Re: When you're the pt or family member
Let me see if I can help;
I have worked radiology and did the sedation for the kids both CT and MRI. For routine outpatient with kids and healthy adults we do not screen kidney function, it's a standard for sick hospitalized patients, not healthy ones. An RN will give the sedation, stay with your child, monitor them after and have specialized training (ACLS and others). The sedation starts to wear off in 30 minutes.
To be honest, it makes no sense to do either scan at 18 months without sedation as you won't get any pictures with movement and have to reschedule, or worse, pay for an inconclusive test "with motion" and have to go again and now sedate.
It's not uncommon for a primary doc to start with a CT scan and THEN do an MRI next with abnormal results, and only with abnormal results a neurologist is called.
Now do I think, like you, that the MRI is better... yep. You may be required through insurance purposes to do a CT first and the doc knows this, or it may be an MD preference based on experience and standards of care.
Me, I'd definately call the MD, ask WHY not an MRI, and although it's easy for me to say, I'd personally have no problem with the sedation, but I'm unfairly familiar and comfortable with the safety. Your child will only be without you for the 5 minute head scan... and if you want, you can down on a ton of lead protective barrier and go into the scan too. My facility allowed it, but discouraged in your child bearing years.
After, you'll be in a recovery room with him and the RN that has your child as a 1:1 and you'll participate in keeping him stimulated and awake, he'll have to drink and be well awake before you can be discharged.
I hope everything turns out for the best for you