Click the measuring tool menu drop-down arrow to view the tools. It consists of the following 4 tools.
The length tool is used to determine the linear distance in mm between two locations.
The bidirectional tool is used to determine the longest diameter (LD) and longest perpendicular diameter (LPD) in mm.
The annotation tool is used to add a qualitative marker.
The ellipse tool is used to calculate the elliptical area in mm2 and Hounsfield Units (HU).