Welcome to the board. I will try to give you some general information regarding the MRI report so you will have a better idea of the meaning of the terminology when you go back to see your doctor. Keep in mind that imaging is just one piece of the puzzle, and will be correlated with the results of a physical and basic neurologic exam as well as your description of your symptoms to arrive at a diagnosis.
Are you having some pain radiating down into the buttock and/or leg? Your report indicates a stenosis, which often results in nerve compression that causes that type of pain.
Stenosis commonly occurs in two places: one is the central canal which is part of the nerve center for the whole body and carries messages back and forth to the brain. The other spot is in the neuro foramina.
Located between every pair of vertebræ are two openings called the intervertebral foramina. These openings provide passage for the spinal nerve root, as well as a spinal artery, some veins, sinu-vertebral nerves and transforaminal ligaments. When these openings get closed up due to things that do not belong there such as bony overgrowths (bone spurs), swollen tissue, bulging discs or disc fragments, etc. there is competition for the space needed by the nerves to pass freely. The result is that the nerve ends up getting "squished" (my best medical terminology
) which results in pain that can radiate out to the limbs.
You will note that you have this issue, which is defined as MILD, in both locations at the L4-L5 segment, and in the foramen at L5-S1...but the central canal appears open at this level. (In "radiology-speak" how "bad" something is will be catagorized as follows: minimal, mild, moderate and severe. Mild stenosis indicates that there is some present, but it isn't a lot and may not be causing much of a problem.)
Next we'll tackle facet arthropathy (which is, again, described as mild). The facet joints are synovial joints that are what allow the spine to bend and twist. There are two facet joints in each spinal motion segment. They are subject to arthritic changes just as is the knee, finger, thumb, hip, etc. These joints show signs of degenerative changes from wear and tear in all of us as we use our bodies and age. As the cartilage begins to dry up and break down, the body's nature response is to grow new bony tissue in an attempt to stabilize the joint and replace what is being lost. Unfortunately it tends to grow into bone spurs, which can hang over into those foramen and cause stenosis.
You will note that at L4-L5, this facet arthropathy is described as moderate. There is also a small bulge in the annulus (which is the tough outer rim of the disc).
At L5-S1 the disc is in worse shape. The disc is the spongy cushion between each pair of vertebrae that is compromised mostly of water. As we age it tends to dry out and lose its height. This is what is meant by dessication and dehydration of the disc...and again, it is a sign of some degenerative change going on in this spinal segment. At this level the disc has a small protrusion where the bulge is pointing towards the middle part of the spinal canal. (as opposed to being off to the right or left side). This often means that there can be pain anywhere along the whole affected nerve.
I think I have covered the issues that are affecting these two levels. Luckily most of the issues are described as mild so there is a very good chance that your doctor will be able to prescribe conservative treatments that will help to resolve your pain without you needing surgical intervention.
Good luck and let us know how you are doing.
(By the way, there are some excellent drawings of lumbar anatomy available on line that will help you to understand how these facets, discs and vertebrae fit together and work in connection to one another.)