Else Kröner Fresenius Center for Nutritional Medicine, ZIEL-Institute for Food and Health, Technical University of Munich, Freising, Germany.
Department of Surgery, Klinikum rechts der Isar, School of Medicine and Health, Technical University of Munich, Munich, Germany.
NMR Biomed. 2024 Oct;37(10):e5181. doi: 10.1002/nbm.5181. Epub 2024 Jun 3.
The aim of this work is to develop an ω-3 fatty acid fraction mapping method at 3 T based on a chemical shift encoding model, to assess its performance in a phantom and in vitro study, and to further demonstrate its feasibility in vivo.
A signal model was heuristically derived based on spectral appearance and theoretical considerations of the corresponding molecular structures to differentiate between ω-3 and non-ω-3 fatty acid substituents in triacylglycerols in addition to the number of double bonds (ndb), the number of methylene-interrupted double bonds (nmidb), and the mean fatty acid chain length (CL). First, the signal model was validated using single-voxel spectroscopy and a time-interleaved multi-echo gradient-echo (TIMGRE) sequence in gas chromatography-mass spectrometry (GC-MS)-calibrated oil phantoms. Second, the TIMGRE-based method was validated in vitro in 21 adipose tissue samples with corresponding GC-MS measurements. Third, an in vivo feasibility study was performed for the TIMGRE-based method in the gluteal region of two healthy volunteers. Phantom and in vitro data was analyzed using a Bland-Altman analysis.
Compared with GC-MS, MRS showed in the phantom study significant correlations in estimating the ω-3 fraction (p < 0.001), ndb (p < 0.001), nmidb (p < 0.001), and CL (p = 0.001); MRI showed in the phantom study significant correlations (all p < 0.001) for the ω-3 fraction, ndb, and nmidb, but no correlation for CL. Also in the in vitro study, significant correlations (all p < 0.001) between MRI and GC-MS were observed for the ω-3 fraction, ndb, and nmidb, but not for CL. An exemplary ROI measurement in vivo in the gluteal subcutaneous adipose tissue yielded (mean ± standard deviation) 0.8% ± 1.9% ω-3 fraction.
The present study demonstrated strong correlations between gradient-echo imaging-based ω-3 fatty acid fraction mapping and GC-MS in the phantom and in vitro study. Furthermore, feasibility was demonstrated for characterizing adipose tissue in vivo.
本研究旨在基于化学位移编码模型开发一种在 3T 下的ω-3 脂肪酸分数测绘方法，评估其在体模和体外研究中的性能，并进一步证明其在体内的可行性。
基于光谱外观和相应分子结构的理论考虑，启发式地推导出一个信号模型，以区分甘油三酯中的 ω-3 和非 ω-3 脂肪酸取代物，以及双键数（ndb）、甲基中断双键数（nmidb）和脂肪酸链长平均值（CL）。首先，使用单体素波谱和时间交错多回波梯度回波（TIMGRE）序列在气相色谱-质谱（GC-MS）校准油体模中验证信号模型。其次，在 21 个脂肪组织样本中使用基于 TIMGRE 的方法进行体外验证，并与 GC-MS 测量结果相对比。最后，在两名健康志愿者的臀区进行基于 TIMGRE 的方法的体内可行性研究。使用 Bland-Altman 分析对体模和体外数据进行分析。
与 GC-MS 相比，MRS 在体模研究中显示出对 ω-3 分数（p<0.001）、ndb（p<0.001）、nmidb（p<0.001）和 CL（p=0.001）的显著相关性；MRI 在体模研究中显示出对 ω-3 分数、ndb 和 nmidb 的显著相关性（均 p<0.001），但对 CL 没有相关性。在体外研究中，MRI 与 GC-MS 之间也观察到显著相关性（均 p<0.001），但对 CL 无相关性。在臀区皮下脂肪组织的体内 ROI 测量中，（平均值±标准差）获得 0.8%±1.9%的 ω-3 分数。
本研究在体模和体外研究中证明了基于梯度回波成像的 ω-3 脂肪酸分数测绘与 GC-MS 之间具有很强的相关性。此外，还证明了其在体内描绘脂肪组织的可行性。
