Use the Markup Ratio Caliper tool to create a ratio measurement of two lines on an image. For example, you can use this tool for thoracic ratio measurement by drawing the first line to represent the width of the thoracic cavity and the second line to represent the width of the cardiac silhouette.
To create a ratio measurement
From the Image area top toolbar, Markup button menu, select Markup Ratio Caliper.
Click the start point of the first line to measure.
Move the pointer to the end point of the first line and click.
Click the start point of the second line to measure.
Move the pointer to the end point of the second line and click.
The ratio measurement is displayed as "Ratio: x.xx", where x.xx is the value of the first line divided by the second.
To change a line length, drag one of the control points to a new position.
The ratio measurement is updated to reflect the new line length.
To set the measurement, right-click.
The measurement values and units used depend on the calibration applied or available to the study. Refer to Understanding measurement values and units used.
To delete the lines, press the Delete key.