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Is my CAT a type of PET?

Posted on Apr. 17, 2019 ( comments)
Spine MRI horizontal

Has your doctor ordered additional tests to help diagnose your medical condition? Today's advances in technology and medicine have revolutionized how we discover and treat disease, but confusing abbreviations abound.

PET? MRI? CT? Keep reading to learn more about the "ABCs" of medical imaging.

A hundred years of X-ray technology

Most of us have probably had an X-ray or two at some point in our lives, perhaps at the dentist or to detect a broken bone. X-rays were discovered by a German scientist back in 1895 and are still commonly used today to take pictures of inside the human body.

X-rays are a type of invisible light called electromagnetic radiation that readily passes through the body to reveal skeletal structures and surrounding tissues.

Advanced X-rays for greater clarity and precision

CT or CAT scans, or computed (axial) tomography, use a combination of X-rays and computers to provide an internal 3D "snapshot." A CT scanner rotates around the body to capture a cross section of the body's organs, blood vessels and soft tissues.

This type of imaging may be required if your medical practitioner needs more details beyond the two-dimensional picture provided by a traditional X-ray.

A PET scan — an abbreviation for positron emission tomography — is another type of imaging that uses X-ray technology in the detection and diagnosis of certain conditions such as heart disease and cancer.

During a PET scan, the patient receives an injection of a particular radioactive dye that is clearly viewed as it is absorbed into the body. The images provide highly detailed pictures of how specific organs and tissues are working or the location of diseases. 

MRI explained

MRI, or magnetic resonance imaging, does not involve X-rays. Instead, this imaging technique uses magnets and radio waves. MRI can gather more accurate information about different types of soft tissues and internal organs than X-ray imaging.

For example, MRI is often used to examine and evaluate the condition of blood vessels, muscles or the brain.

How is an ultrasound different from other types of scans?

Like MRI, ultrasound is another imaging technique that does not involve radiation. High-frequency sound waves create pictures of internal structures, such as soft tissue areas that don't show up as well with conventional X-rays.

Ultrasound is commonly used for a variety of medical purposes, such as maternity care and abdominal pain.


A mammogram is a low-dose X-ray that can detect breast cancer. Using two plates to compress the breast, images are taken from two different angles.

A newer type of mammography, 3D mammography (also called breast tomosynthesis), may allow doctors to see breast tissue more clearly and reduce the chance for the patient to need additional exams. The breast is compressed, as in a traditional mammogram, but many low-dose X-rays are taken to create a three-dimensional picture.

DEXA scans

Dual energy bone densitometry, also called DXA or DEXA imaging, is another type of X-ray imaging that measures your bone mineral density.

Bones that are not very dense are usually brittle and weak. DXA is commonly used to diagnose osteoporosis or other conditions that may cause a loss in bone density in both adults and children. These scans track the effectiveness of treatments and help assess your risk for developing bone fragility or loss. 

New advances in imaging at MultiCare

MultiCare will soon offer a 3T MRI at MultiCare Tacoma General Hospital as well as the Axumin PET scan at MultiCare Allenmore Hospital.

Tacoma General's 3T MRI uses a stronger magnet than conventional MRI to reveal even greater detail and superior-quality images. This allows clinicians to perform exceptionally detailed imaging studies to benefit the region's neurology and urology patients.

Unlike conventional bone scans, the revolutionary Axumin PET scan can show recurrent prostate cancer at a much earlier stage, as well as pinpoint the new growth's exact location. This increased level of detection is a powerful diagnostic tool to help clinicians direct more effective therapy for men with prostate cancer. 

Learn more about medical imaging at MultiCare

Posted in: General Vitals

About The Author

Jean Hanavan Kelly
Freelance writer Jean Hanavan Kelly has a Master of Science in Health Communications and a background in promoting health literacy to help people navigate our ever-changing, increasingly complex health care environment. More stories by this author
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