Radio frequency ablation can be life changing for people that have SI joint pain. And if you are seeing a little bit of improvement from your injection, your doctor may be heading in that direction.

I have an autoimmune disease that has been messing with my back for many years. I've had two lumbar spine surgeries in the past and in 2018, my left SI joint was fused. My disease is progressive and has become much more active in the past couple of years.

Low back and SI joint pain is tough. I have had 17 MRIs on my low back and pelvis. There are times when a scan shows only osteoarthritis because I'm not particularly inflamed that day. Less so now that I'm in an active disease state.

I recommend that if you are regularly taking anti inflammatory drugs, stop taking them for a couple of weeks before a scan. Only if your doctors feel this is safe for you to do.

I know that for me personally, letting myself get inflamed pre-scan has been quite helpful. It's miserable because my immune system goes crazy when I'm not suppressing it but it's worth it in order to get a diagnosis and better treatment options.

Not sure if this helps you but hopefully it will at least give you some ideas.