Compared with what?
As a report reader I find a “Comparison:” section more cosmetic than useful. But if used, at a minimum state body-part and modality in addition to date.
I don’t find listing comparison exams as helpful as reporting them in-line. For example, it is easier (and quicker) to comprehend “Tumor unchanged from 5/14/14 chest CT” than “Tumor unchanged from the comparison CT”. In the second example the reader must refer to the “Comparison:” section. This distracts their attention, takes more time, and slows comprehension,