A lot of the risk factors are related to anatomy or the environment (weather, playing surface, type of footwear), so there's not much that can be done in terms of preventive measures. There is no standardized intervention program for the prevention of non-contact ACL injuries as far as I know. Some studies have been done on certain exercise programs in terms of their effect on decreasing the risk of injury, but nothing conclusive as far as I know thus far. It's not practical to be doing MRIs on a regular basis, nor do I think they would change much in terms of pre-injury risk or overall management.