Department of Bioengineering, UC Berkeley, Berkeley CA, United States of America.
Berkeley Pre-clinical Imaging Core, UC Berkeley, Berkeley CA, United States of America.
Phys Med Biol. 2021 Jul 16;66(14). doi: 10.1088/1361-6560/ac0e78.
Cardiac chemical exchange saturation transfer-magnetic resonance imaging (CEST-MRI) has been used to probe levels of various metabolites that provide insight into myocardial structure and function. However, imaging of the heart using CEST-MRI is prolonged by the need to repeatedly acquire multiple images for a full Z-spectrum and to perform saturation and acquisition around cardiac and respiratory cycles. Compressed sensing (CS) reconstruction of sparse data enables accelerated acquisition, but reconstruction artifacts may bias subsequently derived measures of CEST contrast. In this study, we examine the impact of CS reconstruction of increasingly under-sampled cardiac CEST-MRI data on subsequent CEST contrasts of amine-containing metabolites and amide-containing proteins. Cardiac CEST-MRI data sets were acquired in six mice using low and high RF saturation for single and dual contrast generation, respectively. CEST-weighted images were reconstructed using CS methods at 2-5× levels of under-sampling. CEST contrasts were derived from corresponding Z-spectra and the impact of accelerated imaging on accuracy was assessed via analysis of variance. CS reconstruction preserved myocardial signal to noise ratio as compared to conventional reconstruction. However, greater absolute error and distribution of derived contrasts was observed with increasing acceleration factors. The results from this study indicate that acquisition of radial cardiac CEST-MRI data can be modestly, but meaningfully, accelerated via CS reconstructions with little error in CEST contrast quantification.
心脏化学交换饱和传递磁共振成像（CEST-MRI）已被用于探测各种代谢物的水平，这些代谢物可深入了解心肌的结构和功能。然而，CEST-MRI 对心脏的成像需要反复采集多个图像以获得完整的 Z 谱，并围绕心脏和呼吸周期进行饱和和采集，因此成像时间延长。稀疏数据的压缩感知（CS）重建可实现加速采集，但重建伪影可能会影响随后衍生的 CEST 对比测量值。在这项研究中，我们研究了 CS 重建在稀疏度逐渐增加的心脏 CEST-MRI 数据对后续含胺代谢物和酰胺蛋白的 CEST 对比的影响。使用低和高 RF 饱和度分别为单和双对比生成，在六只小鼠中采集心脏 CEST-MRI 数据集。使用 CS 方法在 2-5 倍的欠采样水平重建 CEST 加权图像。从相应的 Z 谱中得出 CEST 对比，并通过方差分析评估加速成像对准确性的影响。CS 重建与传统重建相比保持了心肌的信噪比。然而，随着加速因子的增加，观察到更大的绝对误差和衍生对比的分布。这项研究的结果表明，通过 CS 重建可以适度但有意义地加速心脏 CEST-MRI 数据的采集，并且 CEST 对比量化的误差很小。
