Hello Mary and welcome to you and sweet Bodie. One in four diabetic cats has acromegaly, according to the most recent research, so you are in good company.

Brodie is on still a relatively small dosage of insulin. That research I mentioned said the average in their test group was 7 units BID, but we have some acrokitties on much larger doses. My Neko got up to 8.75 units. As far as dosing, a cat needs as much insulin as he needs. If Brodie's not in good blood sugar numbers, increase the dose. The acro tumour can pulse up and down, so you will find his dose needs change over time. Which is why it's good you are home testing. You want to get his numbers under renal threshold as much as possible, to reduce the impact on his kidneys.
A lot of people with acros find that Levemir is a better insulin, because it is a bit longer lasting. Lantus can sting at higher doses.
First a question for you, what does the vet hope to achieve with a MRI? With the IGF number you've got, I don't think you need any further diagnostics, especailly since you are seeing some visible signs. If you were to do radiation, a CT scan is typically the first step for planning the radiation. They would do an MRI if the CT scan doesn't show enough.
As for treatments, there are a few in the US (I am in Canada so similar options). First, the gold standard treatment is hypophysectomy, or surgical removal of the pituitary. The surgery is done in a very limited number of places - Washington State U being one. There isn't much expertise in that surgery in North America but a lot in London at the Royal Veterinary Clinic (RVC) which is at the forefront of acromegaly research. I have heard of people flying their cats to London from elsewhere in Europe, but it's a long trip. The treatment that you'll most commonly seen done here to date is SRT, or stereotactic radiation therapy. That's what Neko had done at CSU or Colorado State University. There are a number of other places in North America, and growing, that do that radiation. Petcure Oncology (Milwaukee) might be your closest options. Cyperknife is a slightly more advanced type of radiation treatment, but done in fewer locations.
There are a couple of medical options, cabergoline is a new mostly experimental approach that has been quite successful in a few kitties. Pasireotide is a more successful medical approach, but rather more expensive. Other than that, the vast majority of people with acrocats don't do treatments, and rather just treat with however much insulin they need. Until the very recent cabergoline trials, most of the treatment options have been rather pricey and radiation/surgery involves travel for most. Having said that, the field of treatment for acromegalic cats has changed a lot in the last few years. But it also means most vets aren't on top of the latest treatments. Heck, a lot of vets still think it's a rare condition they'll never see!