Hi Nur,
MRI (Magnetic Resonance Imaging) is a pain less procedure. You just have to lie down still while the machine slides you in and scans your body using magnetic waves.
A FerriScan is basically also an MRI just that the scanned data is sent to FerriScan HQ where they interpret the Iron concentration from it.
(http://www.chipple.net/mt/archives/20050616mri.jpg)
Take care, Peace!