CT Scan vs MRI Scan – What’s the Difference?

CT scan vs MRI scan – both are diagnostic medical tests that, like traditional X-rays, produce multiple images or pictures of the inside of your child’s body. Radiologists use the images generated from these scans to detect, diagnosis, or monitor your child’s health during and after treatment. So, what’s the differences between a CT (computerized tomography) scan and an MRI (magnetic resonance imaging)?

CT Scan vs MRI Scan – Knowing the Difference

While both scans provide diagnostic imaging, they capture these images very differently. The biggest difference between CT scans and MRI scans is that MRI scans use radio waves while CT scans use X-rays. There are a few other key differences between these scans which may make one a better option than the other for your child depending upon his medical circumstances. So, let’s take a closer look at each.

What is a CT Scan?

A CT scan also called a CAT scan, uses X-ray technology to take multiple images from different angles of the body area being examined. A special computer program processes the information from these images to create two-dimensional cross-sectional images. A computer monitor then displays the images for the doctor to read. Special software can create three-dimensional (3-D) images when requested by your child’s physician or the radiologist interpreting the exam.

A great way to visualize the process is to envision that you are looking at a loaf of sliced bread. Now think about what a slice of that bread would look like if you pulled it out of the loaf. What you’d see is the entire surface of that slice – from the outer edge of the crust to the center and across to the other outer crust edge. Just like slices of bread, CT scan images or “slices” show the body in the same kind of way. Each “slice” shows an image from the outer skin to the center part of the body. A CT scan exam produces multiple images or “slices” providing many different views. Computer software reassembles the images creating a very detailed multidimensional view.

CT images of internal organs, bones, soft tissue and blood vessels provide greater detail than traditional X-rays, particularly of soft tissues and blood vessels. CT scans are well suited for imaging injuries from trauma, staging cancer, and diagnosing conditions in blood vessels.

What to Expect During Your Child’s CT Exam

Your child will lie on a table that moves through the machine’s “doughnut hole” shaped scanner. Your child may hear soft whirring and buzzing sounds as the CT table moves back and forth through the machine taking pictures. The procedure may include a dye called contrast to help provided more information. The technologist may give your child the contrast to drink, or a nurse may put it in through an intravenous (IV) line. The CT scan takes about 5 to 15 minutes. It’s very important that your child stay still so that the pictures come out clear. He may need sedation or a general anesthetic if he is unable to stay still or hold his breath for the scan.

What’s an MRI Exam?

While the imaging machines may look the same, MRI scans do not work the same way as CT scans do. Instead of using ionizing radiation, MRI use radio waves and powerful magnets linked to a computer. MRI scans create very clear and detailed cross-sectional images of the body. Like slices of bread, each image shows a thin slice of the body. The MRI allows the physician to see many different “slices” of the area of your child’s body being examined.

MRI scans are great for looking at soft tissue, tendons, ligaments, your spinal cord and your brain. The pictures can show the difference between normal and diseased tissue.

What to Expect During Your Child’s MRI Exam

Most MRI machines are large, tube-shaped magnets which look like a doughnut standing up. Your child will lie still on a table that travels through the tube. During the exam, the machine is really loud and makes thumping noises and rhythmic beats. Your child may want to wear earplugs or headphones to help block out the noise. He may need to have a dye called contrast to help provided more information about his body. The technologist may give him the contrast to drink, or a nurse may put it in through an intravenous (IV) line.

If your child is uncomfortable in closed spaces, ask the doctor if he can have the exam in an open MRI machine. An MRI exam usually consists of several sequences, each lasting 2 – 15 minutes. He will be able to move slightly between sequences. However, during the exam, it is very important that he remain still so that the images are clear. Your child may need sedation or a general anesthetic if he is claustrophobic, unable to stay still or hold his breath for the scan.

Hungry for more information? Check out the National Cancer Institute’s “Children with Cancer – A Guide for Parents” which offers a wealth of helpful information. Or visit the American Childhood Cancer Organization.

As always, check back with us frequently and read our blog posts for more tips and information.

This information is of a general nature only and is not intended as a substitute for medical advice. If you have any questions or concerns, please ask your doctor or medical imaging staff.