MRI vs. CT
CT Scan does not show you tendons and ligaments very well at all; at least not yet. MRI is the best choice for that. Tendons and ligaments around the shoulder and knee are best seen by the physics used in MRI. This is due to the density of the tissues that compose the tendons and ligaments.
Spinal cord is best seen by MRI for the same reason. The density of the spinal cord and the composition of it is such that MRI physics can show it to us much better than CT.
There are also reasons why CT is the exam of choice over MRI. It is the preferred modality for cancer, pneumonia, and abnormal chest x-rays. Bleeding in the brain, especially from injury, is better seen on CT than MRI. But a tumor in the brain is better seen on MRI.
If you've been in an accident, organs can get torn or damaged. CT shows organ tear and organ injury quickly and efficiently. Broken bones and vertebral bodies of the spine are better seen on CT but injury to the spinal cord itself is displayed on MRI far better than CT.
CT is far superior at visualizing the lungs and organs in the chest cavity between the lungs. MRI is not a good tool for visualizing the chest or lungs at all.
MRI vs CT scan depends on what needs to be visualized and the reason you need the test. Radiologists are the doctors that specialize in reading images of the body and therefore know which test is best for showing anatomy according to the reason for the exam. Very experienced CT and MRI technologists will also know from working with Radiologists.
The difference in the way the images are produced in MRI vs CT is the physics involved. CT scan uses an x-ray beam that slices through you like a knife carving a spiral ham.
MRI ( magnetic resonance imaging) uses a magnetic field with radio frequencies introduced into it. When your body is placed inside the magnetic field, the molecules of water in your body (hydrogen molecules) will start to spin like a kid's top when he spins it. The top will begin to wobble as it slows down.
Your hydrogen molecules will start to wobble just like the top does at a certain rate of speed; the stronger the magnetic field, the faster they will wobble and the weaker the magnetic field, the slower they will wobble; it depends on the strength of the magnetic field.
Then a radio frequency is introduced into the magnetic field at the same rate of speed at which the "tops wobble" causing the wobbling tops and radio frequency to sing out together sharing the same signal frequency. (Thus the term resonance) That signal is used by the MRI computer to produce the image.