Department of Electrical Engineering, Stanford University, Stanford, California, USA.
Global MR Applications and Workflow, GE Healthcare, Menlo Park, California, USA.
J Magn Reson Imaging. 2018 Apr;47(4):954-966. doi: 10.1002/jmri.25853. Epub 2017 Sep 14.
It is highly desirable in clinical abdominal MR scans to accelerate single-shot fast spin echo (SSFSE) imaging and reduce blurring due to T decay and partial-Fourier acquisition.
To develop and investigate the clinical feasibility of wave-encoded variable-density SSFSE imaging for improved image quality and scan time reduction.
Prospective controlled clinical trial.
With Institutional Review Board approval and informed consent, the proposed method was assessed on 20 consecutive adult patients (10 male, 10 female, range, 24-84 years).
FIELD STRENGTH/SEQUENCE: A wave-encoded variable-density SSFSE sequence was developed for clinical 3.0T abdominal scans to enable high acceleration (3.5×) with full-Fourier acquisitions by: 1) introducing wave encoding with self-refocusing gradient waveforms to improve acquisition efficiency; 2) developing self-calibrated estimation of wave-encoding point-spread function and coil sensitivity to improve motion robustness; and 3) incorporating a parallel imaging and compressed sensing reconstruction to reconstruct highly accelerated datasets.
Image quality was compared pairwise with standard Cartesian acquisition independently and blindly by two radiologists on a scale from -2 to 2 for noise, contrast, confidence, sharpness, and artifacts. The average ratio of scan time between these two approaches was also compared.
A Wilcoxon signed-rank tests with a P value under 0.05 considered statistically significant.
Wave-encoded variable-density SSFSE significantly reduced the perceived noise level and improved the sharpness of the abdominal wall and the kidneys compared with standard acquisition (mean scores 0.8, 1.2, and 0.8, respectively, P < 0.003). No significant difference was observed in relation to other features (P = 0.11). An average of 21% decrease in scan time was achieved using the proposed method.
Wave-encoded variable-density sampling SSFSE achieves improved image quality with clinically relevant echo time and reduced scan time, thus providing a fast and robust approach for clinical SSFSE imaging.
1 Technical Efficacy: Stage 6 J. Magn. Reson. Imaging 2018;47:954-966.
在临床腹部磁共振扫描中，加速单次激发快速自旋回波（SSFSE）成像并减少 T 衰减和部分傅立叶采集引起的模糊是非常理想的。
开发并研究用于改善图像质量和减少扫描时间的基于波编码可变密度 SSFSE 成像的临床可行性。
前瞻性对照临床试验。
经机构审查委员会批准并获得知情同意，该方法在 20 名连续成年患者（10 名男性，10 名女性，年龄 24-84 岁）上进行了评估。
磁场强度/序列：为临床 3.0T 腹部扫描开发了一种基于波编码的可变密度 SSFSE 序列，通过以下方式实现高加速（3.5×）和全傅立叶采集：1）引入具有自聚焦梯度波形的波编码以提高采集效率；2）开发自校准的波编码点扩散函数和线圈灵敏度估计以提高运动稳健性；3）结合并行成像和压缩感知重建来重建高度加速的数据集。
两位放射科医生独立、盲法地对图像质量进行两两比较，评分范围为-2 到 2，用于噪声、对比度、置信度、锐度和伪影。还比较了这两种方法的扫描时间的平均比值。
Wilcoxon 符号秩检验，P 值<0.05 为统计学显著。
与标准采集相比，基于波编码的可变密度 SSFSE 显著降低了腹部壁和肾脏的感知噪声水平，并提高了锐度（平均评分分别为 0.8、1.2 和 0.8，P<0.003）。在其他特征方面没有观察到显著差异（P=0.11）。使用该方法平均可减少 21%的扫描时间。
基于波编码的可变密度采样 SSFSE 在具有临床相关回波时间的情况下实现了更好的图像质量，并减少了扫描时间，从而为临床 SSFSE 成像提供了一种快速而稳健的方法。
1 技术功效：第 6 阶段 J. 磁共振成像 2018；47:954-966。
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