MRI
1-Stands for magnetic resonance imaging.
2-Don't involve x-ray.
3-Use strong magnetic field and radio frequency signals.
4-Examin the tissues containing lipids and water due to the presence of protons.
Contrast agent used are those having paramagnetic properties.
5-Have much greater soft tissues contrast than CT.

CT
1-Stands for computer tomography
2-Use x-ray (ionizing radiation)
3-Examin tissues composed of elements having high atomic number than the surrounding areas such as bones or calcifications within the body.
4-Contrast agents used are elements having high atomic number such as iodine and barium.