Tis finished. Praise the Lord it didn’t hurt (I didn’t know how they would have me lie down). Not a pleasant experience, but definitely worth the effort if we can get a solid diagnosis on my back.
from the Wikipedia page:
MRI works by making certain atoms in the body emit radiowaves by using a powerful magnet. When a person is in the scanner some of the hydrogen atoms, which are mainly found in water, align with this magnetic field. A radiowave at just the right frequency makes these atoms resonate and absorb energy. The atoms then release this energy in the form of a very weak radiowave that can be amplified and measured by the scanner. Extra magnetic fields are used to constantly change the magnetic field to allow images of the body to be reconstructed. These fields are created by gradient coils which make the familiar banging sounds of an MRI scan. Contrast agents may be injected to demonstrate blood vessels or inflammation in the tissues. Unlike CT scanning MRI uses no ionizing radiation and is generally a very safe procedure. Patients with some metal implants and cardiac pacemakers are prevented from having an MRI due to effect of the powerful magnetic field.