Intriguing post. But when it comes to retrospective analysis you can only use methods that were already available at the time when the exam was originally performed. The same way I cannot sue the physicians of my late grandfather for not trying thrombolysis when he had an acute stroke, it is not possible to take legal action by relying on a then nonexistent algorithm. What needs to be demonstrated is that a human observer of the day working with the then state of the art medical knowledge could have described it as abnormal. Then again this varies a lot by jurisdiction.