CT-based Airway Flow Model to Assess Ventilation in Chronic Obstructive Pulmonary Disease: A Pilot Study

Abstract

To compare the distribution of pulmonary ventilation assessed by a CT-based full-scale airway network (FAN) flow model with hyperpolarized xenon 129 ( 129 Xe) MRI (hereafter, 129 Xe MRI) and technetium 99m-diethylenetriaminepentaacetic acid aerosol SPECT ventilation imaging (hereafter, V-SPECT) in participants with COPD. Materials and Methods:In this prospective study performed between May and August 2017, pulmonary ventilation in participants with COPD was computed by using the FAN flow model. The modeled pulmonary ventilation was compared with functional imaging data from breath-hold time-series 129 Xe MRI and V-SPECT. FAN-derived ventilation images on the coronal plane and volumes of interest were compared with functional lung images. Percentage lobar ventilation estimated by the FAN model was compared with that measured at 129 Xe MRI and V-SPECT. The statistical significance of ventilation distribution between FAN and functional images was demonstrated with the Spearman correlation coefficient and x 2 distance.Results: For this study, nine participants (seven men [mean age, 65 years 6 5 {standard deviation}] and two women [mean age, 63 years 6 7]) with COPD that was Global Initiative for Chronic Obstructive Lung Disease stage II-IV were enrolled. FAN-modeled ventilation profile showed strong positive correlation with images from 129 Xe MRI (r = 0.67; P , .001) and V-SPECT (r = 0.65; P , .001). The x 2 distances of the ventilation histograms in the volumes of interest between the FAN and 129 Xe MRI and FAN and V-SPECT were 0.16 6 0.08 and 0.28 6 0.14, respectively. The ratios of lobar ventilations in the models were linearly correlated to images from 129 Xe MRI (r = 0.67; P , .001) and V-SPECT (r = 0.59; P , .001). Conclusion:A CT-based full-scale airway network flow model provided regional pulmonary ventilation information for chronic obstructive pulmonary disease and correlates with hyperpolarized xenon 129 MRI and technetium 99m-diethylenetriaminepentaacetic acid aerosol SPECT ventilation imaging.

Anterior Pulmonary Ventilation Abnormalities in COVID-19

“…To assess regional lung ventilation in this patient with CO-VID-19, we used a CT-based full-scale airway network (FAN) flow model. In a previous study, FAN-modeled ventilation showed statistically significant agreements with functional imaging data from participants with chronic obstructive pulmonary disease (2). In this case, we mapped the lesion masks segmented by the Medip COVID19 software to the FAN model geometry to simulate acinar flow alteration induced by COVID-19 infection.…”

Visualization of the Small Airways:What It Is and Why It Matters

“…The limitations of the modeling method presented by Kim et al (2) are still unknown because their method was only demonstrated in nine patients with COPD. However, at a minimum there needs to be validation of this approach with ex vivo histologic examination and/or micro-CT imaging in healthy and diseased lungs.…”

“…Thus, there is a tug-of-war between publishing one's study with access to the code that can be used by others to replicate the results and the desire to have a commercial product. Importantly, the modeling software developed by Kim et al (2) will be made available to other potential users so they can build on their results.…”

“…One group (1) has estimated that there are 274 to 790 million alveoli in the healthy adult lung. In this issue of Radiology, Kim et al (2) describe a visualization method to study the invisible small airways (seven to 30th generation) that move air from the trachea to the peripheral airways and back again for normal ventilation.…”

Flow Volume Loop and Regional Ventilation Assessment Using Phase‐Resolved Functional Lung (PREFUL) MRI: Comparison With 129Xenon Ventilation MRI and Lung Function Testing

“…Due to its capability to directly visualize lung ventilation, pulmonary gas MRI ( 3 He, 10,11 129 Xe, 12–14 19 F 15–17 ) emerged as the reference standard for assessment of regional lung ventilation with MRI. However, a major drawback of pulmonary gas MRI are the associated high costs in terms of human resources, dedicated hardware, and consumables 18 .…”