使用定量MRI表征气道黏液：一项体外概念验证研究

文献信息

中文摘要

目的： 慢性阻塞性肺疾病的一个特征是黏液高分泌。在这项概念验证研究中，我们旨在使用定量超短回波时间（UTE）磁共振成像（MRI）序列，在受控的体外合成黏液模型中表征气道黏液，为未来体内研究建立技术基础。
材料与方法： 采用UTE双回波稳态（UTE-DESS）采集类自由感应衰减信号和类自旋/受激回波信号回波；估算定量MRI参数（T1、T2和扩散率）。使用黏蛋白（0.20%、0.50%和1.0%）与黄原胶（0.10%、0.25%和0.50%）混合制备合成黏液体模，以复制人喉部黏液的黏弹性，并将样品包埋于1%琼脂中进行成像。
结果： 不同黏蛋白和黄原胶浓度的黏液体模在颜色和不透明度上表现出视觉差异。相对黏液浓度为1、2.5和5的三支试管，估算T1值分别为2.23 ± 0.16、2.37 ± 0.20和2.09 ± 0.18 s（均值 ± 标准差）。相应T2值分别为806.6 ± 105.6、687.4 ± 78.0和475.0 ± 41.3 ms，而三支试管的扩散率值分别为2.36 ± 0.14、2.31 ± 0.18和2.33 ± 0.18 µm2/ms。仅T2弛豫时间与黏液浓度呈显著线性相关（r = -0.9998，p = 0.0112）。
结论： UTE-DESS MRI用于表征气道黏液可能是可行的。T2弛豫时间与黏液浓度增加呈强负相关，表明其对黏液含量具有敏感性。
要点： 问题：一种新型定量超短回波时间MRI序列能否无创地表征气道黏液特性，并克服黏液阻塞性疾病中传统肺部成像的局限性？发现：在该受控体外模型中，UTE-DESS MRI映射显示，仅T2弛豫时间与黏液浓度增加呈强负相关。相关性声明：这一探索性概念验证为未来体内研究中无辐射、无创的T2映射监测和表型分析慢性阻塞性肺疾病及其他黏液阻塞性肺疾病建立了技术基础。

英文摘要

OBJECTIVES: A characteristic of chronic obstructive pulmonary disease is mucus hypersecretion. In this proof-of-concept study, we aimed to characterize airway mucus using a quantitative ultrashort echo time (UTE) magnetic resonance imaging (MRI) sequence in a controlled in vitro synthetic mucus model to establish a technical foundation for future in vivo studies.
MATERIALS AND METHODS: UTE double-echo steady-state (UTE-DESS) was performed to acquire the signal from free induction decay-like signal and spin/stimulated echo-like signal echoes; quantitative MRI parameters (T1, T2, and diffusivity) were estimated. Synthetic mucus phantoms were prepared using mucin (0.20%, 0.50%, and 1.0%) mixed with xanthan gum (0.10%, 0.25%, and 0.50%) to replicate the viscoelastic properties of human laryngeal mucus, and samples were embedded in 1% agar for imaging.
RESULTS: The mucus phantoms with varying concentrations of mucin and xanthan exhibited visual differences in color and opacity. Estimated T1 values were 2.23 ± 0.16, 2.37 ± 0.20, and 2.09 ± 0.18 s (mean ± standard deviation) for the three tubes with relative mucus concentrations of 1, 2.5, and 5, respectively. Corresponding T2 values were 806.6 ± 105.6, 687.4 ± 78.0, and 475.0 ± 41.3 ms, while diffusivity values were 2.36 ± 0.14, 2.31 ± 0.18, and 2.33 ± 0.18 µm2/ms for the three tubes. Only the T2 relaxation times showed a significant linear correlation with mucus concentration (r = -0.9998, p = 0.0112).
CONCLUSION: UTE-DESS MRI could be feasible for characterizing airway mucus. T2 relaxation time showed a strong inverse correlation with increasing mucus concentration, indicating its sensitivity to mucus content.
KEY POINTS: Question Can a novel quantitative ultrashort echo time MRI sequence noninvasively characterize airway mucus properties and overcome conventional lung imaging limitations in muco-obstructive diseases? Findings In this controlled in vitro model, UTE-DESS MRI mapping demonstrated that T2 relaxation times alone showed a strong inverse correlation with increasing mucus concentrations. Relevance statement This exploratory proof-of-concept establishes a technical foundation for radiation-free, noninvasive T2 mapping to monitor and phenotype chronic obstructive pulmonary disease and other mucoobstructive lung diseases in future in vivo studies.