Fig. 4
From: Diaphragm assessment by two dimensional speckle tracking imaging in normal subjects
Longitudinal strain of diaphragm during inspiration. The x-axis represents time (millisecond), and the y-axis represents longitudinal strain (%). Strain is a measure of relative deformation and is a negative value. In this example, the central portion of the region of interest (depicted in blue in the ultrasound image at the upper-left corner) was traced and measured as – 46.4 % (displayed in the column below the x-axis). The more negative value means the higher degree of deformation (contraction)