After 6 long years of struggling w/severe SIJ pain, one SI joint injection, 4 RFA's, and endless MRI's of my LUMBAR spine, I finally got aggressively involved in my treatment and pushed for an MRI study of the sacrum. I have been told over and over, "this is not needed...there are never any findings, the lumbar MRI shows the sacrum, blah, blah, blah". A rheumatologist ordered an x-ray of my SI joints. This reflected problems and all I got from my PM doctor was yet another slip for a lumbar MRI. I called the rheumatologist and asked her if this was the test she really needed to have done. She said "no, no, no... I need an MRI of your sacral plexus". I had asked another dr for this 6 years ago. I recently had this done and it showed sacroilitis (inflammation, edema in the bone) and it has resulted in the need to rule out several types of non-rheumatoid inflammatory arthritis. With one of these two types, the pain always begins in the SI joints and an MRI that reflects sacroilitis is one of the diagnostic criteria. So I will be having a full rheumatology work-up. As I read the posts on SI joint pain I can see the same familiar things said to patients about the lack of need for scans of the sacrum. Unless the patient had an accident in which it was clear that the SI joints were injured, this scan should always be done and I would insist on it. And, by the way, my lumbar scan, which I had done at the same time came back "normal". So, no, a lumbar MRI does not show the sacrum in sufficient detail if your problem is SI joint pain.