How to load a raster back into a raster dataset without file I/O?

I have this fairly complex routine running as a service. All was well right up until I called one of the methods and instead of returning a RasterDataset as an IGeoDataset it returned an IRaster as the IGeoDataset. I need a consistent way of passing this modified raster throughout the code and I was using a RasterDataset for doing that. But no matter what I do I cannot get that modified raster into the dataset without (apparently) saving it to disk. I want to avoid this since File I/O on a service is evil. And ESRI doesn't have modern software so it does not take a stream as input for loads preventing me from using a memory stream.

So any suggestions on how to load the modified raster back into the RasterDataset without saving to disk?