Fig. 2
Methods for measuring diaphragm function parameters at the end of maximal breathing. The image shows a single frame of the right sagittal magnetic resonance imaging data for one participant. The lung area, which is the area inside the lung contour (coloured blue) at the end of inspiration (a) and expiration (b). a1, a2 present the upper-lower diameters, which was the vertical distance between the lung apex and hemidiaphragm is measured at end of inspiration (a1) and expiration (a2), and the two dimensions are subtracted to obtain the diaphragmatic displacement by length (a1–a2). b1, b2 present the anterior–posterior diameter of the chest, which was the trans-vertical anteroposterior dimension of the upper and lower thoraces at the right mid-sagittal planes measured at end of expiration (b2) and inspiration (b1), and the two dimensions are subtracted to obtain the chest wall motion (b1–b2). The white arrow shows the diaphragm thickness (DT) at the end of maximal inspiration (e1) and expiration (e2). c1 presents the diaphragm length, which is the length across the diaphragmatic dome from the anterior to the posterior chest wall margin at the end of maximal inspiration. c2 presents it at the end of maximal expiration; d1 presents the linear distance of the anteroposterior costophrenic angle at the end of maximal inspiration; d2 presents it at the end of maximal expiration. Diaphragmatic dome factor (ins) = c1/d1. Diaphragmatic dome factor (exp) = c2/d2. Diaphragm thickening fraction (DTF) = (DT at end of maximal inspiration) – (DT at end of maximal expiration)]/ (DT at end of maximal expiration) × 100%