synonym but not quite; Usually only the brain should be found inside the cranium... But sometimes you may find a few other things, such as bullets, clots, cysts, brain tumours, or metastases of other tumours. In some cases, the biopsy targets tissues other than specific brain tissues. This is a possibility when the biopsy is performed under fluoroscopic control, for instance.
Now, depending on the context, you will decide whether the term encompasses a wider scope of tissues (i.e. brain), or not.