Noble gas pulmonary magnetic resonance imaging (MRI) is transitioning away from3He to129Xe gas, but the physiological/clinical relevance of129Xe apparent diffusion coefficient (ADC) parenchyma measurements is not well understood. Therefore, our objective was to generate129Xe MRI ADC for comparison with3He ADC and with well-established measurements of alveolar structure and function in older never-smokers and ex-smokers with chronic obstructive pulmonary disease (COPD). In four never-smokers and 10 COPD ex-smokers,3He (b = 1.6 sec/cm2) and129Xe (b = 12, 20, and 30 sec/ cm2) ADC, computed tomography (CT) density-threshold measurements, and the diffusing capacity for carbon monoxide (DLCO) were measured. To understand regional differences, the anterior-posterior (APG) and superior-inferior (ΔSI) ADC differences were evaluated. Compared to never-smokers, COPD ex-smokers showed greater3He ADC (P = 0.006),129Xe ADCb12 (P = 0.006), and ADCb20 (P = 0.006), but not for ADCb30 (P > 0.05). Never-smokers and COPD ex-smokers had significantly different APG for3He ADC (P = 0.02),129Xe ADCb12 (P = 0.006), and ADCb20 (P = 0.01), but not for ADCb30 (P > 0.05). ΔSI for never-and ex-smokers was significantly different for3He ADC (P = 0.046), but not for129Xe ADC (P > 0.05). There were strong correlations for DLCO with3He ADC and129Xe ADCb12 (both r = −0.95, P < 0.05); in a multivariate model129Xe ADCb12 was the only significant predictor of DLCO (P = 0.049). For COPD ex-smokers, CT relative area <_950 HU (RA950) correlated with3He ADC (r = 0.90, P = 0.008) and129Xe ADCb12 (r = 0.85, P = 0.03). In conclusion, while129Xe ADCb30 may be appropriate for evaluating subclinical or mild emphysema, in this small group of never-smokers and ex-smokers with moderate-to-severe emphysema,129Xe ADCb12 provided a physiologically appropriate estimate of gas exchange abnormalities and alveolar microstructure.
- Apparent diffusion coefficient
- HyperpolarizedHe MRI
- HyperpolarizedXe MRI
ASJC Scopus subject areas
- Physiology (medical)