CT imaging biomarkers beyond lung nodules
coronary calcification
OSTEOPOROTIC FRACTURE, EMPHYSEMA
To address the 4th objective, CT imaging biomarkers beyond lung nodules will be measured. Emphysema, coronary calcification, bone density, vertebral height and body composition will be assessed on baseline and incident round CT scans using AI-Rad companion Chest (Siemens Healthineers). Emphysema will be expressed by 15th percentile Hounsfield units (HU) of low attenuation voxels (Perc15) and the percentage of low-attenuation voxels below − 950HU. For coronary calcification, the calcium volume score will be measured. The CT density (in HU) of thoracic vertebrae will be used as measure of bone density; height of the vertebrae will be measured to assess osteoporotic fractures [In a subset of 250 subjects with a short-term repeat CT, AI-based segmentations of baseline and short-term repeat CT scans will be visually checked for accuracy. The AI-software will be run on the baseline and short-term interval scan to re-evaluate the biomarkers, and assess repeatability and inter-scan variability. Based on the results, rules will be derived for checking AI results in the remaining NELSON scans. In addition, randomly AI segmentations/results will be visually checked for every 1 in 100 scans.