Quantitative Multinuclear Musculoskeletal Imaging Group, Center for Biomedical Imaging, Department of Radiology, New York University Langone Medical Center, New York, NY 10016, USA.
Sci Rep. 2013;3:1707. doi: 10.1038/srep01707.
The development of chemical exchange saturation transfer (CEST) has led to the establishment of new contrast mechanisms in magnetic resonance imaging, which serve as enablers for advanced molecular imaging strategies. Macromolecules in tissues and organs often give rise to broad and asymmetric exchange effects, called magnetization transfer (MT) effects, which can mask the CEST contrast of interest. We show here that the saturation of these macromolecular pools simultaneously at two distinct frequencies can level out the asymmetric MT effects, thus allowing one to isolate the CEST effects in vivo. For the first time, clean CEST contrast for glycosaminoglycans (gagCEST) in cartilage in the human knee joint is presented. In addition, the method allows one to clearly demarcate glycosaminoglycan measurements from cartilage and synovial fluid regions. This uniform-MT CEST methodology has wide applicability in in vivo molecular imaging (such as brain, skeletal muscle, etc).
化学交换饱和传递（CEST）的发展导致磁共振成像中建立了新的对比机制，这些机制为先进的分子成像策略提供了支持。组织和器官中的大分子通常会产生广泛而不对称的交换效应，称为磁化转移（MT）效应，这些效应可能会掩盖感兴趣的 CEST 对比。我们在这里表明，同时在两个不同频率下对这些大分子池进行饱和可以使不对称的 MT 效应趋于平坦，从而可以在体内分离 CEST 效应。首次在人体膝关节软骨中展示了糖胺聚糖（gagCEST）的清晰 CEST 对比。此外，该方法还可以清晰地区分糖胺聚糖测量值与软骨和滑液区域。这种均匀-MT CEST 方法在体内分子成像（如大脑、骨骼肌等）中有广泛的应用。
