Effect of total lung capacity and gender on CT densitometry indexes

Abstract

Objective: Testing the hypothesis that CT densitometry indexes could be influenced by total lung capacity (TLC), gender and height in normal individuals. Methods: In this ethics committee-approved prospective study, 100 healthy non-smoking volunteers who provided written informed consent were included. From a helical scan of the chest, the relative area (RA) of the lung with attenuation coefficients lower than 2960 HU and the 1st and 15th percentiles of the distribution of attenuation coefficients were calculated. Regression lines were drawn between each CT index and volunteers' height and total TLC at CT. Results: In males, there was no statistically significant correlation between any CT index and height. In females, there was a statistically significant correlation between the RA of the lung with attenuation coefficients lower than 2960 HU and the 1st percentile and height but not with the 15th percentile. For both genders, there were significant correlations between all CT indexes and TLC. The relationships between CT indexes and TLC were different in males and females. Conclusion: CT indexes are correlated with TLC and height but more closely with TLC than with height, and differently in males and females. Advances in knowledge: CT indexes are influenced by TLC, gender and height in normal individuals and are more closely correlated with TLC than with height. The relationships between CT indexes and TLC or height are different in males and females. CT indexes used to quantify emphysema should thus be adjusted according to TLC and gender.

Effect of total lung capacity, gender and height on CT airway measurements

“…By considering a group of healthy young adults within a narrow range of age, our study reveals that √WAPi10, WT 3rd and WT 4th are different between genders. Some of these findings confirm those previously reported by Zach et al 8 and Grydeland et al 4 who considered wider ranges of age groups of elderly subjects. Nevertheless, Zach et al 8 arbitrarily selected six third-generation airways and two fourth-generation airways while Grydeland et al 4 selected some airways with an internal perimeter .6 mm without considering their generations.…”

“…The slope of the straight-line relationship between these two measurements was then calculated as well as the value of the square root of the wall area corresponding to an inner perimeter of 10 mm. 4 In addition, the number of third-and fourthgeneration airways actually considered by the reader was recorded. Furthermore, a dedicated program was used to calculate the TLC for each subject based on the volume covered by lung parenchyma.…”

“…1 Several studies reported that these measurements could be useful in the work-up of various diseases such as asthma, chronic obstructive pulmonary disease and cystic fibrosis. [2][3][4][5][6][7] CT airway measurements can be expressed through four indexes: the wall thickness (WT), the lumen area (LA), the percentage of airway area occupied by the wall (WA%) and the square root of wall area at an internal perimeter of 10 mm (√WAPi10). In healthy non-smoking adults, two studies showed that LA and WA% are influenced by age and the total lung capacity (TLC), and WA% by gender, but reported contradictory results concerning the relation between √WAPi10 and gender.…”

“…In healthy non-smoking adults, two studies showed that LA and WA% are influenced by age and the total lung capacity (TLC), and WA% by gender, but reported contradictory results concerning the relation between √WAPi10 and gender. 4,8 These two studies, however, considered subjects older than 50 years among a wide range of age (standard deviations larger than 7 years). 4,8 Moreover, these two studies did not consider the subject's height, whereas a recent study revealed that CT lung densitometry indexes are influenced by TLC, gender and height as well.…”

“…4,8 These two studies, however, considered subjects older than 50 years among a wide range of age (standard deviations larger than 7 years). 4,8 Moreover, these two studies did not consider the subject's height, whereas a recent study revealed that CT lung densitometry indexes are influenced by TLC, gender and height as well. 9 The aim of this study was therefore to investigate the effects of TLC, gender and height on CT airway measurements in healthy young adult volunteers within a narrow range of age.…”