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Noble gas pulmonary magnetic resonance imaging ( MRI) is transitioning away from 3He to 129Xe gas, but the physiological/clinical relevance of 129Xe apparent diffusion coefficient ( ADC) parenchyma measurements is not well understood. Therefore, our objective was to generate 129Xe MRI ADC for comparison with 3He 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) and 129Xe ( 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 (∆ SI) ADC differences were evaluated. Compared to never-smokers, COPD ex-smokers showed greater 3He 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 for 3He ADC ( P = 0.02), 129Xe ADCb12 ( P = 0.006), and ADCb20 ( P = 0.01), but not for ADCb30 ( P > 0.05). ∆ SI for never- and ex-smokers was significantly different for 3He ADC ( P = 0.046), but not for 129Xe ADC ( P > 0.05). There were strong correlations for DLCO with 3He ADC and 129Xe ADCb12 (both r = −0.95, P < 0.05); in a multivariate model 129Xe ADCb12 was the only significant predictor of DLCO ( P = 0.049). For COPD ex-smokers, CT relative area <−950 HU ( RA950) correlated with 3He ADC ( r = 0.90, P = 0.008) and 129Xe ADCb12 ( r = 0.85, P = 0.03). In conclusion, while 129Xe 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. [ABSTRACT FROM AUTHOR]

Background: The functional effects of abnormal diffusing capacity for carbon monoxide (DLCO) in ex-smokers without chronic obstructive pulmonary disease (COPD) are not well understood. Objective: We aimed to evaluate and compare well established clinical, physiological and emerging imaging measurements in ex-smokers with normal spirometry and abnormal DLCO with a group of ex-smokers with normal spirometry and DLCO and ex-smokers with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I COPD. Methods We enrolled 38 ex-smokers and 15 subjects with stage I COPD who underwent spirometry, plethysmography, St George's Respiratory Questionnaire (SGRQ), 6 min Walk Test (6MWT), x-ray CT and hyperpolarised helium-3 (³He) MRI. The 6MWT distance (6MWD), SGRQ scores, ³He MRI apparent diffusion coefficients (ADC) and CT attenuation values below -950 HU (RA950) were evaluated. Results: Of 38 ex-smokers without COPD, 19 subjects had abnormal DLCO with significantly worse ADC ( p=0.01), 6MWD ( p=0.008) and SGRQ (p=0.01) but not RA950 ( p=0.53) compared with 19 ex-smokers with normal DLCO. Stage I COPD subjects showed significantly worse ADC (p=0.02), RA950 (p=0.0008) and 6MWD (p=0.005), but not SGRQ (p=0.59) compared with subjects with abnormal DLCO. There was a significant correlation for ³He ADC with SGRQ (r=0.34, p=0.02) and 6MWD (r=-0.51, p=0.0002). Conclusions: In ex-smokers with normal spirometry and CT but abnormal DLCO, there were significantly worse symptoms, 6MWD and ³He ADC compared with exsmokers with normal DLCO, providing evidence of the impact of mild or early stage emphysema and a better understanding of abnormal DLCO and hyperpolarised ³He MRI in ex-smokers without COPD. [ABSTRACT FROM AUTHOR]

Noble gas pulmonary magnetic resonance imaging (MRI) is transitioning away from (3)He to (129)Xe gas, but the physiological/clinical relevance of (129)Xe apparent diffusion coefficient (ADC) parenchyma measurements is not well understood. Therefore, our objective was to generate (129)Xe MRI ADC for comparison with (3)He 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, (3)He (b = 1.6 sec/cm(2)) and (129)Xe (b = 12, 20, and 30 sec/cm(2)) 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 (∆SI) ADC differences were evaluated. Compared to never-smokers, COPD ex-smokers showed greater (3)He ADC (P = 0.006), (129)Xe 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 for (3)He ADC (P = 0.02), (129)Xe ADCb12 (P = 0.006), and ADCb20 (P = 0.01), but not for ADCb30 (P > 0.05). ∆SI for never- and ex-smokers was significantly different for (3)He ADC (P = 0.046), but not for (129)Xe ADC (P > 0.05). There were strong correlations for DLCO with (3)He ADC and (129)Xe ADCb12 (both r = -0.95, P < 0.05); in a multivariate model (129)Xe ADCb12 was the only significant predictor of DLCO (P = 0.049). For COPD ex-smokers, CT relative area <-950 HU (RA950) correlated with (3)He ADC (r = 0.90, P = 0.008) and (129)Xe ADCb12 (r = 0.85, P = 0.03). In conclusion, while (129)Xe 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, (129)Xe ADCb12 provided a physiologically appropriate estimate of gas exchange abnormalities and alveolar microstructure., (© 2014 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.)

Purpose: To quantitatively compare hyperpolarized helium 3 (3He) and xenon 129 (129Xe) magnetic resonance (MR) images obtained within 5 minutes in healthy volunteers and patients with chronic obstructive pulmonary disease (COPD) and to evaluate the correlations between 3He and 129Xe MR imaging measurements and those from spirometry and plethysmography., Materials and Methods: This study was approved by an ethics board and compliant with HIPAA. Written informed consent was obtained from all subjects. Eight healthy volunteers and 10 patients with COPD underwent MR imaging, spirometry, and plethysmography. Ventilation defect percentages (VDPs) at 3He and 129Xe imaging were obtained by using semiautomated segmentation. Apparent diffusion coefficients (ADCs) were calculated from 3He (b=1.6 sec/cm2) and 129Xe (b=12 sec/cm2) diffusion-weighted images. VDPs at hyperpolarized 3He and 129Xe imaging were compared with a two-tailed Wilcoxon signed rank test and analysis of variance; Pearson correlation coefficients were used to evaluate the relationships among measurements., Results: 129Xe VDP was significantly greater than 3He VDP for patients with COPD (P<.0001) but not for healthy volunteers (P=.35), although 3He and 129Xe VDPs showed a significant correlation for all subjects (r=0.91, P<.0001). The forced expiratory volume in 1 second (FEV1) showed a similar and significant correlation with 3He VDP (r=-0.84, P<.0001) and 129Xe VDP (r=-0.89, P<.0001), although the correlation between the FEV1/forced vital capacity (FVC) ratio and 129Xe VDP (r=-0.95, P<.0001) was significantly greater (P=.01) than that for FEV1/FVC and 3He VDP (r=-0.84, P<.0001). A significant correlation was also observed for 3He and 129Xe ADC (r=0.97, P<.0001); 129Xe ADC was significantly correlated with diffusing capacity of lung for carbon monoxide (r=-0.79, P=.03) and computed tomographic emphysema measurements (areas with attenuation values in the 15th percentile: r=-0.91, P=.0003; relative areas with attenuation values of less than -950 HU: r=0.87, P=.001)., Conclusion: In patients with COPD, the VDP obtained with hyperpolarized 29Xe MR imaging was significantly greater than that with 3He MR imaging, suggesting incomplete or delayed filling of lung regions that may be related to the different properties of 129Xe gas and physiologic and/or anatomic abnormalities in COPD., (© RSNA, 2012)