Doan Bich-Thuy, Autret Gwennhael, Mispelter Joël, Méric Philippe, Même William, Montécot-Dubourg Céline, Corrèze Jean-Loup, Szeremeta Frédéric, Gillet Brigitte, Beloeil Jean-Claude
Laboratoire de RMN biologique, ICSN-CNRS, UPR, 2301, Avenue de la Terrasse, 91198 Gif sur Yvette cedex, France.
J Magn Reson. 2009 May;198(1):94-104. doi: 10.1016/j.jmr.2009.01.023. Epub 2009 Jan 25.
(13)C spectroscopy combined with the injection of (13)C-labeled substrates is a powerful method for the study of brain metabolism in vivo. Since highly localized measurements are required in a heterogeneous organ such as the brain, it is of interest to augment the sensitivity of (13)C spectroscopy by proton acquisition. Furthermore, as focal cerebral lesions are often encountered in animal models of disorders in which the two brain hemispheres are compared, we wished to develop a bi-voxel localized sequence for the simultaneous bilateral investigation of rat brain metabolism, with no need for external additional references. Two sequences were developed at 9.4T: a bi-voxel (1)H-((13)C) STEAM-POCE (Proton Observed Carbon Edited) sequence and a bi-voxel (1)H-((13)C) PRESS-POCE adiabatically decoupled sequence with Hadamard encoding. Hadamard encoding allows both voxels to be recorded simultaneously, with the same acquisition time as that required for a single voxel. The method was validated in a biological investigation into the neuronal damage and the effect on the Tri Carboxylic Acid cycle in localized excitotoxic lesions. Following an excitotoxic quinolinate-induced localized lesion in the rat cortex and the infusion of U-(13)C glucose, two (1)H-((13)C) spectra of distinct (4x4x4mm(3)) voxels, one centred on the injured hemisphere and the other on the contralateral hemisphere, were recorded simultaneously. Two (1)H bi-voxel spectra were also recorded and showed a significant decrease in N-acetyl aspartate, and an accumulation of lactate in the ipsilateral hemisphere. The (1)H-((13)C) spectra could be recorded dynamically as a function of time, and showed a fall in the glutamate/glutamine ratio and the presence of a stable glutamine pool, with a permanent increase of lactate in the ipsilateral hemisphere. This bi-voxel (1)H-((13)C) method can be used to investigate simultaneously both brain hemispheres, and to perform dynamic studies. We report here the neuronal damage and the effect on the Tri Carboxylic Acid cycle in localized excitotoxic lesions.
碳-13（¹³C）光谱与¹³C标记底物注射相结合是一种用于体内脑代谢研究的强大方法。由于在诸如大脑这样的异质器官中需要进行高度局部化的测量，因此通过质子采集来提高¹³C光谱的灵敏度是很有意义的。此外，由于在比较两个脑半球的疾病动物模型中经常会遇到局灶性脑损伤，我们希望开发一种双体素定位序列，用于同时对大鼠脑代谢进行双侧研究，而无需外部额外参考。在9.4T场强下开发了两种序列：一种双体素质子观测碳编辑（¹H-¹³C）STEAM-POCE序列和一种采用哈达玛编码的双体素质子观测碳编辑绝热去耦（¹H-¹³C）PRESS-POCE序列。哈达玛编码允许同时记录两个体素，其采集时间与单个体素所需的时间相同。该方法在一项关于局部兴奋性毒性损伤中神经元损伤及对三羧酸循环影响的生物学研究中得到了验证。在大鼠皮层中由兴奋性毒性喹啉酸诱导产生局部损伤并注入U-¹³C葡萄糖后，同时记录了两个不同的（4×4×4mm³）体素的¹H-¹³C光谱，一个位于受损半球中心，另一个位于对侧半球中心。还记录了两个¹H双体素光谱，显示同侧半球中N-乙酰天门冬氨酸显著减少以及乳酸积累。¹H-¹³C光谱可以作为时间的函数进行动态记录，显示谷氨酸/谷氨酰胺比值下降以及存在稳定的谷氨酰胺池，同侧半球中乳酸持续增加。这种双体素¹H-¹³C方法可用于同时研究两个脑半球，并进行动态研究。我们在此报告局部兴奋性毒性损伤中的神经元损伤及对三羧酸循环的影响。
