CT and Functional MRI to Evaluate Airway Mucus in Severe Asthma

CT Evidence of Airway Luminal Plugging in COPD

“…This finding clearly raises important questions about how to regionally evaluate and treat COPD. It is also important to note that the observation of plugs in COPD is similar to findings reported in asthma, 8,9 although the prevalence reported in COPD is much lower, and notably there are differences in the scoring system used. Obviously, it will be important to take these differences into consideration and to use the same CT acquisition protocols and scoring methods in any direct comparisons in the future.…”

Response

“…With great interest, we read the article by Svenningsen et al in a recent issue of CHEST (June 2019) on CT scanning and functional MRI to evaluate airway mucus in severe asthma. 1 We understand their results, but would like to ask the authors two questions. First, the authors included as study subjects "patients with severe asthma."…”

“…We thank Drs Okauchi, Yamada, and Satoh for their pertinent questions in response to our multimodality imaging study designed to better understand the functional consequence of intraluminal contributors to airway obstruction in patients with severe asthma. 1 We measured airway eosinophils (as the sputum eosinophil percent) and airway mucus (as the CT mucus score 2 ) and observed that they both can contribute to ventilation abnormalities (identified by MRI) that persist after bronchodilator administration in patients with severe asthma. Our observations certainly support the prevalence of mucus plugging in patients with severe asthma and their functional relevance, as patients with asthma and mucus plugging have worse ventilation.…”

“…We read with interest the paper by MacMahon et al 1 in an issue of CHEST (July 2019) comparing the accuracy of experienced thoracic radiologists and trainees vs the PanCan (Vancouver) Risk Prediction model 2 to estimate the likelihood of malignancy of lung nodules found by using screening CT imaging.…”

“…The size and proportion of solid, nonsolid, and part-solid nodules were not provided in the article. 1 Matching the size of malignant nodules with benign nodules with a cancer prevalence of 20% instead of the 1% to 2% in the screening setting is expected to reduce the area under the curve of any risk prediction model that is based on a much lower cancer prevalence. Most of the screen-detected lung nodules are # 10 mm.…”