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

2. http://www.ajnr.org/content/early/2014/11/27/ajnr.A4173.full...