Abstract
PurposeTo evaluate the reproducibility of indices of lung microstructure and function derived from 129Xe chemical shift saturation recovery (CSSR) spectroscopy in healthy volunteers and patients with chronic obstructive pulmonary disease (COPD), and to study the sensitivity of CSSR‐derived parameters to pulse sequence design and lung inflation level.MethodsPreliminary data were collected from five volunteers on three occasions, using two implementations of the CSSR sequence. Separately, three volunteers each underwent CSSR at three different lung inflation levels. After analysis of these preliminary data, five COPD patients were scanned on three separate days, and nine age‐matched volunteers were scanned three times on one day, to assess reproducibility.ResultsCSSR‐derived alveolar septal thickness (ST) and surface‐area‐to‐volume (S/V) ratio values decreased with lung inflation level (P < 0.001; P = 0.057, respectively). Intra‐subject standard deviations of ST were lower than the previously measured differences between volunteers and subjects with interstitial lung disease. The mean coefficient of variation (CV) values of ST were 3.9 ± 1.9% and 6.0 ± 4.5% in volunteers and COPD patients, respectively, similar to CV values for whole‐lung carbon monoxide diffusing capacity. The mean CV of S/V in volunteers and patients was 14.1 ± 8.0% and 18.0 ± 19.3%, respectively.Conclusion 129Xe CSSR presents a reproducible method for estimation of alveolar septal thickness. Magn Reson Med 77:2107–2113, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Highlights
Over the past two decades, hyperpolarized gas MRI with 3He and 129Xe has become a well-established functional research tool for assessment of lung ventilation and microstructure [1,2,3]
For two chronic obstructive pulmonary disease (COPD) patients (64 (F) and 67 (F)), data were only successfully acquired once on the first day of scanning, and in a third patient (71 (M)), the spectral SNR was insufficient in one scan from the first day
Preliminary study (i): Mean septal thickness (ST) values in the five healthy volunteers derived from multi-sweep and multisat sequences were 11.5 6 0.9 mm and 12.6 6 1.2 mm, and the corresponding mean coefficient of variation (CV) values of ST were 4.1 6 1.3% and 10.0 6 7.4%, respectively
Summary
Over the past two decades, hyperpolarized gas MRI with 3He and 129Xe has become a well-established functional research tool for assessment of lung ventilation and microstructure [1,2,3]. A number of MR techniques have been developed to study pulmonary gas exchange with hyperpolarized 129Xe [4,5,6], exploiting the solubility of xenon in somatic substances and the large chemical shift difference of 129Xe in lung tissue and blood plasma (T/P) and red blood cells (RBCs) (corresponding to resonances at 197 and 218 ppm downfield from the 129Xe gas resonance, respectively). The reproducibility of MR-derived functional measures is critical to determining their sensitivity and robustness for future clinical applications as a quantitative outcome measure [12].
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