# Calculate MEAN, SD

**URL:** https://discourse.slicer.org/t/calculate-mean-sd/36301
**Category:** Support
**Created:** [May 21, 2024, 3:04pm UTC](https://discourse.slicer.org/t/calculate-mean-sd/36301 "2024-05-21T15:04:44Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Vikram](https://avatars.discourse-cdn.com/v4/letter/v/e47774/32.png) [@Vikram](https://discourse.slicer.org/u/Vikram)
#### Post date: [May 21, 2024, 3:04pm UTC](https://discourse.slicer.org/t/calculate-mean-sd/36301/1 "2024-05-21T15:04:44Z")

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it is possible to calculate mean and SD and HU to draw ROI BY using 3d slicer.  
if it is possible any one can guide me , how i can count

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<div class="post-metadata">

### Author: ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)
#### Post date: [May 21, 2024, 5:30pm UTC](https://discourse.slicer.org/t/calculate-mean-sd/36301/2 "2024-05-21T17:30:40Z")

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If you create a segmentation for your ROI, this example script shows how to extract voxel information for that specific region as a vector. then you can simply use standard mean or sd function to calculate.

[Script repository — 3D Slicer documentation](https://slicer.readthedocs.io/en/latest/developer_guide/script_repository.html#get-the-values-of-all-voxels-for-a-label-value)

You can also use the Segment Statistics to calculate the mean intensity inside the segment, but I am not sure if it does SD.