Fig. 1

Overview of the proposed integrated method. a Construction of the normal database, producing lung volumes and recalibrated density values from a normal population; b Input data from an emphysema patient to be evaluated; c Calculation of recalibrated density data and predicted CT lung volume of a patient; d Normalization and volume correction of the density values, resulting in a Z-score for lung tissue mass: Standard Mass Score (SMS). In this particular example, a seemingly abnormally low lung density (PD15) can actually fall within the normal range for tissue mass, after accounting for different CT scanners (i.e. recalibration of lung density values) and lung volumes (volume correction)