Fig. 5From: Quantitative CT analysis using functional imaging is superior in describing disease progression in idiopathic pulmonary fibrosis compared to forced vital capacityCorrelation between Forced Vital Capacity (% predicted) and FRI-determined fibrotic tissue (% predicted) measured at Total Lung Capacity (TLC) for upper and lower lung zones. Fibrotic tissue is determined from the scans based on segmentation of areas with Hounsfield Units between − 600 and 600Back to article page