What’s the Difference Between an Ultrasound, PET Scan, and MRI?

When doctors need an in-depth look of the body, they will refer their patients to get some type of diagnostic imaging. Different kinds of diagnostic imaging give different information about the body part being studied or treated. Each requires unique technological equipment, but all of them are non-invasive and painless. These types of tests help diagnose or rule out certain medical complications.


An ultrasound scan is used for diagnosis, treatment and for guidance relating to procedures such as biopsies. Doctors can use the ultrasound to determine whether a lump is a cancerous tumor or a fluid-filled cyst. It is also used on pregnant women and to detect problems in the liver, heart, kidney, or abdomen.

How it works:

The ultrasound works by using high-frequency sound waves to create images called sonograms. The ultrasound catches images when there is an echo or bouncing back of the organs. For example, the ultrasound will travel through blood in the heart chamber, but the image will show when the echo of the heart is received. 

PET Scan

A positron emission tomography (or PET scan) is mainly used in cancer treatment, neurology, and cardiology. Combined with an MRI scan, a PET scan can produce multidimensional images showing the inside of the human body. 

How it works: 

The PET scan works by using radiation to show activity within the body on a cellular level. During a PET scan, a machine detects radiation emitted by a radioactive material that is injected to the body, called the radiotracer. The radiotracer travels to the cells of the body and the activity of the cells will show on the screen as hot or cold spots. Compared to normal cells, cancer cells are very active and will show up on the screen as areas of cancer. 


The magnetic resonance imaging scan (or MRI scan) is one of the most common diagnostic imaging techniques around the world. It is used to create detailed images of the organs and tissues in the body. Doctors use MRI for several things: to check on tumors and cysts, injuries in the joints, diseases in the liver and abdominal organs, breast cancer screening, or anomalies of the brain or spinal cord. 

How it works:

An MRI scan uses a large magnet, radio waves, and a computer to create a detailed, cross-sectional image of internal organs and structures. It does not use harmful ionizing radiation. During the scan, the patient must stay still until it is over. 

Each of these diagnostic imaging scans have a specific purpose. If you have had a serious injury, or feel a very strong pain, it is important to check with a specialist. No matter which scan your doctor suggests, Windsor Imaging can help. For more information about our services, please visit our website.

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