What does this mean?

I went to pick up a copy of my MRI today so I can take it to the neurologist on Monday. When I got the copy home, I had to look at it just to see what my spine looks like and found a note in with the films. It was a letter to my regular doctor stating the findings on the MRI. I'm doing some digging online to see what some of these words mean, but here is what was said:

At L4-5, disc desiccation is present Huh? What is desiccation? I looked online and this is what I've found so far.

This means "atrophy" or "drying out" of the intervertebral disc, resulting in loss of height. Spinal discs are normally rubbery round pads that are filled with a jelly-like substance called the nucleus. Normal disks are well hydrated, the nucleus containing 80 to 85% water and the anulus about 80%. Together with the cartilaginous end plates of the adjacent vertebral bodies, the intervertebral disk forms a disk complex that gives structural integrity to the interspace and cushions the mechanical forces applied to the spine. Dessication is often considered the first stage of spinal degenerative changes, and no longer provides the cushioning necessary between vertebrae.

Ok, so that would explain why I'm half an inch shorter now then I was when I was younger.

Metallic artifact at this level creates limitation of evaluation of patency of the canal Ok, I know what metallic artifact is. I have two steel rods in my back along with several pins and screws from my scoliosis surgery. But what is "Patency of the canal"?

Looks like this is talking about the narrowing of the spinal canal. Apparantly, the metal is making it too hard for the doctor to tell if there is any narrowing of the spinal canal here. Patent means the pathways are clear. I hope mine are.

And finally:

The canal and neuroforamina are patent at L5-S-1 Again, this looks to have something to do with the narrowing of the spinal canal. The neuroforamina is the neural opening. Again, patent means open so I guess this mean that the neural opening is clear and there isn't anything bulging into that space? Now I'm more confused then ever. The only thing I figured out for sure was that first paragraph about the disc desiccation. Everything else is still a muddled mess in my head. Guess I'll just wait and see if the neurologist can explain it better to me in simple English.