I agree.. A biopsy is necessary to know for sure. Why wait go through an MRI only to have to have it biopsied regardless? That's the only way for a firm dx... Would you let them treat him without a biopsy? Unless of course you were almost certain it was a recurrence? Would they treat him without a biopsy? And since MRI's ct's and PETs all respond to similar things, infection, healing, inflammation what does your ENT hope to gain by making you wait? Plus - how comfortable would you be waiting? To see if it grows or spreads?
Good luck...

and hugs and do breath. It could just be an area of inflammation.