de Rotte Alexandra A J, Koning Wouter, Truijman Martine T B, den Hartog Anne G, Bovens Sandra M, Vink Aryan, Sepehrkhouy Shahrzad, Zwanenburg Jaco J M, Klomp Dennis W J, Pasterkamp Gerard, Moll Frans L, Luijten Peter R, Hendrikse Jeroen, de Borst Gert Jan
From the *Department of Radiology, University Medical Center Utrecht, Utrecht; Departments of †Radiology, and ‡Clinical Neurophysiology, §Cardiovascular Research Institute Maastricht, University Medical Center Maastricht, Maastricht; ∥Department of Vascular Surgery, University Medical Center Utrecht, Utrecht, the Netherlands; ¶Department of Bioengineering, Imperial College London, London, United Kingdom; Departments of #Pathology, and **Experimental Cardiology, University Medical Center Utrecht, Utrecht, the Netherlands.
Invest Radiol. 2014 Nov;49(11):749-57. doi: 10.1097/RLI.0000000000000079.
The objective of this study was to assess the feasibility of carotid vessel wall imaging at 7.0 for T magnetic resonance imaging (MRI) in a series of patients with a symptomatic greater than 70% stenosis of the internal carotid artery.
First, a series of 6 healthy volunteers were scanned at 3.0 T and 7.0 T MRI to perform a signal-to-noise ratio comparison between these 2 field strengths. Second, in patients with a greater than 70% stenosed carotid artery, a 7.0 T MRI protocol, consisting of a dual-echo turbo spin echo sequence (echo times of 45 and 150 milliseconds) and a T1-weighted turbo spin echo sequence, was obtained. Lumen and vessel wall were delineated for interobserver and intraobserver reproducibility, and signal intensity distribution in the most severely stenosed part of the internal carotid artery was correlated with different plaque components on histopathologic findings.
The mean (SD) signal-to-noise ratio in the vessel wall was 42 (12) at 7.0 T and 24 (4) at 3.0 T. Nineteen patients were included, but technical issues yielded carotid MRI data of 14 patients available for the final analysis. Of these patients, 4 were diagnosed with stroke, 7 were diagnosed with a transient ischemic attack, and 3 were diagnosed with amaurosis fugax. Intraclass correlation coefficient of the agreements of lumen and vessel wall determination between 2 observers and between the repeated measures of 1 observer were above 0.80 in both 3.0 T and 7.0 T data sets of the healthy volunteers and also in the 7.0 T data set of the patients. Signal hyperintensity in the 7.0 T magnetic resonance images was inversely proportional to calcification. Other correlations between plaque components and signal intensity could not be confirmed.
This first series of patients with carotid atherosclerotic plaque who were scanned at 7.0 T MRI shows that 7.0 T MRI enables to adequately determine lumen and vessel wall areas. Signal hyperintensity in these 7.0 T magnetic resonance images was inversely proportional to calcification. However, at this stage, no other correlations between histologic findings and vessel wall contrast were found. Implementation of in vivo high-resolution 7.0 T MRI of plaque components for risk stratification remains challenging. Future development of hardware and software is still needed to attain a more robust setup and to enable complete plaque characterization, similar to what is currently possible with multiple MRI sequences at 1.5 T and 3.0 T MRI.
本研究的目的是评估在一系列有症状的颈内动脉狭窄大于70%的患者中，使用7.0 T磁共振成像（MRI）进行颈动脉血管壁成像的可行性。
首先，对6名健康志愿者分别进行3.0 T和7.0 T MRI扫描，以比较这两种场强下的信噪比。其次，对于颈内动脉狭窄大于70%的患者，采用一种7.0 T MRI方案，该方案包括一个双回波快速自旋回波序列（回波时间分别为45和150毫秒）和一个T1加权快速自旋回波序列。对管腔和血管壁进行勾画，以评估观察者间和观察者内的可重复性，并将颈内动脉最严重狭窄部位的信号强度分布与组织病理学发现的不同斑块成分相关联。
7.0 T时血管壁的平均（标准差）信噪比为42（12），3.0 T时为24（4）。共纳入19例患者，但由于技术问题，最终分析仅获得了14例患者的颈动脉MRI数据。其中，4例诊断为中风，7例诊断为短暂性脑缺血发作，3例诊断为一过性黑矇。在健康志愿者的3.0 T和7.0 T数据集以及患者的7.0 T数据集中，两名观察者之间以及一名观察者重复测量之间管腔和血管壁测定的组内相关系数均高于0.80。7.0 T磁共振图像中的信号高强化与钙化呈负相关。斑块成分与信号强度之间的其他相关性未得到证实。
这第一组接受7.0 T MRI扫描的颈动脉粥样硬化斑块患者表明，7.0 T MRI能够充分确定管腔和血管壁面积。这些7.0 T磁共振图像中的信号高强化与钙化呈负相关。然而，在现阶段，未发现组织学发现与血管壁对比度之间的其他相关性。将斑块成分的体内高分辨率7.0 T MRI用于风险分层仍具有挑战性。未来仍需要硬件和软件的进一步发展，以实现更强大的设置并能够完整地对斑块进行特征描述——类似于目前在1.5 T和3.0 T MRI下使用多个MRI序列所能实现的那样。
