If they’re going to make a scan of your brain then yes you will most likely need to use contrast dye in the MRI otherwise the doctors simply will not be able to see what is going on. It’s usually only when they are looking for big and obviously shaped things that they might not need the contrast dye.
Generally speaking, before an MRI the doctors usually ask you to do a blood test, they use this among other things to see if you have any kidney problems and might be at risk for complications from the contrast dye, because that usually only happens to people whose kidneys are unable to process the dye quickly enough.
I had an MRI done of my brain two years ago and I had no problems with the dye. Most people don’t. It’s obviously worth reading up on the risks and maybe you feel better if you call the doctor and ask which contrast dye they’re going to use in your case and have some ability to read up on it.
To be honest with you, I think you don’t need to worry about it, but caution is never bad and it’s probably a good idea to have an informed discussion with your doctor about it and to confirm with them if they properly assessed whether it’s safe for them to administer the contrast dye to you.