If you are hunting for a gross change, sure, go get scanned. For example, a calcium scan is generally a good thing--learning that your arteries are 50%+ blocke

If you are hunting for a gross change, sure, go get scanned. For example, a calcium scan is generally a good thing--learning that your arteries are 50%+ blocked will save your life. However, the kind of detail you require to catch something small, early requires an MRI--generally with a contrast dye. Unfortunately, Gadolinium, for example, seems to bioaccumulate. So, just like X-Rays, how many MRI's do you need to get over your life before the MRI is more problematic than the thing you are looking for? And this is before you start getting into what emotional toll that "spotting something" will have on the patient. A friend of mine had "something" on her mammogram and the anxiety combined with high-blood pressure spike that induced until the biopsy came back negative could very well have given her a stroke. The worst part is that people want to do all this "medical" stuff when there are much better low-hanging fruits: eat better, exercise, sleep, get vaccinated (viruses cause more damage than you think), etc.