What code to run before the Dataset Conversion Process(process of creation of nnUNet_raw, nnUNet_preprocessed, nnUNet_results)

[one2clouds]

So before training nnUNet, you first prepare the data using utils.py script inside (Training/fracSegNet/dataset_conversion) folder. But, as I know the dataset is in the format of 001.mha .....100.mha. How come you guys read "_RI_frac.nii.gz" , "_LI_frac.nii.gz" , "_SA_frac.nii.gz" nifti files. Can you provide information about which code you've ran to get nii.gz files from the .mha files?