Vin,

Christine said it, not sure why he wants an MRI when a biopsy is the only way to know if it's cancer or not. If he's examined the area and not found nor felt anything suspicious you only have 2 choices, a biopsy or wait it out and monitor.

PET's are fallible as stated several times above, just keep that in mind. I was in the same situation in spring of this year, unlike Christine I waited it out and the next test came clean. My policy in business though was always error on the side of caution.

Good luck

Eric