You need a new MRI place!  Here, if you're not early enough register/change and actually to meet your table time (and shocker, they lie by a whole hour since people are always slow and late), you're rescheduled for another day/time.  I had a complete spine MRI and they scheduled me for 2.5 hours of table time -- I was done in 1.5 as they didn't have to redo any sequences, the techs were excited to get to go home before closing time.  I BSed with them for some time about the new equipment they're getting, and yes they can do MRIs up to 550lbs but they said the images are such garbage there's no good reason to do them.