Dataset Information

A two-center analysis of hyperpolarized 129Xe lung MRI in stable pediatric cystic fibrosis: Potential as a biomarker for multi-site trials.

ABSTRACT: BACKGROUND:The ventilation defect percent (VDP), measured from hyperpolarized (HP) 129Xe magnetic resonance imaging (MRI), is sensitive to functional changes in cystic fibrosis (CF) lung disease. The purpose of this study was to measure and compare VDP from HP 129Xe MRI acquired at two institutions in stable pediatric CF subjects with preserved lung function. METHODS:This retrospective analysis included 26 participants from two institutions (18 CF, 8 healthy, age range 10-17). Pulmonary function tests, N2 multiple breath washout (to measure lung clearance index, LCI), and HP 129Xe MRI were performed. VDP measurements were compared between two trained analysts using mean-anchored linear binning. Correlations were investigated for VDP compared to the forced expiratory volume in one second (FEV1) and LCI. RESULTS:VDP measurements agreed for the two analysts with an intraclass correlation coefficient of 0.99. In the combined dataset, VDP measured by Analyst 1 was 5.96?±?1.82% and 15.96?±?6.76% for the healthy and CF groups, respectively (p?=?.0004). Analyst 2 showed similar differences between healthy and CF (p?=?.0003). VDP measured by either analyst was shown to correlate with FEV1 (R2?=?0.33, p?=?.003; and R2?=?0.26, p?=?.009 for Analysts 1 and 2, respectively) and LCI (R2?=?0.76, p?

SUBMITTER: Couch MJ

PROVIDER: S-EPMC7054852 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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A two-center analysis of hyperpolarized <sup>129</sup>Xe lung MRI in stable pediatric cystic fibrosis: Potential as a biomarker for multi-site trials.

Couch Marcus J MJ Thomen Robert R Kanhere Nikhil N Hu Raymond R Ratjen Felix F Woods Jason J Santyr Giles G

Journal of cystic fibrosis : official journal of the European Cystic Fibrosis Society 20190325 5

<h4>Background</h4>The ventilation defect percent (VDP), measured from hyperpolarized (HP) <sup>129</sup>Xe magnetic resonance imaging (MRI), is sensitive to functional changes in cystic fibrosis (CF) lung disease. The purpose of this study was to measure and compare VDP from HP <sup>129</sup>Xe MRI acquired at two institutions in stable pediatric CF subjects with preserved lung function.<h4>Methods</h4>This retrospective analysis included 26 participants from two institutions (18 CF, 8 healthy, ...[more]

PMID: 30922812

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Project description:Computational fluid dynamics (CFD) simulations of respiratory airflow have the potential to change the clinical assessment of regional airway function in health and disease, in pulmonary medicine and otolaryngology. For example, in diseases where multiple sites of airway obstruction occur, such as obstructive sleep apnea (OSA), CFD simulations can identify which sites of obstruction contribute most to airway resistance and may therefore be candidate sites for airway surgery. The main barrier to clinical uptake of respiratory CFD to date has been the difficulty in validating CFD results against a clinical gold standard. Invasive instrumentation of the upper airway to measure respiratory airflow velocity or pressure can disrupt the airflow and alter the subject's natural breathing patterns. Therefore, in this study, we instead propose phase contrast (PC) velocimetry magnetic resonance imaging (MRI) of inhaled hyperpolarized 129Xe gas as a non-invasive reference to which airflow velocities calculated via CFD can be compared. To that end, we performed subject-specific CFD simulations in airway models derived from 1H MRI, and using respiratory flowrate measurements acquired synchronously with MRI. Airflow velocity vectors calculated by CFD simulations were then qualitatively and quantitatively compared to velocity maps derived from PC velocimetry MRI of inhaled hyperpolarized 129Xe gas. The results show both techniques produce similar spatial distributions of high velocity regions in the anterior-posterior and foot-head directions, indicating good qualitative agreement. Statistically significant correlations and low Bland-Altman bias between the local velocity values produced by the two techniques indicates quantitative agreement. This preliminary in vivo comparison of respiratory airway CFD and PC MRI of hyperpolarized 129Xe gas demonstrates the feasibility of PC MRI as a technique to validate respiratory CFD and forms the basis for further comprehensive validation studies. This study is therefore a first step in the pathway towards clinical adoption of respiratory CFD.

Project description:Magnetic-resonance spectroscopy and imaging using hyperpolarized xenon-129 show great potential for evaluation of the most important function of the human lung -- gas exchange. In particular, chemical shift saturation recovery (CSSR) xenon-129 spectroscopy provides important physiological information for the lung as a whole by characterizing the dynamic process of gas exchange, while dissolved-phase (DP) xenon-129 imaging captures the time-averaged regional distribution of gas uptake by lung tissue and blood. Herein, we present recent advances in assessing lung function using CSSR spectroscopy and DP imaging in a total of 45 subjects (23 healthy, 13 chronic obstructive pulmonary disease (COPD) and 9 asthma). From CSSR acquisitions, the COPD subjects showed red blood cell to tissue-plasma (RBC-to-TP) ratios below the average for the healthy subjects (p < 0.001), but significantly higher septal wall thicknesses as compared with the healthy subjects (p < 0.005); the RBC-to-TP ratios for the asthmatic subjects fell outside two standard deviations (either higher or lower) from the mean of the healthy subjects, although there was no statistically significant difference for the average ratio of the study group as a whole. Similarly, from the 3D DP imaging acquisitions, we found that all the ratios (TP to gas phase (GP), RBC to GP, RBC to TP) measured in the COPD subjects were lower than those from the healthy subjects (p < 0.05 for all ratios), while these ratios in the asthmatic subjects differed considerably between subjects. Despite having been performed at different lung inflation levels, the RBC-to-TP ratios measured by CSSR and 3D DP imaging were fairly consistent with each other, with a mean difference of 0.037 (ratios from 3D DP imaging larger). In ten subjects the RBC-to-GP ratios obtained from the 3D DP imaging acquisitions were also highly correlated with their diffusing capacity of the lung for carbon monoxide per unit alveolar volume ratios measured by pulmonary function testing (R = 0.91).

Dataset Information

A two-center analysis of hyperpolarized 129Xe lung MRI in stable pediatric cystic fibrosis: Potential as a biomarker for multi-site trials.

Publications

A two-center analysis of hyperpolarized <sup>129</sup>Xe lung MRI in stable pediatric cystic fibrosis: Potential as a biomarker for multi-site trials.

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