Table 3.

Steps for GLS Measurement Common to Various Software

Step 1	Image choice: select the best image acquired for each view for analysis.
Step 2	Event timing: define timing of end-systole (see Calculation of GLS to define)
Step 3	Software border detection: automated vs. semi-automated tracing with fiducial marking of the mitral annulus and apex. Ensure that the contour borders do not extend pass the mitral annulus into the left atrium.
Step 4	Tracking quality: visually inspect the moving images to determine the adequacy of tracking; check that the software tracing actually moves with the underlying myocardium. Manually adjust ROI or endocardial contour to optimize tracking if necessary. Exclude segments that do not adequately track after 3 attempts to optimize.
Step 5	Analysis: after speckle tracking is performed in the 3 apical views, the strain values for all the segments are integrated to obtain GLS. Visually inspect the curves from each view for any segment that is a clear outlier.
Step 6	Verification: if there are clear outliers in the examination of the strain curves, return to the tracking to ensure that the image quality in that segment is appropriate and that tracking is accurate.

GLS = global longitudinal strain; ROI = region of interest.