Hinton Denise P, Cury Ricardo C, Chan Raymond C, Wald Lawrence L, Sherwood Jane B, Furie Karen L, Pitts John T, Schmitt Franz
MGH/MIT/HMS, Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA.
Eur J Radiol. 2006 Mar;57(3):403-11. doi: 10.1016/j.ejrad.2005.12.028. Epub 2006 Jan 26.
The aim of this study was to evaluate our preliminary experience at 3.0 T with imaging of the carotid bifurcation in healthy and atherosclerotic subjects. Application at 3.0 T is motivated by the signal-to-noise gain for improving spatial resolution and reducing signal averaging requirements.
We utilized a dual phased array coil and applied 2D, 3D time of flight (TOF) and turbo spin echo (TSE) sequences with comparison of two lumen signal suppression methods for black blood (BB) TSE imaging including double inversion preparation (DIR) and spatial presaturation pulses. The signal-to-noise ratios (SNR) of healthy carotid vessel walls were compared in 2D and 3D BB TSE acquisitions. The bright and black blood multi-contrast exam was demonstrated for a complex carotid plaque.
Contrast-to-noise (CNR) greater than 150 was achieved between the lumen and suppressed background for 3D TOF. For BB, both methods provided sufficient lumen signal suppression but slight residual flow artifacts remained at the bifurcation level. As expected 3D TSE images had higher SNR compared to 2D, but increased motion sensitivity is a significant issue for 3D at high field. For multi-contrast imaging of atherosclerotic plaque, fibrous, calcified and lipid components were resolved. The CNR ratio of fibrous (bright on PDW, T2W) and calcified (dark in T1W, T2W, PDW) plaque components was maximal in the T2W images. The 3D TOF angiogram indicating a 40% stenosis was complemented by 3D multi-planar reformat of BB images that displayed plaque extent. Detection of intimal thickening, the earliest change associated with atherosclerotic progression was observed in BB PDW images at 3.0 T.
High SNR and CNR images have been demonstrated for the healthy and diseased carotid. Improvements in RF coils along with pulse sequence optimization, and evaluation of endogenous and exogenous contrast mechanisms will further enhance carotid imaging at 3.0T.
本研究的目的是评估我们在3.0T磁场下对健康和动脉粥样硬化受试者颈动脉分叉处成像的初步经验。在3.0T磁场下进行成像的动机是信噪比的提高，这有助于提高空间分辨率并减少信号平均的要求。
我们使用了一个双相控阵线圈，并应用了二维、三维时间飞跃（TOF）和快速自旋回波（TSE）序列，同时比较了两种用于黑血（BB）TSE成像的管腔信号抑制方法，包括双反转准备（DIR）和空间预饱和脉冲。比较了二维和三维BB TSE采集中健康颈动脉血管壁的信噪比（SNR）。展示了一个复杂颈动脉斑块的亮血和黑血多对比检查。
三维TOF成像在管腔和被抑制的背景之间实现了大于150的对比噪声比（CNR）。对于BB成像，两种方法都提供了足够的管腔信号抑制，但在分叉水平仍有轻微的残余血流伪影。正如预期的那样，三维TSE图像的SNR高于二维图像，但在高场强下，三维图像的运动敏感性增加是一个重要问题。对于动脉粥样硬化斑块的多对比成像，可以分辨出纤维、钙化和脂质成分。纤维（在质子密度加权像、T2加权像上呈亮信号）和钙化（在T1加权像、T2加权像、质子密度加权像上呈暗信号）斑块成分的CNR比值在T2加权像上最大。三维TOF血管造影显示有40%的狭窄，同时三维BB图像的多平面重组显示了斑块范围，对其进行了补充。在3.0T磁场下的BB质子密度加权像中观察到了内膜增厚，这是与动脉粥样硬化进展相关的最早变化。
已证明在健康和病变的颈动脉中可以获得高SNR和CNR的图像。射频线圈的改进以及脉冲序列的优化，以及对内源性和外源性对比机制的评估，将进一步提高3.0T磁场下的颈动脉成像质量。
