Initially, I excluded all imaging, codec, HL7 and network functionality in order to make the library build at all in Silverlight.
Just now I have begun looking at porting the mdcm image handling to Silverlight. The mdcm library uses the .NET System.Drawing library for image handling, which is not available in Silverlight. However, I have modified the source code so that when it compiles for Silverlight, it instead uses the BitmapSource and WriteableBitmap classes from the System.Windows.Media.Imaging namespace.
The added benefit of these modifications are that they are equally applicable to WPF, i.e. it would be a simple task to switch from Windows Forms (which the original mdcm library depends upon) to WPF, given these Silverlight motivated modifications.
I have not explicitly made any WPF adaptation yet, but this is clearly worth future exploration.