Figure 2

Individual changes of VRI image score during and at the end of NPPV treatment. 1 Similarity: The similarity of vibrational energy curve (VEC) among respiratory cycles. 2 Inspiratory steep: Steep peak in VEC caused by sudden increased energy during inspiratory phase. 3 Plateau: Platform in VED, representing little change in vibrational energy. 4 Sag: Concave segment in VED. 5 Low and flat expiration (LFE): low and flat segment in VED during expiration phase. 6 Unsmooth edge of MEF image. 7 Midline bending of MEF image. 8 MEF image defect: abnormal decreased or absent gray-scale intensity in MEF image. 9 Pneumatocele: abnormal increased gray-scale intensity in MEF image. 10 Image jumping: rapid and discontinuous shift of the energy center in dynamic VRI. 11 Occurrence and development disorder: abnormal evolution of the dynamic VRI. In normal subjects, the dynamic VRI appears from upper medial to lower lateral, and disappears from lower lateral to upper medial. 12 Asynchronization: the evolution of bilateral lungs is asynchronous in dynamic VRI. 13 Lag: the dynamic changes of VRI in one lung falls behind another one). 14 Inverse dominance: the dominant side of VRI intensity inverted when breathing cycle changes from inspiratory phase to expiratory phase. 15 Pneumatocele at inspiratory phase: abnormal increased gray-scale intensity in MEF image at inspiratory phase. 16 Pneumatocele at expiratory phase: abnormal increased gray-scale intensity in MEF image at expiratory phase. 17 EVP synchronization: temporal synchronization of EVP between bilateral lungs. 18 EVP difference: amplitude difference of EVP between bilateral lungs.