为评价5.0 T超高场磁共振下脂肪酸成分（fatty acid composition, FAC）定量的准确性，本研究通过系统评估成像维度、读出极性及回波时间组合等关键参数对化学位移编码FAC定量结果的影响，建立适用于人体脂肪组织的成像方案。采用多回波梯度回波序列采集油模与在体数据，基于脂肪多峰先验约束模型稳定拟合不饱和双键数（ndb）、亚甲基中断双键数（nmidb），以磁共振波谱作为参照验证准确性。结果显示，三维成像定量结果更接近NMR参考值；单、双极性读出FAC数值无明显差异；TE1<1.9 ms、ΔTE=0.6~1.0 ms的回波组合可显著提升拟合精度。人体腹部皮下脂肪测得ndb=2.817±0.067、nmidb=0.858±0.087，具有良好的一致性与稳定性。研究结果为5.0 T超高场磁共振FAC精准定量及其代谢疾病应用提供了技术基础。

This study evaluated the accuracy of fatty acid composition (FAC) quantification at 5.0 T ultra-high-field MRI by systematically assessing the effects of imaging dimensionality, readout polarity, and echo-time combination, and establishing a protocol for human adipose tissue. Multi-echo gradient-echo imaging was performed in oil phantoms and in vivo. The number of double bonds (ndb) and methylene-interrupted double bonds (nmidb) were stably estimated using a multi-peak fat prior-constrained model, with magnetic resonance spectroscopy as reference. Three-dimensional imaging yielded estimates closer to NMR values, while monopolar and bipolar readouts showed no significant differences. An echo-time combination of TE1<1.9 ms and ΔTE=0.6~1.0 ms significantly improved fitting accuracy. In human abdominal subcutaneous adipose tissue, ndb and nmidb were 2.817±0.067 and 0.858±0.087, respectively, demonstrating good consistency and stability. These results provide a technical basis for accurate FAC quantification at 5.0 T MRI and its application in metabolic disease research.