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It has been known for several years that airflow limitations in the small airways may be an important contributor to
Chronic Obstructive Pulmonary Disease (COPD). Quantification of wall thickness has lately gained attention thanks to
the use of high resolution CT, with novel approaches focusing on automated methods that can substitute for visual
assessment [1, 2]. While increased thickening of the wall is considered evidence of inflammatory disease, we
hypothesize that there may be additional ways to detect and quantify inflammation, specifically the uptake of contrast
material. In this preliminary investigation, we selected patients with documented chronic airway inflammation, and for
whom pre and post contrast datasets were available. On targeted reconstruction of right upper and lower lobes, we
selected airways with no connections to surrounding structures, and used a modified Full-Width-Half-Max method for
quantification of lumen diameter, wall thickness, and wall density. Matching airway locations on the pre- and postcontrast
cases were compared. Airways from patients without airway disease served as a control. Results for the airway
disease cases showed an average enhancement of 72 HU within the airway walls, with a standard deviation of 59 HU. In
the control group the average enhancement was 16 HU with standard deviation of 22 HU. While this study is limited in
number of cases, we hypothesize that quantification of contrast uptake is an additional factor to consider in assessing
airway inflammation. At the same time we are currently investigating whether enhancement can be measured via a
"contrast" map created with dual energy scanning, where a 3-value decomposition algorithm differentiates iodine from
other materials. This technique would eliminate both the need for a pre-contrast scan, and the task of matching airway
locations on pre- and post- scans.
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