Huang Zhiwei, Emir Uzay, Döring André, Klauser Antoine, Xiao Ying, Widmaier Mark, Xin Lijing
CIBM Center for Biomedical Imaging, Lausanne, Switzerland.
Animal Imaging and Technology, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
Hum Brain Mapp. 2025 Mar;46(4):e70176. doi: 10.1002/hbm.70176.
Whole-brain proton magnetic resonance spectroscopic imaging (H-MRSI) is a non-invasive technique for assessing neurochemical distribution in the brain, offering valuable insights into brain functions and neural diseases. It greatly benefits from the improved SNR at ultrahigh field strengths (≥ 7T). However, H-MRSI still faces several challenges, such as long acquisition time and severe signal contamination from water and lipids. In this study, 2D and 3D short TR/TE H-FID-MRSI sequences using rosette trajectories were developed with nominal spatial resolutions of 4.48 × 4.48 mm and 4.48 × 4.48 × 4.50 mm, respectively. Water signals were suppressed using an optimized Five-variable-Angle-gaussian-pulses-with-ShorT-total-duration (FAST) water suppression scheme of 76 ms, and lipid signals were removed using the L regularization method. Metabolic maps of major H metabolites were obtained in 5:40 min with 16 averages and 1 average for the 2D and 3D acquisitions, respectively. Excellent intra-session reproducibility was shown, with the coefficients of variance (CV) being lower than 6% for N-Acetyl-L-aspartic acid (NAA), Glutamate (Glu), total Choline (tCho), Creatine and Phosphocreatine (tCr), and Glycine and Myo-inositol (Gly + Ins). To explore the potential of further acceleration, compressed sensing was applied retrospectively to the 3D datasets. The structural similarity index (SSIM) remained above 0.85 and 0.8 until R = 2 and 3 for the metabolite maps of Glu, NAA, tCr, and tCho, indicating the possibility for further reduction of acquisition time to around 2 min.
全脑质子磁共振波谱成像（H-MRSI）是一种用于评估脑内神经化学物质分布的非侵入性技术，能为脑功能和神经疾病提供有价值的见解。它在超高场强（≥7T）下，因信噪比提高而受益匪浅。然而，H-MRSI仍面临一些挑战，如采集时间长以及来自水和脂质的严重信号污染。在本研究中，开发了使用玫瑰花结轨迹的二维和三维短TR/TE H-FID-MRSI序列，其标称空间分辨率分别为4.48×4.48毫米和4.48×4.48×4.50毫米。使用76毫秒的优化五变量角高斯短总时长脉冲（FAST）水抑制方案抑制水信号，并使用L正则化方法去除脂质信号。二维和三维采集分别在5分40秒内进行16次平均和1次平均，获得了主要H代谢物的代谢图谱。结果显示出了出色的组内重现性，N-乙酰-L-天冬氨酸（NAA）、谷氨酸（Glu）、总胆碱（tCho）、肌酸和磷酸肌酸（tCr）以及甘氨酸和肌醇（Gly+Ins）的变异系数（CV）低于6%。为了探索进一步加速的潜力，对三维数据集进行了回顾性压缩感知应用。对于Glu、NAA、tCr和tCho的代谢物图谱，直到加速因子R分别为2和3时，结构相似性指数（SSIM）仍保持在0.85和0.8以上，这表明采集时间有可能进一步缩短至约2分钟。
