MRI question. Dist?

Hi Everyone!

Quick question, obviously I know none of you are here in a medically qualified capacity but I wondered if anyone knows what dist 6mm means printed on my MRI images? It says thk 5mm, which seems to mean the slices are 5mm thick (is that decent?) but I can’t find an explanation of the dist thing (6.3mm on some, 6mm on others).
Anyone know from your own experiences?
Thank you!

Sorry - I haven’t a clue