Sartoretti Thomas, Reischauer Carolin, Sartoretti Elisabeth, Binkert Christoph, Najafi Arash, Sartoretti-Schefer Sabine
Institut für Radiologie, Kantonsspital Winterthur, Brauerstrasse 15, 8401, Winterthur, Switzerland.
Insights Imaging. 2018 Dec;9(6):1107-1115. doi: 10.1007/s13244-018-0668-4. Epub 2018 Nov 8.
Various techniques have been proposed which aim at scan time reduction and/or at improved image quality by increasing the spatial resolution. Compressed sensing (CS) takes advantage of the fact that MR images are usually sparse in some transform domains and recovers this sparse representation from undersampled data. CS may be combined with parallel imaging such as sensitivity encoding (SENSE), hereafter referred to as Compressed SENSE, to further accelerate image acquisition since both techniques rely on different ancillary information. In practice, Compressed SENSE may reduce scan times of two-dimensional (2D) and three-dimensional (3D) scans by up to 50% depending on the sequence acquired and it works on 1.5-T or 3-T scanners. Compressed SENSE may be applied to 2D and 3D sequences in various anatomies and image contrasts. Image artefacts (i.e. motion, metal and flow artefacts, susceptibility artefacts) frequently appear on magnetic resonance images. The Compressed SENSE technique may cause special artefacts, which might influence image assessment if they go undetected by imaging readers. Our institution has been using Compressed SENSE for over half a year, both in a neuroradiological setting and for musculoskeletal examinations. So far, three special image artefacts-called the wax-layer artefact, the streaky-linear artefact and the starry-sky artefact-have been encountered and we aim to review these main artefacts appearing in sequences acquired with Compressed SENSE. TEACHING POINTS: • Compressed SENSE combines compressed sensing and SENSE technique. • Compressed SENSE permits scan time reduction and increases spatial image resolution. • Images acquired with Compressed SENSE may present with special artefacts. • Knowledge of artefacts is necessary for reliable image assessment.
人们已经提出了各种技术，旨在通过提高空间分辨率来减少扫描时间和/或改善图像质量。压缩感知（CS）利用了磁共振图像在某些变换域通常是稀疏的这一事实，并从欠采样数据中恢复这种稀疏表示。CS可以与并行成像（如灵敏度编码（SENSE））相结合，以下简称为压缩感知（Compressed SENSE），以进一步加速图像采集，因为这两种技术依赖于不同的辅助信息。在实践中，根据所采集的序列，压缩感知可以将二维（2D）和三维（3D）扫描的时间减少多达50%，并且它适用于1.5-T或3-T扫描仪。压缩感知可以应用于各种解剖结构和图像对比度的2D和3D序列。图像伪影（即运动、金属和流动伪影、磁化率伪影）经常出现在磁共振图像上。压缩感知技术可能会导致特殊伪影，如果成像阅片者未检测到这些伪影，可能会影响图像评估。我们机构在神经放射学和肌肉骨骼检查中使用压缩感知已经超过半年了。到目前为止，已经遇到了三种特殊的图像伪影，即蜡层伪影、条纹状线性伪影和星空伪影，我们旨在回顾这些在压缩感知采集的序列中出现的主要伪影。教学要点：• 压缩感知结合了压缩传感和SENSE技术。• 压缩感知可以减少扫描时间并提高空间图像分辨率。• 用压缩感知采集的图像可能会出现特殊伪影。• 了解伪影对于可靠的图像评估是必要的。
