In case you find runtime exception like

Decoding dataset with transfer syntax: JPEG Lossless, Non-Hierarchical, First-Order Prediction (Process 14 [Selection Value 1]): Default Transfer Syntax for Lossless JPEG Image Compression is not supported

then check those things:

Is the Transfer Syntax supported on your platform

Check this wiki page Supported-Transfer-Syntaxes if fo-dicom provides an encoder/decoder for your platform.

if you are building netcore and running on linux, then you can also take a look at https://github.com/Efferent-Health/Dicom-native. They shared their codec that runs on every netcore platform.

Is the build architecture set

When installing fo-dicom via NuGet, a build script fo-dicom.targets is inserted into the Visual Studio project. This build script is responsible for fetching the Dicom.Native*.dll associated with the current build architecture to the build output (/bin) folder.

The fetch procedure only works if the build architecture of the project is set to either x86 (fetches Dicom.Native.dll) or x64 (fetches Dicom.Native64.dll), otherwise you will be prompted in the build log to select an appropriate build architecture.

This means that, when installing via NuGet, you will be able to sufficiently build your fo-dicom referencing application or class library even in the Any CPU architecture setting, but you will not be able to access the native codecs since these libraries will not be copied to the build output folder. To sufficiently access the native codecs via your application, please make sure that the project build architecture is set to x86 or x64.