This question is to radiologists. I'm a PhD student in medical image processing and (I thought that) I was working with 3D-DSA images obtained by subtraction of non-contrast enhanced CBCT from a contrast enhanced one. Now I see here and there people mention 3DRA modality. Is this actually just a different word for the same thing? If so, which one is a standard one (could not find either in DICOM standard text for example)?