Getting treatment for someone whose illness prevents them knowing that they have schizophrenia can be tricky. Generally what we do is call the psychiatric intake line and explain the situation. If your son is able to take care of himself and is not harming anyone including himself he can't be treated without his cooperation. This doesn't have to be physical harm, it can be social harms including family harm or being at risk to lose a job. There is a book called "I'm not sick! I don't need help!" that you can read which has some tips on how to convince your son to get treatment.
If he is unable to care for himself or if he is in danger of harming himself or others then he can be brought to the hospital by police or he can be admitted at a hospital. There is more information on the legal issues and how to do this on the BC schizophrenia Society website. Look for a video with Gerrit Clements in the education section. http://Www.bcss.org
Schizophrenia is not diagnosed with a brain scan. Sometimes people have fMRI scans done to rule out other brain problems. There are a lot of things that look like schizophrenia and a doctor needs to figure out what he has. If he has schizophrenia, he will need medication to get well, and the sooner the better for his brain.
I suggest getting in touch with the people I recommended above and speaking with them on the phone to sort out what to do.