What clinical or imaging features help distinguish intracranial atherosclerotic disease from intracranial dissection in the setting of an LVO?

This is a great question and very difficult to answer. I think the first thing I look for is whether there is significant atherosclerosis elsewhere. Lack of significant atherosclerosis elsewhere with a single significantly stenotic intracranial lesion in a young person or someone without significant risk factors should raise concern for dissection. Sometimes a dissection flap can be seen with DynaCT. A dissection protocol MRI may be able to show an intramural hematoma, which would indicate dissection. MR vessel wall imaging will show eccentric wall thickening with variable plaque enhancement for athero and dissection will show the intramural hematoma, and you may be able to see a dissection flap. In general, dissections will be more tapered...