Early emphysematous changes in asymptomatic smokers: Detection with 3He MR imaging

Fain, S.B.; Panth, Shilpa R.; Evans, Michael D.; Wentland, Andrew L.; Holmes, James H.; Korosec, Frank R.; O’Brien, Matthew J.; Fountaine, Harvey; Grist, Thomas M.

doi:10.1016/j.rmedu.2006.09.020

Cited by 90 publications

(143 citation statements)

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“…Previous work with micro-CT has established that small airway obliteration and not macroscopic emphysema may be the dominant contributor to airflow obstruction in the early and mild COPD grades (1,2). At the same time, 3 He MRI studies have provided evidence that mild microstructural alveolar remodeling occurs in current-smokers without COPD (12,29) and individuals with no (30) or very mild exposure to cigarette smoke (11). Although it is not known definitively how mild alveolar abnormalities influence airflow, taken together, these previous findings suggest that small airways disease and mild emphysema are both present in elderly never-, ex-, or current-smokers without COPD.…”

Section: Discussionmentioning

confidence: 99%

“…At the same time, however, preclinical or subclinical 3 He ventilation heterogeneity has also been observed in volunteers without clinical signs or symptoms of lung disease such as healthy elderly never-smokers (9), ex-smokers without airflow limitation (10), in second-hand smoke exposed adults (11), and current-smokers without disease (12). To evaluate the underlying anatomic and structural determinants of ventilation heterogeneity, thoracic x-ray computed tomography (CT) has been used to help determine the spatial relationship of airways disease and emphysema with ventilation abnormalities.…”

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confidence: 99%

“…To better understand the pathophysiological features of ventilation heterogeneity in the ''subclinical phase'' of obstructive lung disease in otherwise normal healthy exsmokers, we evaluated a group of well-characterized exsmokers without airflow limitation using both MRI and CT. Because of previous research that has suggested that microstructural alveolar remodeling and small airway obliteration occur in subclinical and mild COPD (1,2,11,12), we hypothesized that in normal ex-smokers, 3 He ventilation abnormalities would be spatially and quantitatively related to a combination of very mild airways disease and emphysema.…”

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Ventilation Heterogeneity in Ex-smokers without Airflow Limitation

et al. 2015

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Ventilation Heterogeneity in Ex-smokers without Airflow Limitation

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“…This enables the tracking of disease progression, such as human chronic obstructive pulmonary disease (1,2) and asthma in mouse models (3). 3 He ADC has been shown to be sensitive to changes in terminal airway anatomy, specifically alveolar damage due to emphysema in both humans (1,(4)(5)(6) and animal models (3,(7)(8)(9).…”

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Mapping of ³He apparent diffusion coefficient anisotropy at sub‐millisecond diffusion times in an elastase‐instilled rat model of emphysema

