This is what they call a nonspecific finding on an MRI. That is, your history, physical examination, and symptoms and other studies like lab work all go into a diagnosis. They could have nothing to do with your complaint and could be an unrelated important or unimportant finding. One thing a pocket of fluid could be is an abscess, but there are other possibilities also. You will just have to wait to hear from the doctor who ordered the study to see what he says.
Thanks you so much...this helps me understand the MRI a lot.