in order to running simpleITK on CSharp follow these instruction first
first of all follow these instruction for adding simple itk dll in your project:
https://itk.org/Wiki/SimpleITK/GettingStarted/A_visual_guide_to_SimpleITK_with_CSharp
Copy the program.cs in this repository to your project set your directory and then Run the project
the Dicoms2Mhd convertor is available in this repository:
https://github.com/jifaley/Dcm_to_Mhd
also you can find python conversion of Mhd to Dicoms here:
https://simpleitk.readthedocs.io/en/master/link_DicomSeriesFromArray_docs.html