Discrepancy between segmentation threshold and first order radiomics

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1

Hello,

Thanks to the advice of Mr. Andras Lasso, I’ve been able to segment the pericardium of the heart (using the Surface Cut option from Slicer). I’ve then applied a threshold to only select the fatty tissue (HU -150 to -50) and it is corretly identified as green pixels on the attached image.
I’ve also checked that this segmentation was correct looking at the label statistics. However, once I run the radiomics on this segment, I noticed that the first order minimum was -346 and the maximum was 73 (outside the range of my initial threshold).

Is this normal? What could cause this difference?
Thank you

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Imagem21920×768 99.8 KB

2

Perhaps I’ve found the solution.
I’ve been playing with the options and I’ve noticed that:

  • when I resample with resampled voxel size 2,2,2 → the result is what is seen above
  • when I do not resample → the first order minimum and maximum are exactly -150 and -50
3

Sounds like the issue indeed. A potential fix is enabling the resegmentationRange in PyRadiomcs this excludes voxels outside the specified range and works like thresholding, but is applied after resampling.