Sensation 16 and 64

Volumetric CT scans of the chest were performed at both maximal inflation and relaxed exhalation.^{14 (link)} Baseline inspiratory CT scans were used in this analysis. Images were acquired with the following CT protocol: for General Electric (GE) LightSpeed-16, GE VCT-64, Siemens Sensation-16 and -64, and Philips 40- and 60-slice scanners with 120kVp, 200mAs, and 0.5s rotation time. Images were reconstructed using a standard algorithm at 0.625mm slice thickness and 0.625mm intervals for GE scanners; using a B31f algorithm at 0.625 (Sensation-16) or 0.75mm slice thickness and 0.5mm intervals for Siemens scanners; and using a B algorithm at 0.9mm slice thickness and 0.45mm intervals for Philips scanners.^{20 (link)} Densitometric assessments of the lung parenchyma were performed on the inspiratory scans using in-house software. Attenuation areas thought to reflect emphysematous destruction of the lung parenchyma were defined as the percent of lung attenuation areas less than -950 Hounsfield Unit (HU) (%LAA-950). LM was calculated on a voxel by voxel basis as described and validated previously.^{21 (link),22 (link)} Briefly, we used the following equation to calculate LM:
$$\text{Lung mass }(\mathrm{g})=\frac{\text{HU}+1024}{1024}\ast \text{Voxel volume}\ast \text{No of voxels}$$

All participants underwent volumetric CT scanning of the chest without contrast in the supine position at coached full inspiration and relaxed exhalation. Data collected from inspiratory CT scans were used to measure adipose tissue compartments. Images were acquired with the following CT protocol: for General Electric (GE) LightSpeed-16, GE VCT-64, Siemens Sensation-16 and -64, and Philips 40- and 60-slice scanners: 120kVp, 200mAs, and 0.5s rotation time. Images were reconstructed using a standard algorithm at 0.625mm slice thickness and 0.625mm intervals for GE scanners; using a B31f algorithm at 0.625 (Sensation-16) or 0.75mm slice thickness and 0.5mm intervals for Siemens scanners; and using a B algorithm at 0.9mm slice thickness and 0.45mm intervals for Philips scanners.^{16 (link)}