Emphysematous changes and normal variation in smokers and COPD patients using diffusion 3He MRI

Ventilation Heterogeneity in Ex-smokers without Airflow Limitation

“…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.…”

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

“…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).…”

“…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)(5)(6) and animal models (3,(7)(8)(9).…”

Functional Imaging: CT and MRI

“…The ratio of these polarization changes allow the spatial mapping of ADC, with higher values allocated to larger air spaces (such as trachea and large bronchi). (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).…”