question: I just had an MRI a few weeks ago on my lower back and I finally just got my results and I was wondering if you could tell me what it means. It says the Central disc L4-L5 is noted as well, there is a slight narrowing of the thecal sac with AP dimension of 8.6 mm at this level, it was 9.8 on the prior exam. The impression states: from exam dated 9/10/2012, there have been large reabsorption of significant disc fragment at L5-S1, mild central disc herniation remain. There is mild central disc and 45 which is narrowing the AP dimension of thecal sac from prior examination. If you could please tell me what this means that would be great and thank you for your time.