Stabinska Julia, Müller-Lutz Anja, Wittsack Hans-Jörg, Tell Christian, Rump Lars Christian, Ertas Neslihan, Antoch Gerald, Ljimani Alexandra
Department of Diagnostic and Interventional Radiology, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany.
Department of Nephrology, Medical Faculty, Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany.
Magn Reson Imaging. 2022 Jul;90:61-69. doi: 10.1016/j.mri.2022.04.004. Epub 2022 Apr 25.
To assess the performance of two point (2-pt) Dixon-based chemical exchange saturation transfer (CEST) imaging for fat suppression in renal transplant patients.
The 2-pt Dixon-based CEST MRI was validated in an egg-phantom and in fourteen renal transplant recipients (5 females and 9 males; age range: 23-78 years; mean age: 51 ± 16.8). All CEST experiments were performed on a 3 T clinical MRI scanner using a dual-echo CEST sequence. The 2-pt Dixon technique was applied to generate water-only CEST images at different frequency offsets, which were further used to calculate the z-spectra. The magnetization transfer ratio asymmetry (MTR) values in the frequency ranges of hydroxyl, amine and amide protons were estimated in the renal cortex and medulla.
Results of the in vitro experiments suggest that the 2-pt Dixon technique enables effective fat peak removal and does not introduce additional asymmetries to the z-spectrum. Accordingly, our results in vivo show that the fat-corrected amide proton transfer (APT) effect in the kidney is significantly higher compared to that obtained from the CEST data acquired close to the in-phase condition both in the renal cortex (-0.1 [0.7] vs. -0.7 [1.2], P = 0.029) and medulla (0.3 [0.8] vs. 0.01 [1.3], P = 0.049), indicating that the 2-pt Dixon-based CEST method increases the specificity of the APT contrast by correcting the fat-induced artifacts.
Combination of the dual-echo CEST acquisition with Dixon post-processing provides effective water-fat separation, allowing more accurate quantification of the APT CEST effect in the transplanted kidney.
评估基于两点（2-pt）狄克逊的化学交换饱和转移（CEST）成像在肾移植患者脂肪抑制中的性能。
基于2-pt狄克逊的CEST MRI在鸡蛋模型和14名肾移植受者（5名女性和9名男性；年龄范围：23 - 78岁；平均年龄：51±16.8）中进行验证。所有CEST实验均在3T临床MRI扫描仪上使用双回波CEST序列进行。应用2-pt狄克逊技术在不同频率偏移下生成仅水的CEST图像，这些图像进一步用于计算z谱。在肾皮质和髓质中估计羟基、胺和酰胺质子频率范围内的磁化转移率不对称（MTR）值。
体外实验结果表明，2-pt狄克逊技术能够有效去除脂肪峰，且不会给z谱引入额外的不对称性。因此，我们的体内结果显示，与从接近同相条件下采集的CEST数据获得的结果相比，肾脏中脂肪校正后的酰胺质子转移（APT）效应在肾皮质（-0.1 [0.7]对-0.7 [1.2]，P = 0.029）和髓质（0.3 [0.8]对0.01 [1.3]，P = 0.049）中均显著更高，表明基于2-pt狄克逊的CEST方法通过校正脂肪诱导的伪影提高了APT对比的特异性。
双回波CEST采集与狄克逊后处理相结合可实现有效的水脂分离，从而更准确地量化移植肾中的APT CEST效应。
