Dual-frequency irradiation chemical exchange saturation transfer (dualCEST) allows imaging of endogenous bulk mobile proteins by selectively measuring the intramolecular spin diffusion. The resulting specificity to changes in the concentration, molecular size, and folding state of mobile proteins is of particular interest as a marker for neurodegenerative diseases and cancer. Until now, application of dualCEST in clinical trials was prevented by the inherently small signal-to-noise ratio and the resulting comparatively long examination time. In this study, we present an optimized acquisition protocol allowing 3D dualCEST-MRI examinations in a clinically relevant time frame. The optimization comprised the extension of the image readout to 3D, allowing a retrospective co-registration and application of denoising strategies. In addition, cosine-modulated dual-frequency presaturation pulses were implemented with a weighted acquisition scheme of the necessary frequency offsets. The optimization resulted in a signal-to-noise ratio gain by a factor of approximately 8. In particular, the application of denoising and the motion correction were the most crucial improvement steps. In vitro experiments verified the preservation of specificity of the dualCEST signal to proteins. Good-to-excellent intra-session and good inter-session repeatability was achieved, allowing reliable detection of relative signal differences of about 16% or higher. Applicability in a clinical setting was demonstrated by examining a patient with glioblastoma. The optimized acquisition protocol for dualCEST-MRI at 3 T enables selective imaging of endogenous bulk mobile proteins under clinically relevant conditions.

中文翻译：

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优化的dualCEST-MRI可对人脑中的内源性大量移动​​蛋白进行成像。

双频辐射化学交换饱和转移（dualCEST）允许通过选择性地测量分子内自旋扩散来成像内源性大量移动​​蛋白。产生的对移动蛋白浓度，分子大小和折叠状态变化的特异性作为神经退行性疾病和癌症的标志物特别引起关注。迄今为止，由于固有的小信噪比和相对较长的检查时间，一直无法在临床试验中使用DualCEST。在这项研究中，我们提出了一种优化的采集方案，允许在临床相关的时间范围内进行3D dualCEST-MRI检查。优化包括将图像读取扩展到3D，从而可以进行回顾性共配准和去噪策略的应用。此外，余弦调制双频预饱和脉冲通过必要的频率偏移的加权采集方案实现。优化后，信噪比增益提高了约8倍。特别是，去噪和运动校正是最关键的改进步骤。体外实验证实了DualCEST信号对蛋白质的特异性得以保留。实现了会话期间的良好到优秀和会话之间的良好重复性，从而可以可靠地检测到大约16％或更高的相对信号差异。通过检查胶质母细胞瘤患者证明了其在临床环境中的适用性。针对DualCEST-MRI在3 T时的优化采集方案，可以在临床相关条件下对内源性大量移动​​蛋白进行选择性成像。