外,CMR可用于治疗和手术规划1,2。
血栓是最常见的心脏质量。心脏血栓最常见的位置是左心房和左心房附属,特别是在心房颤动或功能失调的左心室1,3。血栓的诊断对于预防栓塞事件以及确定抗凝的需要非常重要。CMR 可以协助确定血栓的敏锐度。急性血栓通常表现出中间T1和T2加权信号强度相对于心肌,由于大量的含氧血红蛋白。亚急性血栓中的美血红蛋白含量增加,导致T1加权信号强度降低,而T2加权信号强度增加。与慢性血栓,血红蛋白和水被纤维组织取代,导致降低T1和T2加权信号强度1,2,3。
血管组成给出了心脏血栓的内在组织特征,可以通过对比增强的CMR来利用,从而辅助血栓与其他心脏肿瘤的分化4。有组织的血栓不会增强,而真正的心脏病变增强后对比成像由于存在肿瘤内血管3。动脉灌注成像允许实时评估质量内的血管性,并且对于区分血栓和肿瘤至关重要。质量内的灌注也可用于从肿瘤血栓中划定平淡的血栓。与可能受运动伪影约束的其他模式不同,Cine 成像具有优势,实时门控灌注成像提供的时间分辨率提高了检测增强功能 5的灵敏度。
T1 映射是一种 MR 技术,它允许预对比度原生 T1 放松时间和后对比度细胞外体积计算,以检测组织中的病理变化。通过向 CMR 添加定量维度,T1 映射可以帮助区分各种疾病过程和正常心肌。一个新兴的应用是心脏质量的表征和从心脏血栓中描述质量。先前在1.5 T Aera XQ扫描仪上进行的研究已经报告本地T1放松时间最近血栓(911 × 177 ms)和慢性血栓(1,169 × 107 ms)6。其他相关的原生T1放松时间包括脂肪瘤(278 × 29毫秒)、钙化(621 × 218 ms)、黑色素瘤(736 ms)和正常心肌(950 × 21 ms)。这些数据表明,T1映射可以添加定量信息到非对比检查,在设置禁忌到IV高岭土可能是非常有用的6,7。
对比度增强型CMR在检测左心室血栓方面得到了很好的验证。与直胸(分别为23%和96%)和直食管(分别为40%和96%)的超声心动图相比,它为左心室血栓的检测提供了最高的灵敏度和特异性(分别为88%和99%)8.目前,没有大型研究验证CMR在评估心脏其他腔室血栓的效用。
尽管 CMR 与评估心脏质量的其他成像模式具有许多优点,但也存在局限性。CMR 与心脏 CT 一样,依赖于心电图门控。这可能导致严重心律失常患者的伪影和图像退化。当扫描难以遵守呼吸保持要求的患者时,图像质量也会降低。然而,更快的采集时间和呼吸门控技术允许在自由呼吸期间获得高质量的图像。某些植入设备的存在是CMR的禁忌,并作为一个主要缺点,虽然MR兼容植入设备的数量正在增加1,2。
总之,特定的CMR序列可用于开发用于评估疑似心脏血栓的专用MR成像方案。此处介绍的方法将提供用于评估疑似血栓的 CMR 数据的说明。将讨论程序前筛选、序列选择、故障排除、后处理、体积分析和报告生成。
Protocol
Representative Results
Discussion
随着诊断成像的质量和频率的不断提高,在为不相关的适应症进行成像时,发现偶然的心脏质量并不罕见。心脏肿大的患者通常是无症状的,如果存在,症状通常是非特异性的。
心脏血栓的诊断不仅对区分血栓与良性或恶性心脏肿瘤很重要,而且对于确定抗凝和预防栓塞事件1的必要性也具有重要意义。在疑似心脏血栓患者中,使用特定方案的单一成像模式选项可以?…
Declarações
The authors have nothing to disclose.
Acknowledgements
作者承认H.LeeMoffitt癌症中心和研究所的诊断成像部门的支持。
Materials
| MRI Scanner | Siemens Healthcare Erlangen, Germany |
Magnetom Aera 1.5 Tesla | MRI scanner that will be used for the demonstration |
| Post processing software | Medis The Netherlands |
Qmass software | post processing software for ventricular volumetric and T1 mapping analysis |
| Scanner processing software | Siemens Healthcare Erlangen, Germany |
Myomaps | Scanner sequence package and post processing software |
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