Boudreau

Ouriadov

et al. 2011

Magnetic Resonance in Med

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Hyperpolarized 3 He gas can provide detailed anatomical maps of the macroscopic airways in the lungs (i.e., ventilation) as well as insight into the lung microstructure through the apparent diffusion coefficient. In particular, the apparent diffusion coefficient of 3 He in the lung exhibits anisotropic effects that depend on diffusion time (d), and it has been shown to be extraordinarily sensitive to enlargement in terminal airways and alveoli associated with emphysema. In this study, the anisotropic nature of the 3 He apparent diffusion coefficient is studied in a rat model of emphysema, based on elastase instillation, specifically for d values less than one millisecond. Hyperpolarized helium 3 ( 3 He) MR imaging can provide both anatomical and functional information that may be important for diagnosing lung diseases. One of the most interesting implementations of 3 He imaging is diffusionweighted MR imaging, taking advantage of the much larger apparent diffusion coefficient (ADC) of 3 He compared to 1.1 Â 10 À5 cm 2 /s for hydrogen ( 1 H). 3 He diffusion in the lungs is restricted by airway and alveolar walls and therefore is highly dependent on lung microstructure. Diffusion measurements are sensitive to lung morphological information such as airway sizes and surface to volume ratio, by measuring the ADC that is largely dependent on lung geometry (1). This enables the tracking of disease progression, such as human chronic obstructive pulmonary disease (1,2) and asthma in mouse models (3). 3 He ADC has been shown to be sensitive to changes in terminal airway anatomy, specifically alveolar damage due to emphysema in both humans (1,4-6) and animal models (3,7-9).The lungs branch off from the trachea to bronchi, bronchioles, and eventually terminate at the alveolar sacs after approximately 25 divisions. The radii of alveoli range from approximately 0.12 to 0.18 mm (10,11) in humans to approximately 0.05 mm alveolar radius in rats (12). The duct size in humans range from 0.22 to 0.60 mm, depending on the generation (10), up to three times the size of an alveoli radius. In this geometry, diffusion is highly restricted for 3 He nuclei as the diffusion lengthis about 0.6 mm given a diffusion time (d) of 1.8 ms, which is typical of diffusion-weighted MR imaging. D 0 in Eq. 1 is the free diffusion coefficient and is equal to 1.91 Â 10 À4 m 2 /s (11) for pure 3 He at room temperature and 0.88 cm 2 /s when diluted in air. It has been shown that 3 He ADC obtained at millisecond diffusion times can distinguish normal from emphysematous tissue and correlates with mean linear intercept histology, an accepted measure of alveolar damage (12,13). 3 He ADC values obtained at sub-millisecond diffusion times (14) are expected to be even more sensitive to emphysema, especially in small animals. At longer diffusion times on the order of seconds, 3 He ADC is expected to reflect changes in lung anatomy over much larger length scales on the order of centimetres. Recent work has demonstrated ADC sensitivity to collateral pathway changes...

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“…(190) ADC is homogeneously distributed in normal subjects, and becomes progressively more heterogeneous with normal smokers to emphysema (191)(192)(193)(194). ADC has been shown to increase under the influence of aging (195,196), emphysema (194,197,198) and due to gravity dependent compression of the lung (199); Figure 11). A significant issue is the fact that ADC measurements can only take place in areas where 3-He signal is present.…”

Section: Hyperpolarized Gas Imagingmentioning

confidence: 99%

Functional Imaging: CT and MRI

Beek

Hoffman

2008

Clinics in Chest Medicine

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Synopsis-Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled MDCT allow for quantification of presence and distribution of parenchymal and airway pathology, Xenon gas can be employed to assess regional ventilation of the lungs and rapid bolus injections of iodinated contrast agent can provide quantitative measure of regional parenchymal perfusion. Advances in magnetic resonance imaging (MRI) of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized helium imaging, which can allow imaging of pulmonary ventilation and .measurement of the size of emphysematous spaces.

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Early emphysematous changes in asymptomatic smokers: Detection with 3He MR imaging

Cited by 90 publications

References 0 publications

Ventilation Heterogeneity in Ex-smokers without Airflow Limitation

Ventilation Heterogeneity in Ex-smokers without Airflow Limitation

Mapping of ³He apparent diffusion coefficient anisotropy at sub‐millisecond diffusion times in an elastase‐instilled rat model of emphysema

Functional Imaging: CT and MRI

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Early emphysematous changes in asymptomatic smokers: Detection with 3He MR imaging

Cited by 90 publications

References 0 publications

Ventilation Heterogeneity in Ex-smokers without Airflow Limitation

Ventilation Heterogeneity in Ex-smokers without Airflow Limitation

Mapping of 3He apparent diffusion coefficient anisotropy at sub‐millisecond diffusion times in an elastase‐instilled rat model of emphysema

Functional Imaging: CT and MRI

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Mapping of ³He apparent diffusion coefficient anisotropy at sub‐millisecond diffusion times in an elastase‐instilled rat model of emphysema