What does redemonstration of a patent splenic artery aneurysm maximum dimension on contrast enhanced images is 19mm mean?

Little bulge: "Redemmonstration" means it's been seen before, hopefully a while back, because that means it's stable and not growing. The aneurysm is a bulge in the artery to your spleen. This can rupture, which is sometimes fatal. 19mm isn't very big, but it's big enough to do something about it. We now have endovascular repair methods, so you wouldn't need surgery. But I recommend you take care of it!