There is no cast defined to let you use a Bitmap as an imagestatistics class - and since they are completely unrelated classes to even start writing wone would be complicated as you would have to fully understand both classes in order to process the Bitmap and extract the statistics information from it.
This is particularly the case when Bitmap is a .NET class, and imagestatistics is a Java class and the two do not even share a common framework:
ImageStatistics (ImageJ API)[
^]
I have no idea why you think that would work: you can't even directly use Java classes in a .NET application, or vice versa