Difference in the airway luminal area between the standing and supine positions using upright and conventional computed tomography

Abstract

No clinical studies to date have compared the airway luminal area between supine and standing positions. Our aim was therefore to compare the airway luminal area between these two positions on computed tomography (CT) and to determine its correlation with forced expiratory volume in 1 s (FEV1). Thirty-two asymptomatic volunteers underwent both conventional (supine position) and upright (standing position) CT during deep inspiration breath-holding. Pulmonary function tests were conducted on the same day. We measured the airway luminal area on CT in each position. Paired t-tests and Pearson's correlation coefficients were used for statistical analysis. The average luminal areas of the trachea, right and left main bronchi, and average third-generation airway were greater in the standing than the supine position by 3.4%, 6.1%, 5.5%, and 5.2%, respectively. The correlation coefficients between airway luminal areas and FEV1 tended to be higher in the standing than the supine position; this correlation was highest for the average third-generation airway (r = 0.70, P < 0.0001). The airway luminal areas of the trachea, bilateral main bronchi, and average third-generation airway were greater in the standing than the supine position. The average third-generation airway area in the standing position had the highest correlation with FEV1.

Comparison of inspiratory and expiratory airway volumes and luminal areas among standing, sitting, and supine positions using upright and conventional CT

“…and 7 (Y.YO.) years of experience using a commercially available workstation (Synapse Vincent, Fuji Film Co., Ltd., Tokyo, Japan) 3 , 4 , 10 – 15 . This workstation incorporates a computer-aided detection system and automatically extracts the entire airway tree (from the trachea to all bilateral airways with lumen diameters of more than approximately 1.5 mm), which was defined as the airway volume (Fig.…”

“…This workstation incorporates a computer-aided detection system and automatically extracts the entire airway tree (from the trachea to all bilateral airways with lumen diameters of more than approximately 1.5 mm), which was defined as the airway volume (Fig. 2 ) 3 , 4 , 10 – 15 . In addition, all branches of the third- to sixth-generation airways in all segments were manually identified by tracking from the third to sixth generation 13 , 15 , 16 .…”

“…2 ) 3 , 4 , 10 – 15 . In addition, all branches of the third- to sixth-generation airways in all segments were manually identified by tracking from the third to sixth generation 13 , 15 , 16 . The cross-sectional images perpendicular to the longitudinal center line of the lumen were generated for each branch, and the luminal areas in the middle-third portion were automatically measured and averaged 10 , 13 , 15 .…”

“…The cross-sectional images perpendicular to the longitudinal center line of the lumen were generated for each branch, and the luminal areas in the middle-third portion were automatically measured and averaged 10 , 13 , 15 . The mean luminal area for each generation airway was calculated in all segments 10 , 15 . All measurements were performed in a blinded and randomized manner.…”

Differences in lung and lobe volumes between supine and upright computed tomography in patients with idiopathic lung fibrosis

“…Lung and lobe volume measurements using CT. Lung and lobe volume measurements on CT for all 24 patients in each position were performed by a pulmonologist with 11 years of experience (S.C.) using a commercially available workstation (Synapse Vincent; Fuji Film Co., Ltd., Tokyo, Japan) 12,18,19,[24][25][26] . This workstation incorporated a lobar computer-aided diagnosis (CAD) system that was previously demonstrated to precisely measure lobar volumes 12,18,27 .…”