3D ultrashort echo-time Cones is tested against PROPELLER for lung density detection in paediatric cases on two cohorts: patients with morphologically normal lungs and patients with Cystic Fibrosis. Cones seems to be able to detect lung density based on lung-to-background signal intensities ratio (LBR) while PROPELLER fails to show any correlation. Cones is able to show the lung anteroposterior gravity gradient as well. There was no difference between Cones LBR of controls and CF while pixel-intensity histogram analysis of Cones slices seem to differentiate pathological from normal lung. Qualitatively, lung constrast decreases with increasing age.