This isn't a commonly used term, but I think it refers to flattening of the coronary sinuses. In someone who is 31 years old, this may mean that there is abnormality in the makeup of the aortic wall. This further may imply that there is aortic valve stenosis. Getting an echocardiogram will help define the aortic valve and the proximal aorta and it's an excellent starting test. An MRI would be more accurate if more testing is needed. I would not recommend a CT scan in someone this young because of the radiation exposure associated with it.
You're right- Ct or MRI would reveal a lot more and more exacting info. I have discovered that this is related to aortic aneuysm.