Am extremely claustrophobic..can i get general iv sedation for a head mri? must be asleep. will i need a radiologist or nurse anesthetist present?

Yes you can: Certain facilities can provide MRI with sedation under the direction of an anesthetist.

Unlikely: Outpatient MRI very unlikely scenario and generally you have to bring self in/out, so only oral / mild level sedation. Consider an "open" MRI for less confinement. If truly a severe affliction, must be set up well in advance and usually done in hospital facilities for access to anesthesia expertise and in case of any complications. Discuss options with your dr.