Feasibility of transient nuclear Overhauser effect imaging in brain at 7 T.
Feasibility of transient nuclear Overhauser effect imaging in brain at 7 T.
复制标题
7 T 脑内瞬态核欧沃豪塞效应成像的可行性。
DOI：
10.1002/mrm.29519
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发表时间：
2023
影响因子：
3.3
通讯作者：
Reddy,Ravinder
中科院分区：
文献类型：
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作者：
Kumar,Dushyant;Benyard,Blake;Soni,NarayanDatt;Swain,Anshuman;Wilson,Neil;Reddy,Ravinder
目的稳态NOE成像的NOE定量受到多种非NOE特异性干扰源的影响，包括直接饱和、磁化转移和相关化学交换物种，并受到B 0和B1+不均匀性的影响。去卷积这些混杂效应所需的B 0依赖性和B1+依赖性数据将大幅增加扫描时间，导致其他问题，如患者耐受性。在这里，我们证明了脑脂质映射的可行性，使用一个容易实现的瞬态NOE（tNOE）approach.MethodsThis 7 T研究使用频率选择性反转脉冲的频率偏移范围为1.0和5.0百万分之一（ppm）和−5.0和−1.0 ppm相对于散装水峰。随后是固定/可变混合时间，然后是单次2D turbo FLASH读数。tNOE测量的可行性，证明牛血清白蛋白phanasteroid和健康的人脑。ResultsThe tNOE测量从牛血清白蛋白phanasteroid被发现是独立的生理pH值的变化。牛血清白蛋白体和人脑均显示出广泛的tNOE贡献，相对于水峰，tNOE贡献集中在约-3.5 ppm处，推测脂质和蛋白质中的脂肪族部分是主要贡献者。还检测到相对于水约+2.5 ppm的不太显著的tNOE贡献，推测来自芳香族部分。这些芳香信号不含任何CEST信号。结论在本研究中，我们证明了在7 T下在人脑中进行tNOE的可行性。该方法比稳态NOE更节省扫描时间，并提供具有最小混杂因素的NOE测量。
PurposeThe nuclear Overhauser effect (NOE) quantification from the steady‐state NOE imaging suffers from multiple confounding non‐NOE‐specific sources, including direct saturation, magnetization transfer, and relevant chemical exchange species, and is affected by B0and B1+inhomogeneities. The B0‐dependent and B1+‐dependent data needed for deconvolving these confounding effects would increase the scan time substantially, leading to other issues such as patient tolerability. Here, we demonstrate the feasibility of brain lipid mapping using an easily implementable transient NOE (tNOE) approach.MethodsThis 7T study used a frequency‐selective inversion pulse at a range of frequency offsets between 1.0 and 5.0 parts per million (ppm) and −5.0 and −1.0 ppm relative to bulk water peak. This was followed by a fixed/variable mixing time and then a single‐shot 2D turbo FLASH readout. The feasibility of tNOE measurements is demonstrated on bovine serum albumin phantoms and healthy human brains.ResultsThe tNOE measurements from bovine serum albumin phantoms were found to be independent of physiological pH variations. Both bovine serum albumin phantoms and human brains showed broad tNOE contributions centered at approximately −3.5 ppm relative to water peak, with presumably aliphatic moieties in lipids and proteins being the dominant contributors. Less prominent tNOE contributions of approximately +2.5 ppm relative to water, presumably from aromatic moieties, were also detected. These aromatic signals were free from any CEST signals.ConclusionIn this study, we have demonstrated the feasibility of tNOE in human brain at 7 T. This method is more scan‐time efficient than steady‐state NOE and provides NOE measurement with minimal confounders.