Airspace dimension assessment with nanoparticles as a proposed biomarker for emphysema

Abstract

Airspace dimension assessment with nanoparticles (AiDA) is a novel method to measure distal airspace radius non-invasively. In this study, AiDA radii were measured in 618 individuals from the population-based Swedish CArdiopulmonary BioImaging Study, SCAPIS. Subjects with emphysema detected by computed tomography were compared to non-emphysematous subjects. The 47 individuals with mainly mild-to-moderate visually detected emphysema had significantly larger AiDA radii, compared with non-emphysematous subjects (326±48 µm vs 291±36 µm); OR for emphysema per 10 µm: 1.22 (1.13–1.30, p<0.0001). Emphysema according to CT densitometry was similarly associated with larger radii compared with non-emphysematous CT examinations (316±41 µm vs 291 µm±26 µm); OR per 10 µm: 1.16 (1.08–1.24, p<0.0001). The results are in line with comparable studies. The results show that AiDA is a potential biomarker for emphysema in individuals in the general population.

Airspace Dimension Assessment with Nanoparticles (AiDA) in Comparison to Established Pulmonary Function Tests

“…The distal airspace radius, r AiDA, and zero-seconds recovery, R 0, were within limits of previously measured values. 23 , 24 , 26 About half of all the participants, 359 participants (52%), reported pack-years (1 pack-years = 20 cigarettes smoked per day for one year), above zero. A low number of the participants, 87 individuals (12.5%) had FEV 1 /VC <0.7, which is the GOLD criteria for airway obstruction and COPD.…”

“…Within the study population, 56 individuals (8%) had mild-to-moderate emphysema as visually detected with CT, which was further investigated in another study. 24 Table A1 in the Supplement presents subject demographics and lung examination results for non-smokers (Packyears = 0), smokers (Packyears >0), men and women, respectively. These data show that some indices vary significantly between groups, for instance r AiDA is slightly higher for men than for women (P < 0.01) and higher in smokers than non-smokers (P < 0.05).…”

“…We studied subjects with mild-to-moderate emphysema as diagnosed with CT in another publication. 24 The narrow age range (50–64 years) limits conclusions about the relationship between AiDA variables and possible age-dependencies. The effective airspace radius, r AiDA , was very weakly associated with age (P < 0.01), height (P < 0.01) and pack-years (P < 0.01), both according to Spearman’s rank coefficient and the linear regressions.…”

“…The measured AiDA variables are in accordance with those found in previous AiDA studies. 23 , 24 , 26 Closely related methods include the technique referred to as Aerosol-Derived Airway Morphometry (ADAM). 35 , 36 While certain versions of the ADAM method resemble AiDA, the main difference between the two techniques is that ADAM uses larger particles, typically 0.8–1 µm in diameter and that the ADAM method requires a controlled low breathing flow (typically about 250 mL/s).…”

“…Measurements were performed in a population-based group from the Swedish CArdioPulmonary bioImage Study (SCAPIS). Parts of the AiDA data were published 24 when we investigated the potential of AiDA as a biomarker for emphysema from the difference between r AiDA values in CT-justified emphysematous and non-emphysematous subjects. In the present study, we elaborate further and more broadly on the potential of AiDA in a clinical setting based on multivariate statistical analyses between AiDA variables and standardized lung function measurements.…”