An MRI will show inflammation and soft tissue changes better than an x-ray or cat scan. An MRI is especially useful for people who do not have significant bone damage yet, because with MRI you can see the inflammation in the bone that cannot be seen with x-rays or cat scans.
However, in your case you already know that you have sacroiliitis, both from the recent cat scan and from the imaging you had at diagnosis. So you would need to ask your rheumatologist whether any information the MRI might provide would make any difference in the treatment he/she would prescribe.
Does your rheumatologist think the pain is from the SI joint or from the disc?
Ginny - 57 year old female
Dx with USpA in March 2013; changed to AS in July 2015
Iritis and Scleritis
unicompartmental knee replacement June 2014
MTX, Humira, Cyclobenzaprine, plus Celebrex as needed
Supplements: Folic Acid, Vitamin A, Vitamin D, Calcium, Fish Oil, Melatonin, Culturelle probiotic