I am not a doctor and i do not know your particular set of circumstances, but i am guessing the recommended drug is called Tysabri.
That form of treatment seems a tad excessive as it is usually reserved for when all other options fail. I’d be surprised if this was suggested as a ‘first line’ disease modifying drug therapy.
There are other options out there which are far more convenient, far less intrusive and not as ‘hardcore’. I would question why these cannot be considered first.
As for the need for an MRI, i would question that too (especially if getting one entails a long waiting period which would delay the start of any drugs).
The blood test however is necessary and will continue to be needed every 2 or 3 months to ensure whatever drug you start taking is not having an adverse effect (so this is no bad thing!)