Bader Viola, Strasser Bernhard, Bogner Wolfgang, Hingerl Lukas, Frese Sabina, Duguid Anna, Osburg Aaron, Clarke William T, Motyka Stanislav, Krssak Martin, Trattnig Siegfried, Scherer Thomas, Lanzenberger Rupert, Niess Fabian
High Field MR Center, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria.
Christian Doppler Laboratory for MR Imaging Biomarkers (BIOMAK), Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria.
NMR Biomed. 2025 Feb;38(2):e5311. doi: 10.1002/nbm.5311.
Deuterium metabolic imaging (DMI) is an emerging Magnetic Resonance technique providing valuable insight into the dynamics of cellular glucose (Glc) metabolism of the human brain in vivo using deuterium-labeled (H) glucose as non-invasive tracer. Reliable concentration estimation of H-Glc and downstream synthesized neurotransmitters glutamate + glutamine (Glx) requires accurate knowledge of relaxation times, but so far tissue-specific T and T relaxation times (e.g., in gray and white matter) have not been determined. Such measurements are time-consuming and particularly challenging in the presence of dynamically changing metabolite levels (e.g. H Glc and H Glx). This study aimed to assess T and T relaxation times of deuterated resonances, i.e., water, Glc and Glx in human gray and white matter using inversion recovery and Hahn spin-echo H MRSI (magnetic resonance spectroscopic imaging), respectively, with non-Cartesian concentric ring trajectory readout (CRT) including specific k-space reordering at 7 T. The sequence was validated using phantom measurements and all results were compared to unlocalized acquisitions. Thirteen healthy volunteers participated in the study, with 10 of them scanned ~90 min after oral administration of 0.8 g/kg [6,6'-H]-glucose. Significantly different T and T relaxation was observed between GM and WM for H water (T = 358 ± 21/328 ± 12/335 m ± 6 ms, p = 0.01) and H Glx (T = 37 ± 2/35 ± 2/33 ± 3 ms, p = 0.02), respectively, consistent with unlocalized acquisitions. No significant regional differences were found for H water (T = 36 ± 2/34 ± 2/31 ± 2 ms, p = 0.08), H Glc (T = 70 ± 5/73 ± 4/80 ± 5 ms, p = 0.13; T = 36 ± 1/34 ± 2/34 ± 2 ms, p = 0.24) and Glx (T = 172 ± 15/172 ± 12/165 ± 11 ms, p = 1.00). Knowledge of tissue-specific relaxation times can enhance the accuracy of concentration estimation and metabolic flux rates in future studies, potentially improving our understanding of various brain diseases such as cancer, neurodegenerative diseases or diabetes, which are often linked to impaired glucose metabolism.
氘代谢成像（DMI）是一种新兴的磁共振技术，它使用氘标记（H）葡萄糖作为非侵入性示踪剂，能够在体内对人类大脑细胞葡萄糖（Glc）代谢动力学提供有价值的见解。可靠地估计H-Glc和下游合成神经递质谷氨酸+谷氨酰胺（Glx）的浓度需要准确了解弛豫时间，但到目前为止，尚未确定组织特异性的T1和T2弛豫时间（例如在灰质和白质中）。这种测量既耗时，在代谢物水平动态变化（例如H Glc和H Glx）的情况下尤其具有挑战性。本研究旨在分别使用反转恢复和哈恩自旋回波H MRSI（磁共振波谱成像），通过非笛卡尔同心环轨迹读出（CRT），包括在7 T时特定的k空间重新排序，来评估人体灰质和白质中氘化共振（即水、Glc和Glx）的T1和T2弛豫时间。该序列通过模体测量进行了验证，所有结果都与非定位采集进行了比较。13名健康志愿者参与了该研究，其中10人在口服0.8 g/kg [6,6'-H]-葡萄糖后约90分钟进行了扫描。对于H水（T1 = 358 ± 21/328 ± 12/335 ± 6 ms，p = 0.01）和H Glx（T2 = 37 ± 2/35 ± 2/33 ± 3 ms，p = 0.02），在GM和WM之间分别观察到了显著不同的T1和T2弛豫，这与非定位采集结果一致。对于H水（T1 = 36 ±
