GE Global Research Center, Niskayuna, New York 12309, USA.
J Magn Reson Imaging. 2009 Nov;30(5):1155-62. doi: 10.1002/jmri.21936.
To identify the pulse sequence and acquisition parameters that result in the most accurate and repeatable measurements of glutamate (Glu) concentration in the brain at 3T.
Simulations were performed to compare the accuracy and repeatability of 11 pulse sequences and acquisition parameters, within four general classes (PRESS, STEAM, Carr-Purcell PRESS [CPRESS] and TE averaged PRESS [JPRESS]), the majority of which were previously suggested as optimal for Glu detection. Three of the simulated acquisitions were implemented in a clinical scanner and measures of repeatability in vivo were compared to their simulated values.
Good agreement was demonstrated between simulated and experimentally determined measures of repeatability. Among the acquisitions considered, a CPRESS sequence with minimal echo time, together with, possibly, a short TE PRESS sequence, result in the most repeatable within session Glu measurements, while slightly overestimating the Glu concentration. Excellent accuracy is demonstrated by the simulations for a JPRESS sequence, at the expense of lower repeatability than optimal PRESS or CPRESS sequences.
Further proof of concept is presented toward validation of a simulation approach to understand pulse sequence performance in measuring the concentration of a given metabolite. Improved within session Glu measurement repeatability is predicted for CPRESS and demonstrated in vivo.
确定在 3T 下能最准确、可重复地测量脑内谷氨酸（Glu）浓度的脉冲序列和采集参数。
通过模拟，比较了 11 种脉冲序列和采集参数在 4 个一般类别（PRESS、STEAM、Carr-Purcell PRESS [CPRESS]和 TE 平均 PRESS [JPRESS]）内的准确性和可重复性，其中大多数之前被认为是检测 Glu 的最佳方法。其中 3 种模拟采集在临床扫描仪中实现，并将体内的可重复性测量与其模拟值进行了比较。
模拟和实验确定的可重复性测量之间表现出良好的一致性。在所考虑的采集方法中，最小回波时间的 CRESS 序列，以及可能的短 TE PRESS 序列，可实现最可重复的 Glu 测量，同时略微高估 Glu 浓度。模拟表明 JPRESS 序列具有出色的准确性，但与最佳 PRESS 或 CRESS 序列相比，其可重复性较低。
进一步验证了一种模拟方法来理解测量特定代谢物浓度的脉冲序列性能，这为验证概念提供了进一步的证据。预测 CRESS 可提高 Glu 测量的可重复性，并在体内得到证实。
