We get MRI's of patients spines who have Harrington Rods all the time. It is
safeSafe driving for teens
Safe sex and not a risk. The rod is made of stainless steel and in your case is likely completely stable in the fusion bone. It will not move, bend or break, nor heat up in an MRI. The rod can interfere with the image quality around the area of the rod (T5-L3) but the images below L3 -S1 should be fine.
Tell the MRI secretary to ask the radiologist rather than making the assessment herself. I am sure he will allow it to go ahead.
Sarita