PSMA PET Scan

What is a PSMA PET scan?

A PSMA PET scan is a type of imaging test that helps healthcare providers detect prostate cancer. It uses a radioactive tracer (radiotracer) to target the prostate-specific membrane antigen (PSMA) that prostate cancer cells make.

Imaging tests can be intimidating. But a PSMA PET scan is safe. You’ll feel a slight pinch when a provider uses a needle to put the radiotracer in your body. Otherwise, the scan mostly requires you to stay as still as possible to ensure clear images.

What does a PSMA PET scan stand for?

PSMA stands for prostate-specific membrane antigen. PSMA is a protein on the outside of prostate cancer cells. PSMA is also an antigen. Antigens are substances that cause your immune system to respond. They include:

• Bacteria
• Viruses
• Allergens
• Tumor cells

They even include normal cells.

PET stands for positron emission tomography. The scanner detects diseased cells that absorb large amounts of the radiotracer. This indicates a potential problem.

Is a PSMA PET scan a full-body scan?

Yes, a PSMA PET scan evaluates your entire body.

When is a PSMA PET scan performed?

A healthcare provider may recommend a PSMA PET scan if you receive a prostate cancer diagnosis and, during cancer staging (using the Gleason score), they identify that the cancer is at risk of spreading to other parts of your body (metastasizing) before you start prostate cancer treatment.

They may also recommend a PSMA PET scan if you’ve been treated for prostate cancer but later develop elevated prostate-specific antigen (PSA) levels. Elevated PSA levels may be a sign that prostate cancer has returned (recurrence).

Can a PSMA PET scan detect other cancers?

Healthcare providers typically use a PSMA PET scan to detect prostate cancer. But sometimes, PSMA isn’t “prostate specific.” In rare cases, other types of cancer can make low levels PSMA, which may show up on a PSMA PET scan. These types may include cancers that affect your:

• Salivary glands
• Thyroid
• Liver
• Kidneys
• Brain
• Breasts
• Lungs

How does a PSMA PET scan work?

A PSMA PET scan is a type of nuclear medicine imaging. It uses a small, safe amount of radioactive material to locate PSMA. A healthcare provider will give you the radiotracer through a peripheral IV into your bloodstream.

The radiotracer attaches (binds) to prostate cancer cells. The PET scan then detects the radiotracer and creates images of the affected areas of your prostate or other areas of your body where prostate cancer may have spread.

Providers may also use a PSMA PET scan along with a CT scan and/or MRI to help produce more detailed images of your body.

What should I expect before a PSMA PET scan?

Before a PSMA PET scan, a healthcare provider will review your medical history and perform a physical examination. A PSMA PET scan involves a needle to inject the radiotracer and a short, tunnel-shaped scanner. Let the provider know if you’re afraid of needles (trypanophobia) or enclosed spaces (claustrophobia). They can recommend coping strategies or give you a mild sedative to make yourself as comfortable as possible during the scan.

There are no special instructions that you need to follow to prepare for a PSMA PET scan. Unlike other types of imaging tests, you don’t need to stop eating or drinking (fast) or stop taking your medications. But it’s a good idea to wear comfortable clothes and leave any metal accessories at home, including jewelry and eyeglasses.

What should I expect during a PSMA PET scan?

You can expect the following during a PSMA PET scan:

• A healthcare provider who specializes in PSMA PET scans (PSMA PET scan technologist) uses a small needle to inject a standard PSMA dosage into a vein, usually in your arm. The most common radiotracers are Gallium-68 PSMA 11 (68Ga-PSMA-11) or piflufolastat F-18 (18F-DCFPyL or PyL).
• You’ll wait about an hour for the PSMA to travel through your body.
• The technologist will ask you to use the restroom to pee.
• You’ll lie on an exam table that slides in and out of the PET scanner. The scanner looks like a short tunnel or doughnut. It’s important that you remain as still as possible during the scan. Any movement can make the images blurry.
• The scanner will make buzzing and clicking sounds as it takes images of your body.

Before you leave, the technologist will review the images to make sure they aren’t blurry or out of focus.

How long does a PSMA PET scan take?

A PSMA PET scan usually takes less than two hours. It takes about an hour for your body to absorb the radiotracer, and the PSMA PET scan itself takes about 30 minutes. The technologist will also take time to review the images to ensure they’re clear.

What should I expect after a PSMA PET scan?

After the PSMA PET scan, you can go home. In most cases, a healthcare provider will contact you with your results within a few days.

What are the risks of a PSMA PET scan?

For most people, a PSMA PET scan is safe. But some people experience temporary side effects, including:

• Feeling very tired (fatigue)
• Headache
• Changes to your sense of taste (dysgeusia)
• Mild allergic reaction

What type of results do you get?

A radiologist with specialized training in PSMA PET scans will review the images. In any area with high levels of PSMA, the radiotracer will bind to the PSMA and light it up in the image. It’s like adding spot colors to black-and-white images.

What does PSMA positive mean?

A PSMA positive result means healthcare providers found PSMA in your PSMA PET scan. A provider may recommend more testing to make an official prostate cancer diagnosis or to make sure the positive test result is correct.

What level PSA can PSMA PET scan detect?

In people who have an early recurrence of prostate cancer, a PSMA PET scan can detect PSA as low as 0.2 or 0.3 nanograms per milliliter (ng/mL). A nanogram is one-billionth of a gram, and a milliliter is 1/1,000 of a liter.

With a PSA level of about 0.5 ng/ML, there’s about a 50% chance of finding a mass of about 5 millimeters (mm) in size.

When should I know the results of a PSMA PET scan?

A healthcare provider should contact you with your PSMA PET scan results within a few days.

If the results are abnormal, what are the next steps?

If healthcare providers detect PSMA in your PSMA PET scan, they’ll use the Gleason score and cancer staging to determine how serious the prostate cancer is and the types of treatments you need. Your treatment may vary according to several factors, including:

• Your overall health
• If the cancer has spread to other areas of your body
• How quickly the cancer is spreading

When should I call a healthcare provider?

Reach out to your healthcare provider if it takes longer than expected to get your PSMA PET scan results. If your results are positive, schedule regular follow-up appointments with your providers.

Is a PSMA PET scan better than an MRI?

A PSMA PET scan isn’t better or worse than an MRI. Both tests serve specific functions to help healthcare providers diagnose and monitor prostate cancer. A PSMA PET scan helps locate PSMA in your body. But an MRI can help them look at the shape of your organs or assess unhealthy tissue.

What is a PSMA PET/CT scan?

A PSMA PET/CT scan combines a PSMA PET scan with a CT scan. A CT scan is another type of imaging test that creates dozens or even hundreds of images to generate three-dimensional (3D) renderings of structures in your body. It helps healthcare providers detect certain types of cancers and tumors.