CT scan vs MRI scan
CT is the abbreviation of Computed Tomography. In CT scan X-ray beams are used to take image films. The X rays are high energy rays not visible to eye. When X-ray passes, it may be obstructed by tissues. The bone will resist the X ray most. So in the film the bony parts or calcified parts will appear as White. Depending on the amount of X-ray which passed through, the computer program will calculate and reconstruct the image of the tissue. The amount of X-ray which used in CT scan is much higher and it may cause the side effects. If CT is repeatedly taken, it may cause cancer. The CT scan gives the axial view of the tissue. So the films are usually two dimensional. Now there are three dimensional film reconstruction facilities available in CT also.
MRI is the abbreviation of Magnetic Resonance Image. It uses magnetic waves (which are not harmful like X rays). The MRI machine is similar to the CT machine in external appearance. However the mechanism is totally different. MRI scan gives better images than CT about the soft tissues. Brain and spinal cord images are better with MRI scan. MRI scan can be used in pregnancy as this is safe. CT is not advisable to take during pregnancy as it has radiation. MRI three dimensional pictures are used as MRI angiogram (study about the blood vessels)
Compared with the CT, MRI need more time. The patient needs to be inside the tube of the machine for a longer time. So the people who have fear about closed rooms, (claustrophobia) may face difficulties in MRI scan. CT can be taken on unconscious patient. But MRI needs patient’s cooperation to take a good film. Plain CT does not need any special preparation but MRI needs preparation. The metal clips (Tooth clips) and metal parts should be removed before MRI scan. The patient with previous surgery and metal clips used inside the body cannot take MRI scan, as the metal substances will be pulled out by magnetic field created in the machine. MRI cost more than CT.
In summary, CT and MRI are imaging techniques to film the tissue. CT uses x-ray which may be harmful, but MRI is safer. CT needs less preparation and bony parts can be seen clearly. MRI needs time for preparation and good for soft tissue image. MRI gives better 3 dimensional reconstructed views than CT. MRI is safer in pregnancy, CT not. The metal free environment is needed for MRI, but CT does not need those.