MRI after cortison?

[Miia]

Please, could someone help me quikly. I am so confused and so do the doctors I think.

Does anyone of you know, how long time you have to wait after cortison (1 g 3 days) to get an MRI?

I've heard under 7 weeks is not enough and you should wait 2-3 months. I mentioned under 7 because I could be having a spinal MRI then, but now the same doctor says it's not enough. Or, she didn't even check it in the first place. It was me who started to doupt it.

What then IS enough or should I just take the 7-week-MRI and hope cortison has no effect on it anymore???