Fig 4.

Software screenshot depicting one bronchial cross-section analysis result. The blue spokes depict the inner wall boundary (IW) and the red spokes delineate the outer wall extent (OW) as calculated by the mirror-image Gaussian fit (MIGF) method. Since statistical validation was used, only spokes with measurements falling within 2 standard deviations of the mean are retained, and all other measurements are rejected. Note that the bronchus being analyzed is in close proximity with surrounding soft tissue and vessels along some of its circumference. The MIGF method allows the calculation of the true bronchial wall thickness even along segments of the bronchial wall edge that are obscured by soft tissue in close proximity. Statistical validation results in the selection of a representative sample of measurements around the bronchus.