Here is how I did it:
This was easier for me than trying to figure out the specific regex necessary.
int indexPictureData = result.IndexOf("-PictureData:");
int indexIdentity = result.IndexOf("-Identity:");
string returnValue = result.Remove(indexPictureData + 13);
returnValue = returnValue + " [bytecoderemoved] " + result.Remove(0, indexIdentity); `