超极化氙溶解相 MRI 区域性肺功能指标的可重复性。
Repeatability of regional pulmonary functional metrics of Hyperpolarized Xe dissolved-phase MRI.
机构信息
Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA.
Department of Biostatistics and Medical Informatics, University of Wisconsin, Madison, Wisconsin, USA.
出版信息
J Magn Reson Imaging. 2019 Oct;50(4):1182-1190. doi: 10.1002/jmri.26745. Epub 2019 Apr 10.
BACKGROUND
MRI of hyperpolarized Xenon (HP Xe) is increasingly utilized for investigating pulmonary function. The solubility of HP Xe in lung tissue, blood plasma (Barrier), and red blood cells (RBC), with unique chemical shifts, enables spectroscopic imaging of potential imaging biomarkers of gas exchange and microstructural pulmonary physiology.
PURPOSE
To quantify global average and regional repeatability of Barrier:gas, RBC:gas, and RBC:Barrier ratios derived from dissolved-phase Xe imaging and their dependence on intervisit changes in lung inflation volume.
STUDY TYPE
Prospective.
POPULATION
Fourteen healthy volunteers. One subject was unable to complete the study resulting in 13 subjects for analysis (eight female, five male, ages 24-69, 53.8 ± 13.9).
FIELD STRENGTH
1.5T.
ASSESSMENT
Subjects were imaged using a 3D radial 1-point Dixon method to separate Barrier and RBC component signals, at two different timepoints, with ~1 month between visits. RBC:Gas, Barrier:Gas, and RBC:Barrier measures were compared across time and with pulmonary function tests (PFTs).
STATISTICAL TESTS
Repeatablilty was quantified using Bland-Altman plots, coefficient of repeatability, coefficient of variation (CV), and intraclass correlation coefficients (ICCs). Dependence of imaging measures on PFTs and lung volume was evaluated using Spearman and Pearson correlation coefficients, respectively. Statistical significance was determined by F-test for intraclass correlations, and t-test for Spearman correlations and regression.
RESULTS
Mean RBC:Gas, Barrier:Gas, and RBC:Barrier had CVs of 19.2%, 20.0%, and 11.5%, respectively, and had significant ICCs, equal to 0.78, 0.79, and 0.92, respectively. Intervisit differences in RBC:Barrier were significantly correlated with intervisit differences in DL (r = 0.93, P = 0.007). Significant correlations with intervisit lung volume differences and intervisit differences in mean RBC:Gas (r = -0.73, P = 0.005) and Barrier:Gas (r = -0.69, P = 0.009) were found.
DATA CONCLUSION
Three commonly used Xe MRI-based measures of gas-exchange show good repeatability, particularly the Barrier:RBC ratio, which did not depend on lung inflation volume and was strongly associated with intervisit changes in DL .
LEVEL OF EVIDENCE
1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;50:1182-1190.
背景
磁共振成像（MRI）的超极化氙气（HP Xe）越来越被用于研究肺功能。 HP Xe 在肺组织、血浆（屏障）和红细胞（RBC）中的溶解度，具有独特的化学位移，使气体交换和微观肺生理的潜在成像生物标志物的光谱成像成为可能。
目的
量化来自溶解相 Xe 成像的屏障：气体、RBC：气体和 RBC：屏障比的全局平均值和区域重复性，及其对肺膨胀体积的随时间变化的依赖性。
研究类型
前瞻性。
人群
14 名健康志愿者。一名受试者无法完成研究，因此有 13 名受试者（8 名女性，5 名男性，年龄 24-69 岁，53.8±13.9 岁）进行分析。
磁场强度
1.5T。
评估
使用 3D 径向 1 点 Dixon 方法对屏障和 RBC 成分信号进行成像，在两次不同的时间点，两次访问之间间隔约 1 个月。比较了 RBC：气体、屏障：气体和 RBC：屏障测量值在不同时间点与肺功能测试（PFT）之间的差异。
统计检验
使用 Bland-Altman 图、重复性系数、变异系数（CV）和组内相关系数（ICC）来量化重复性。使用 Spearman 和 Pearson 相关系数分别评估成像测量值对 PFT 和肺容积的依赖性。通过 F 检验评估组内相关性的统计学意义，通过 t 检验评估 Spearman 相关性和回归。
结果
RBC：气体、屏障：气体和 RBC：屏障的平均 CV 分别为 19.2%、20.0%和 11.5%，ICC 分别为 0.78、0.79 和 0.92，均具有显著的 ICC。RBC：屏障的随访差异与随访差异 DL（r = 0.93，P = 0.007）显著相关。还发现与随访时肺容积差异和随访时 RBC：气体（r = -0.73，P = 0.005）和屏障：气体（r = -0.69，P = 0.009）的平均差异显著相关。
数据结论
三种常用的基于 Xe MRI 的气体交换测量方法具有良好的重复性，特别是屏障：RBC 比值，它不依赖于肺膨胀体积，与 DL 的随时间变化密切相关。
证据水平
1 技术功效：第 1 阶段 J. Magn. Reson. Imaging 2019;50:1182-1190。
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