Fig. 5
From: Ultrasound and non-ultrasound imaging techniques in the assessment of diaphragmatic dysfunction
Reproduced under Open Access Creative Commons License: Orde et al. BMC Anesthesiol 2015;16(1):43
Two-dimensional speckle tracking imaging of the diaphragm’s zone of apposition at end-exhalation (left panel) and end-inhalation (right panel). The image of the diaphragm has a granularity caused by an inherent ultrasound artifact known as speckle. A cluster of speckles form a kernel. The stronger the contraction of the diaphragm, the closer kernels come together (strain). With speckle-tracking software, it is possible to quantify the strain of the diaphragm as: 100 multiplied by the difference of the distance between two representative kernels at end-inhalation (D2) minus the distance between the same kernels at end-exhalation (D1) divided by D1. In the example above, the distance between two representative kernels at end-exhalation (left panel) is 10 mm (D1) and at end-inhalation (right panel) 6 mm (D2), yielding a strain of -40%.