Relaxation-Compensated Chemical Exchange Saturation Transfer MRI in the Brain at 7T: Application in Relapsing-Remitting Multiple Sclerosis.
Relaxation-Compensated Chemical Exchange Saturation Transfer MRI in the Brain at 7T: Application in Relapsing-Remitting Multiple Sclerosis.
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DOI：
10.3389/fneur.2022.764690
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发表时间：
2022
影响因子：
3.4
通讯作者：
Smith SA
中科院分区：
文献类型：
--
作者：
O'Grady KP;Satish S;Owen QR;Box BA;Bagnato F;Combes AJE;Cook SR;Westervelt HJ;Feiler HR;Lawless RD;Sarma A;Malone SD;Ndolo JM;Yoon K;Dortch RD;Rogers BP;Smith SA
化学交换饱和转移（CEST）磁共振成像（MRI）可以在不需要外源性造影剂的情况下以高分辨率和灵敏度探测体内组织生物化学。在磁场中应用CEST MRI提供了增加光谱分辨率和提高对具有更快质子交换率的代谢物（如谷氨酸盐，大脑中的关键神经递质）的灵敏度的优势。先前的磁共振波谱和CEST MRI研究揭示了多发性硬化症（MS）患者谷氨酸调节的改变。虽然CEST成像有助于研究这种复杂和异质性神经疾病的病理学的新策略，但CEST信号被并发效应污染或稀释（例如，半固体磁化转移（MT）和直接水饱和度），并且通过自由水池的T1弛豫时间来缩放，自由水池的T1弛豫时间也可以在疾病的情况下改变。在这项研究中，20例复发缓解型MS患者和年龄和性别匹配的健康志愿者，在7.0 T下获得谷氨酸加权CEST数据。使用洛伦兹拟合程序从CEST z-光谱中去除不对称MT贡献，并使用从反转恢复序列导出的R1图应用表观交换依赖性弛豫（AREX）校正，以进一步将谷氨酸加权CEST信号与并发效应分离。使用MS组合中的认知功能最小评估来检查AREX与认知功能之间的关联。将CEST效应与MT、直接水饱和度和T1效应分离后，灰质中谷氨酸加权AREX对比度仍高于白色物质，尽管这些组织之间的差异减小。MS患者正常灰质和白色物质中的谷氨酸加权AREX与健康灰质和白色物质无差异，但在白色物质病变中显著升高。某些皮质区域和白色病变中的AREX与MS患者的残疾和认知功能测量相关。然而，由于潜在的混杂效应，需要更大样本量的进一步研究来证实这些关系。本研究中MT和AREX校正的应用证明了分离CEST信号对于更具体地表征MS中代谢变化对组织病理学和症状的贡献的重要性。
Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) can probe tissue biochemistry in vivo with high resolution and sensitivity without requiring exogenous contrast agents. Applying CEST MRI at ultrahigh field provides advantages of increasing spectral resolution and improving sensitivity to metabolites with faster proton exchange rates such as glutamate, a critical neurotransmitter in the brain. Prior magnetic resonance spectroscopy and CEST MRI studies have revealed altered regulation of glutamate in patients with multiple sclerosis (MS). While CEST imaging facilitates new strategies for investigating the pathology underlying this complex and heterogeneous neurological disease, CEST signals are contaminated or diluted by concurrent effects (e.g., semi-solid magnetization transfer (MT) and direct water saturation) and are scaled by the T1 relaxation time of the free water pool which may also be altered in the context of disease. In this study of 20 relapsing-remitting MS patients and age- and sex-matched healthy volunteers, glutamate-weighted CEST data were acquired at 7.0 T. A Lorentzian fitting procedure was used to remove the asymmetric MT contribution from CEST z-spectra, and the apparent exchange-dependent relaxation (AREX) correction was applied using an R1 map derived from an inversion recovery sequence to further isolate glutamate-weighted CEST signals from concurrent effects. Associations between AREX and cognitive function were examined using the Minimal Assessment of Cognitive Function in MS battery. After isolating CEST effects from MT, direct water saturation, and T1 effects, glutamate-weighted AREX contrast remained higher in gray matter than in white matter, though the difference between these tissues decreased. Glutamate-weighted AREX in normal-appearing gray and white matter in MS patients did not differ from healthy gray and white matter but was significantly elevated in white matter lesions. AREX in some cortical regions and in white matter lesions correlated with disability and measures of cognitive function in MS patients. However, further studies with larger sample sizes are needed to confirm these relationships due to potential confounding effects. The application of MT and AREX corrections in this study demonstrates the importance of isolating CEST signals for more specific characterization of the contribution of metabolic changes to tissue pathology and symptoms in MS.
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化学交换饱和转移在7 t的发展。
影响因子：
3.3
作者：
Dula, Adrienne N.;Asche, Elizabeth M.;Landman, Bennett A.;Welch, E. Brian;Pawate, Siddharama;Sriram, Subramaniam;Gore, John C.;Smith, Seth A.
通讯作者：
Smith, Seth A.
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Smith, Seth A.
影响因子：
3.9
作者：
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通讯作者：
Munschauer, F
影响因子：
4.4
作者：
Haedel, Sven;Wirth, Christoph;Schubert, Florian
通讯作者：
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影响因子：
5.7
作者：
Huo, Yuankai;Xu, Zhoubing;Landman, Bennett A.
通讯作者：
Landman, Bennett A.