Vanderbilt University Institute of Imaging Science, Nashville, Tennessee.
Department of Radiology and Radiological Sciences, Vanderbilt University Medical Center, Nashville, Tennessee.
NMR Biomed. 2021 Feb;34(2):e4437. doi: 10.1002/nbm.4437. Epub 2020 Dec 7.
In chemical exchange saturation transfer (CEST) imaging, the signal at 2.6 ppm from the water resonance in muscle has been assigned to phosphocreatine (PCr). However, this signal has limited specificity for PCr since the signal is also sensitive to exchange with protein and macromolecular protons when using some conventional quantification methods, and will vary with changes in the water longitudinal relaxation rate. Correcting for these effects while maintaining reasonable acquisition times is challenging. As an alternative approach to overcome these problems, here we evaluate chemical exchange rotation transfer (CERT) imaging of PCr in muscle at 9.4 T. Specifically, the CERT metric, AREX at 2.6 ppm, was measured in solutions containing the main muscle metabolites, in tissue homogenates with controlled PCr content, and in vivo in rat leg muscles. PCr dominates CERT metrics around 2.6 ppm (although with nontrivial confounding baseline contributions), indicating that CERT is well-suited to PCr specific imaging, and has the added benefit of requiring a relatively small number of acquisitions.
在化学交换饱和转移（CEST）成象中，肌肉中来自水共振的 2.6ppm 处的信号被分配给磷酸肌酸（PCr）。然而，由于当使用一些常规定量方法时，该信号对蛋白质和大分子质子的交换也很敏感，并且会随水纵向弛豫率的变化而变化，因此该信号对 PCr 的特异性有限。在保持合理采集时间的同时纠正这些影响具有挑战性。作为克服这些问题的替代方法，我们在这里在 9.4T 下评估肌肉中 PCr 的化学交换旋转转移（CERT）成象。具体而言，在含有主要肌肉代谢物的溶液、具有受控 PCr 含量的组织匀浆以及在大鼠腿部肌肉的体内，测量了 CERT 度量，即 2.6ppm 处的 AREX。PCr 在 2.6ppm 左右主导 CERT 度量（尽管存在相当大的混杂基线贡献），表明 CERT 非常适合 PCr 特异性成象，并且具有相对较少采集次数的优点。
