MRI vs CT Scan

One of the common questions about MRI vs CT scan asked by patients is what is the difference between CT and MRI ? Why should i have a CT instead of an MRI ? Or why should i have an MRI instead of a CT ?

These are very common questions , the answer come from 2 other very important questions

What part of the body does your doctor want to see ? AND

what is the reason for the exam ?

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.

The are also reason why CT is the exam of choice over MRI. It is the preferred modality for cancer, pneumonia, and abnormal chest X-ray. 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 have 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 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 whiche test is best for showing anatomy according to the reason for the exam. Very experienced CT and MRI technologists will aso know from working with Radiologists.

The difference between MRI and CT scans

MRI is Magnetic Resonance Imaging and a CT is a Computed Tomography

CT scanner uses X-rays , a type of ionizing radiation, to acquire its images, making it a good tool for examining tissue composed of elements of a relatively higher atomic number than tissue surrounding them, such as bone and calcifications within the body or of structures (vessels, bowel ).

MRI , on the other hand , uses non-ionizing radio frequency signals to acquire its images and is best suited for non-calcified tissue.

CT may be enhanced by use of contrast agents containing elements of a higher atomic number than surrounding flesh(iodine , barium ).

Contrast agents for MRI are those which have paramagnetic properties. One example is gadolinium .

MRI can generate cross-sectional images in any plane including oblique planes.

CT was limited to acquiring images in the axial or near axial plane in the past. The scans used to be called Computed Axial Tomography scans.

However, the development of multi-detector CT scanner to produce data that can be retrospectively reconstructed in any plan with minimal loss of image quality.

For purposes of tumor detection and identification, MRI is generally superior.However , CT usually is more widely available, faster, much less expensive, and may be less likely to require the person to be sedated or anesthetized.

MRI is problematic in case if the patient is having some metallic implant, which will cause interference with the magnetic field.