Dyverfeldt Petter, Deshpande Vibhas S, Kober Tobias, Krueger Gunnar, Saloner David
Department of Radiology & Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
J Magn Reson Imaging. 2014 Jul;40(1):214-20. doi: 10.1002/jmri.24389. Epub 2013 Nov 13.
To develop a framework for prospective free-induction decay (FID)-based navigator gating for suppression of motion artifacts in carotid magnetic resonance imaging (MRI) and to assess its capability in vivo.
An FID-navigator, comprising a spatially selective low flip-angle sinc-pulse followed by an analog-to-digital converter (ADC) readout, was added to a conventional turbo spin-echo (TSE) sequence. Real-time navigator processing delivered accept/reject-and-reacquire decisions to the sequence. In this Institutional Review Board (IRB)-approved study, seven volunteers were scanned with a 2D T2-weighted TSE sequence. A reference scan with volunteers instructed to minimize motion as well as nongated and gated scans with volunteers instructed to perform different motion tasks were performed in each subject. Multiple image quality measures were employed to quantify the effect of gating.
There was no significant difference in lumen-to-wall sharpness (2.3 ± 0.3 vs. 2.3 ± 0.4), contrast-to-noise ratio (CNR) (9.0 ± 2.0 vs. 8.5 ± 2.0), or image quality score (3.1 ± 0.9 vs. 2.6 ± 1.2) between the reference and gated images. For images acquired during motion, all image quality measures were higher (P < 0.05) in the gated compared to nongated images (sharpness: 2.3 ± 0.4 vs. 1.8 ± 0.5, CNR: 8.5 ± 2.0 vs. 7.2 ± 2.0, score: 2.6 ± 1.2 vs. 1.8 ± 1.0).
Artifacts caused by the employed motion tasks deteriorated image quality in the nongated scans. These artifacts were alleviated with the proposed FID-navigator.
开发一种基于前瞻性自由感应衰减（FID）的导航门控框架，以抑制颈动脉磁共振成像（MRI）中的运动伪影，并评估其在体内的性能。
将一个FID导航器添加到传统的快速自旋回波（TSE）序列中，该导航器由一个空间选择性低翻转角 sinc 脉冲和一个模数转换器（ADC）读出组成。实时导航器处理为序列提供接受/拒绝和重新采集的决策。在这项经机构审查委员会（IRB）批准的研究中，7名志愿者接受了二维T2加权TSE序列扫描。对每位受试者进行了一次要求志愿者尽量减少运动的参考扫描，以及要求志愿者执行不同运动任务的非门控和门控扫描。采用多种图像质量指标来量化门控的效果。
参考图像和门控图像之间在管腔与管壁清晰度（2.3±0.3对2.3±0.4）、对比噪声比（CNR）（9.0±2.0对8.5±2.0）或图像质量评分（3.1±0.9对2.6±1.2）方面无显著差异。对于运动期间采集的图像，与非门控图像相比，门控图像的所有图像质量指标均更高（P<0.05）（清晰度：2.3±0.4对1.8±0.5，CNR：8.5±2.0对7.2±2.0，评分：2.6±1.2对1.8±1.0）。
所采用的运动任务导致的伪影在非门控扫描中降低了图像质量。所提出的FID导航器减轻了这些伪影。
