Why have a mri on bowels? i aalready had a ct and colonosby

Depends: Sometimes ct and colonoscopy cannot get you enough information in terms of differentiating tissues on scan or exam or to get a more detailed look. That is when an MRI is appropriate which may be the case with you.

Exact test protocol: Depends on what is being looked for. A standard abdominal and pelvic ct for abdominal pain and bloating is not optimized to look at small bowel. The colonoscopy is great for looking at the large bowel (colon) but only sees a small portion (if any) of the distal small bowel. Mri enterography is a special protocol that is excellent at looking at small bowel. Perhaps this explains your situation.