Table 1.
Quantitative measurements computed from the CT scans. Number of features are indicated between parenthesis
| Name | Description |
|---|---|
| idistTIα a | Length of the ray cast from the center of the trachea to the border with an angle α in inspiration (4) |
| ES | Percentage of voxels inside each lobe with CT values below −950 HU in inspiration (5) |
| Pi10 | Square root of the wall area of a hypothetical airway of 10mm internal perimeter (1) |
| idistα b | Length of the ray cast from the center of the trachea to the border with an angle α in inspiration (4) |
| edistα b | Length of the ray cast from the center of the trachea to the border with an angle α in expiration (4) |
| AS | Percentage of voxels in each lobe with CT values below −856 HU in expiration (5) |
| medRatio | Median of the ratio of the CT values at expiration to the CT values at inspiration per lobe (5) |
| prmES | Percentage of voxels in each lobe with CT values below −950 HU in inspiration and below −856 HU in expiration (5) |
| prmAS | Percentage of voxels in each lobe with CT values above −950 HU in inspiration and below −856 HU in expiration (5) |
a
This is used in inspiration only, and the section selected is the one with the minimum tracheal index (TI).
b
b This is used when inspiratory and expiratory scans are available, and the section selected is the one with the minimum T.