Hello,
I am new in 3D slicer and I could not find out how I can create a line profile? I already used a ruler to create a line but it does not show a line profile.
I am thankful for your help!
With kind regards,
Mahrukh
You can get intensity profile along a line using Line Profile module in Sandbox extension.
Where can I find the „Sandbox“ extension? Because if I click on „Extensions“ there’s no „sandbox“ 
Please check again. It is between SPHARM-PDM and and ScatteredTransform extensions in the list. You can also type sandbox in the search box to find it.
If you still cannot find it then let us know what Slicer version and operating system you use.
A very similar question has just been asked and answered in this topic, too: