This can be true even if there's something "obvious" on the MRI, since the importance really depends on the base rates of that abnormality in healthy individual

This can be true even if there's something "obvious" on the MRI, since the importance really depends on the base rates of that abnormality in healthy individuals without symptoms[1]. For example, it's easy to find bulging discs when looking for the cause of back pain, but bulging discs are also very common in asymptomatic individuals[2]. 1. https://arbital.com/p/bayes_rule/?l=1zq https://arbital.com/p/bayes_rule/?l=1zq 2. http://www.ajnr.org/content/early/2014/11/27/ajnr.A4173.full.pdf http://www.ajnr.org/content/early/2014/11/27/ajnr.A4173.full...