Objective quantification of emphysema: Determining best threshold on MDCT 3D volumetry; based on lung function evaluation

PurposeThe aim of this study is to determine the best threshold for MDCT 3D volume evaluation of emphysema based on comparison with lung function and arterial blood gases analysis.Patients and methodsFourteen ex-smoker male patients with chronic obstructive pulmonary disease (COPD) aged 46–79 years, (mean 60.7 years) were assessed using lung function tests. Non-contrast Multidetector CT of the chest was carried out within 1 week of lung function. Results were analyzed using threshold of −900 HU and −950 HU for calculation of emphysema volume and its percentage from total lung volume. 3D quantitative evaluation was done for all patients using an automated protocol and manual tracing technique.ResultsAll patients showed evidence of emphysema on visual assessment. The volume of emphysema was nearly the same between manual and automatic assessment. Positive significant correlation between the volume of emphysema and lung functions was present in 8 parameters at −900 HU threshold while it was present only in 5 parameters at −950 HU threshold.ConclusionMDCT can easily assess the volume of emphysematous lung with positive correlation to lung function testing. Threshold value of −900 HU is more sensitive in the assessment than at −950 HU.