How to retrieve lparam in C# WPF app

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C#

I have a function:

SaveImages(IntPtr Images)

To use it, i have to get Images data.

In C++ Images is got like this:

Images = (ImagesStruct *)lParam;

ImagesStruct is a structure like:

typedef struct _ImagesStruct
{
  DWORD DocNumber;
  CompressedImage *Images;
  BOOL SnippetFront;
}
ImagesStruct;

my question is how to get lParam in C# WPF app to handle an usb connected device (a scaner panini vision x in my case).

i've already created the image struct in c#

What I have tried:

I have found nothing to help until now