Department of Pediatric Radiology, Stanford University School of Medicine, 725 Welch Rd, Room 1679, Stanford, CA 94305-5913, USA.
Radiology. 2010 Aug;256(2):607-16. doi: 10.1148/radiol.10091218. Epub 2010 Jun 7.
To develop a method that combines parallel imaging and compressed sensing to enable faster and/or higher spatial resolution magnetic resonance (MR) imaging and show its feasibility in a pediatric clinical setting.
Institutional review board approval was obtained for this HIPAA-compliant study, and informed consent or assent was given by subjects. A pseudorandom k-space undersampling pattern was incorporated into a three-dimensional (3D) gradient-echo sequence; aliasing then has an incoherent noiselike pattern rather than the usual coherent fold-over wrapping pattern. This k-space-sampling pattern was combined with a compressed sensing nonlinear reconstruction method that exploits the assumption of sparsity of medical images to permit reconstruction from undersampled k-space data and remove the noiselike aliasing. Thirty-four patients (15 female and 19 male patients; mean age, 8.1 years; range, 0-17 years) referred for cardiovascular, abdominal, and knee MR imaging were scanned with this 3D gradient-echo sequence at high acceleration factors. Obtained k-space data were reconstructed with both a traditional parallel imaging algorithm and the nonlinear method. Both sets of images were rated for image quality, radiologist preference, and delineation of specific structures by two radiologists. Wilcoxon and symmetry tests were performed to test the hypothesis that there was no significant difference in ratings for image quality, preference, and delineation of specific structures.
Compressed sensing images were preferred more often, had significantly higher image quality ratings, and greater delineation of anatomic structures (P < .001) than did images obtained with the traditional parallel reconstruction method.
A combination of parallel imaging and compressed sensing is feasible in a clinical setting and may provide higher resolution and/or faster imaging, addressing the challenge of delineating anatomic structures in pediatric MR imaging.
开发一种结合并行成像和压缩感知的方法，实现更快和/或更高空间分辨率的磁共振成像，并在儿科临床环境中验证其可行性。
本研究符合 HIPAA 规定，通过了机构审查委员会的批准，并获得了研究对象的知情同意或同意。在三维（3D）梯度回波序列中引入伪随机的 K 空间欠采样模式；混叠后会呈现出非相干的噪声样图案，而不是通常的相干折叠包裹图案。这种 K 空间采样模式与压缩感知非线性重建方法相结合，利用医学图像稀疏性的假设，允许从欠采样的 K 空间数据中进行重建，并去除噪声样的混叠。对 34 例（15 例女性，19 例男性；平均年龄 8.1 岁；范围 0-17 岁）因心血管、腹部和膝关节磁共振成像而就诊的患者进行了此 3D 梯度回波序列的高加速因子扫描。使用传统的并行成像算法和非线性方法对获得的 K 空间数据进行重建。两位放射科医生对两组图像的质量、放射科医生的偏好以及特定结构的勾画进行了评分。使用 Wilcoxon 符号秩检验和对称性检验来检验图像质量、偏好和特定结构勾画的评分没有显著差异的假设。
压缩感知图像更受青睐，图像质量评分显著更高，对解剖结构的勾画也更好（P<0.001），优于传统并行重建方法获得的图像。
并行成像和压缩感知的结合在临床环境中是可行的，可能提供更高的分辨率和/或更快的成像速度，解决儿科磁共振成像中勾画解剖结构的挑战。
