[rowanG077]

Isn't the high number of false positives not just a symptom of us using it almost always on sick people? I would imagine if everyone got their monthly MRI we would learn far more about healthy bodies and the false positive rate would drop.

[drowsspa]

If you scan everyone, the prior probability is the rate of occurrence within your population. So the test has to be more sensitive than that. For things that have an occurrence of less than 1%...