Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands.
Invest Radiol. 2012 Dec;47(12):697-704. doi: 10.1097/RLI.0b013e31826dc174.
Magnetic resonance imaging (MRI) of the vessel wall enables determination of luminal area, vessel wall thickness, and atherosclerotic plaque characteristics. For clinical application, high spatial resolution, derived from optimal signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), is paramount. Vessel wall MRI is expected to benefit from higher magnetic field strength. Therefore, the purposes of the present study were to develop an ultrahigh-field 7-T MRI hardware and protocols for vessel wall imaging of the carotid artery and to compare quantitative parameters of vessel wall morphology and image quality between 3-T and 7-T MRI.
Eighteen volunteers (11 men and 7 women; mean [SD] age, 29 [7] years) underwent MRI examinations at 7 T (using a custom-built surface transmit/receive coil of 15-cm diameter) and at 3 T (using a commercial phased-array coil with 2 flexible oval elements, 14 × 17 cm each). Magnetic resonance imaging of the left common carotid artery vessel wall was performed at 7 T with identical in-plane resolution as that of 3-T MRI (0.46 × 0.46 mm), providing transverse T1- and T2-weighted images. Blinded analysis of morphologic measurements (luminal area and vessel wall area), SNR for vessel wall (SNRVW), and the CNR between the lumen and the vessel wall were compared between 7 and 3 T.
Morphologic carotid vessel wall measurements were comparable between 7 and 3 T for both T1-weighted images (luminal area: intraclass correlation [ICC], 0.81 and vessel wall area: ICC, 0.84) and T2-weighted images (luminal area: ICC, 0.97 and vessel wall area: ICC, 0.92). At 7 T, SNRVW and CNR were significantly higher compared with 3-T MRI for both T1- (P < 0.001) and T2-weighted images (P < 0.05), with gain factors ranging from 1.3 to 3.6.
Ultrahigh-field 7-T MR carotid vessel wall imaging is feasible. 7-T MRI of the common carotid artery has comparable accuracy for determining luminal area and vessel wall area and has improved SNRVW and CNR compared with 3-T MRI. Therefore, ultrahigh-field 7-T vessel wall MRI may enable a more detailed assessment of plaque morphology.
磁共振血管壁成像（MRI）可确定管腔面积、血管壁厚度和粥样斑块特征。为了临床应用，高空间分辨率至关重要，它源于最佳的信噪比（SNR）和对比噪声比（CNR）。血管壁 MRI 有望受益于更高的磁场强度。因此，本研究旨在开发超高场 7T 磁共振血管壁成像的硬件和协议，并比较颈动脉 3T 和 7T MRI 的血管壁形态和图像质量的定量参数。
18 名志愿者（男 11 名，女 7 名；平均[标准差]年龄 29[7]岁）分别在 7T（使用直径 15cm 的定制表面发射/接收线圈）和 3T（使用 2 个柔性椭圆形元件的商用相控阵线圈，每个元件长 14cm、宽 17cm）上进行 MRI 检查。在 7T 下对左颈总动脉血管壁进行磁共振成像，与 3T MRI 的平面内分辨率相同（0.46×0.46mm），提供横向 T1 加权和 T2 加权图像。在 7T 和 3T 之间比较形态学测量（管腔面积和血管壁面积）、血管壁 SNR（SNRVW）和管腔与血管壁之间的 CNR 的盲法分析。
在 T1 加权图像（管腔面积：组内相关系数[ICC]，0.81 和血管壁面积：ICC，0.84）和 T2 加权图像（管腔面积：ICC，0.97 和血管壁面积：ICC，0.92）中，7T 和 3T 的颈动脉血管壁形态学测量结果具有可比性。与 3T MRI 相比，7T 的 SNRVW 和 CNR 在 T1 加权（P＜0.001）和 T2 加权（P＜0.05）图像中均显著升高，增益因子范围为 1.3 至 3.6。
超高场 7T 磁共振颈动脉血管壁成像可行。7T MRI 对管腔面积和血管壁面积的测定具有可比性，与 3T MRI 相比，SNRVW 和 CNR 有所提高。因此，超高场 7T 血管壁 MRI 可能使斑块形态的评估更详细。
