Pen
To mark specific regions on the image by drawing segmented lines:
Click Diagnose in the menu bar.
Click Pen 
.
Draw line segments by clicking where the anchor points have to come.
Note
The pen annotation line thickness can be chosen.
Right-click to finish.
All the lines will appear as one annotation to the Annotation tab 
on the smart panel. Click 
to change the color or delete the lines.