PET CT

What is a PET CT?

A PET CT scan combines two powerful imaging tools:

Positron emission tomography (PET)
Computed tomography (CT)

Merging these technologies into one exam gives your doctor a more complete picture of what’s happening in your body. A PET CT can show not only the size and shape of your organs but also how well they’re working.

PET Scan vs CT Scan: What is the Difference?

CT scan

A CT scan uses X-rays and computer technology to create detailed cross-sectional images of your body. It helps doctors see the size, shape, and exact location of structures like bones, organs, and soft tissues.

PET scan

The PET scan shows areas of increased metabolic activity, meaning it can detect more active cells. A PET scan highlights areas of increased metabolic activity by using a small amount of radioactive tracer injected into your bloodstream. More active cells, such as cancer cells, absorb more of this tracer, making them easier to detect.

By combining both types of images, doctors can more accurately diagnose and monitor conditions than with either scan alone. For this reason, PET CT is often used in:

Cancer detection and monitoring
Heart disease to assess blood flow or tissue damage
Brain disorders, including epilepsy, Alzheimer’s disease, and some brain tumors

How PET CT Scans Work

Tracers

Before the scan, a small amount of radioactive tracer is injected into your vein. This tracer travels through your body and collects in areas that are more metabolically active. These areas often light up on the PET scan.

The most commonly used tracer is fluorodeoxyglucose (FDG), a form of sugar that cancer cells absorb more rapidly than healthy cells. However, it is essential to note that not all cancers respond to FDG. For example, prostate cancer often requires a PSMA-based tracer, so FDG may not provide accurate results in those cases. Your oncologist will choose the right tracer based on your specific condition.

Contrast dye

Sometimes, the CT scan includes contrast dye to help highlight certain tissues and blood vessels. This dye can be administered orally, through an IV, or both.

While many people tolerate contrast well, it’s important to let your doctor know if you:

Have kidney disease
Are allergic to iodine or contrast dye
Have had a reaction to contrast during a past imaging test

Preparing For Your Scan

Your doctor will give you specific instructions before your appointment, which can include:

Avoiding eating or drinking beverages other than water for at least 6 hours before your scan
Limiting physical activity for 24 hours beforehand, as exercise can affect your results
Wearing comfortable clothing without zippers or metal

PET CT Scan Steps

You’ll receive a small injection of radioactive tracer and wait about 30 to 60 minutes while the tracer moves through your body.
You’ll lie still on a scanning table as it slowly passes through the PET CT scanner. The scan itself usually takes 20 to 45 minutes and is painless.
After the scan, you can return to your usual activities. Drinking water can help flush the tracer from your system.

When Will I Get My Results?

A radiologist will review your images and write a report for your doctor. While the results are not immediate, in most cases, your doctor will contact you within a few days or let you know when to follow up.

PET CT Scan Cost

The cost of this scan varies depending on your location, insurance coverage, and the reason for the scan. Insurance may cover part or all of the cost. It is essential to contact your insurance company in advance to verify coverage and determine any necessary pre-approvals.

A PET CT scan is a powerful diagnostic tool. It gives your doctor essential information to plan your treatment with greater precision.

PET CT Scan FAQs

Will the radiation from a PET CT scan affect me long-term?

The amount of radiation used is small and considered safe for most people. The benefits of accurate diagnosis often outweigh any risks.
Can I still get a PET CT scan if I have high blood sugar?

Yes, but it’s important to keep your blood sugar under control before the scan. High blood sugar can affect how your body absorbs the tracer used in the scan, which might lead to unclear or inaccurate results. To help get the best images, your doctor may ask you to fast, eat fewer carbs, or adjust your medications before the test.
Can I drive myself home after the scan?

Yes. The scan doesn’t cause drowsiness or affect your ability to drive. Unless your doctor tells you otherwise, you can return to your normal routine afterward, including work or activities.