Pet Scan

Overview

A PET scan (positron emission tomography) is an imaging test that shows how your organs and tissues are working. Before the scan, you receive a tiny amount of a safe radioactive substance called a tracer. The tracer collects in areas of high activity, such as cancer cells or inflamed tissue, and the scanner picks up signals to create detailed pictures. It is often used to detect cancer, heart problems, or brain disorders, and to check how well treatment is working.

PET scans are a common diagnostic tool in hospitals and imaging centers worldwide. They are not used as a routine check-up but are done when a doctor needs specific information about how your body is working.

A PET scan may be recommended for people of any age who need detailed information about a known or suspected condition, such as cancer, heart disease, or certain brain disorders. It is also used in research.

Symptoms

Common symptoms

• There are no 'symptoms' of a PET scan itself. You may be referred for a PET scan if you have symptoms such as unexplained weight loss, persistent fatigue, or a suspicious lump.
• For cancer, symptoms may include pain, abnormal blood tests, or changes seen on other imaging tests like X-rays or CT scans.
• For heart conditions, symptoms might include chest pain or shortness of breath.
• For brain conditions, symptoms may include memory problems, confusion, or seizures.

Symptoms in children

• A child may need a PET scan to check how well treatment is working, often for conditions like lymphoma or other childhood cancers.
• Children may feel anxious about the scan; the medical team can explain it in a child-friendly way and may allow a parent nearby.
• Special care is taken to use the smallest amount of tracer needed for children.

Symptoms in older adults

• Older adults may undergo PET scans to evaluate cancer, assess heart damage, or investigate suspected dementia.
• Some older adults may have difficulty lying still or managing the fasting requirement; talk to the team if you need extra support.
• Kidney function may be checked before the scan, as the tracer can be affected by kidney problems.

Causes

Main causes

• Cancer – to detect tumors, see if cancer has spread, or check response to treatment.
• Heart disease – to measure blood flow to the heart muscle and identify areas with poor flow.
• Brain disorders – to help diagnose conditions like Alzheimer's disease or find seizure focus.
• Infection or inflammation – to locate areas of serious infection or chronic inflammation.

Risk factors

• There are no risk factors for having a PET scan. It is a test, not a condition.
• The main 'risk' of the scan is exposure to a small amount of radiation, which is considered safe for the information gained.
• If you are pregnant or breastfeeding, tell your doctor because special precautions may be needed.

When to see a doctor

See a doctor urgently if:

• If you were referred for a PET scan due to symptoms that are getting worse, such as increasing pain, cough, or unexplained bleeding, call your doctor promptly.
• If you developed a high fever or difficulty breathing shortly after the tracer injection, seek urgent medical help.

Book a routine appointment if:

• If you already have a scheduled PET scan, follow your doctor's instructions and attend the appointment.
• If you have not been referred but are worried about symptoms, book a routine appointment with your doctor to discuss them.

Diagnosis

A PET scan is not a diagnostic test in itself; it produces images that your doctor interprets. The scan is a procedure performed by trained radiographers in a hospital or imaging center.

Tests that may be done

• You will receive an injection of a small amount of radioactive tracer (a type of sugar).
• You will rest quietly for about 30 to 60 minutes while the tracer spreads through your body.
• You will lie on a flat table that slides through the scanner, which looks like a large doughnut.
• During the scan, you must lie still; the scan may take 20 to 40 minutes.
• A CT scan is often done at the same time to combine structural and functional images.

What to expect at your appointment

Before the scan, you will be given instructions about fasting. On arrival, you change into a gown, get an IV line placed, and receive the tracer. You may feel a brief cold sensation. After the scan, you can return to normal activities and drink plenty of fluids to flush the tracer out. Your doctor will receive the results within a few days.

Treatment

A PET scan is not a treatment – it is a diagnostic tool. The information from the scan can guide your treatment plan. Depending on the results, your doctor may recommend further tests, surgery, radiation therapy, chemotherapy for cancer, or medications for heart or brain conditions. Talk to your care team about what the scan shows and what it means for your individual situation.

Self-care at home

• Follow all pre-scan instructions, especially about fasting and avoiding caffeine.
• Tell the imaging team about any medicines you take, including over-the-counter drugs and supplements.
• Drink extra water after the scan to help your body clear the tracer.
• Bring someone to drive you home if you were given a sedative, though this is not usually needed.

Medical treatments

Treatment depends on the condition being evaluated. For example, if the PET scan shows cancer, options may include surgery, radiation, or chemotherapy. If it shows heart muscle damage, your doctor may discuss medications, angioplasty, or lifestyle changes. For brain conditions, medicines or supportive therapies might be offered. Your healthcare provider will explain the plan based on results.

When is surgery considered?

If the PET scan identifies a localized abnormality that is best removed, your specialist may recommend a surgical procedure. This will always be discussed with you in detail before any decision.

Living with this condition

Most people do not have lasting effects from a PET scan. The day of the scan, you may feel tired or have a mild headache from fasting. After that, you can return to your usual routine. If the scan is part of cancer treatment, you may have ongoing appointments and follow-up scans.

Lifestyle tips

• Stay physically active at a level that feels comfortable for you.
• Get enough rest, especially after the scan if you feel tired.
• Keep a follow-up appointment to discuss results.
• Keep a list of your medications and medical history to bring to appointments.

Diet and exercise

Drink plenty of water after the scan to help flush the tracer from your body. Unless your doctor says otherwise, you can resume your normal diet and exercise routine immediately after the scan.

Mental health and emotional wellbeing

Waiting for scan results can cause anxiety and worry. It is normal to feel stressed. Try to stay busy, talk to friends or family, and ask your healthcare team about counselling services if you need additional support.

Prevention

A PET scan is a diagnostic tool, not a medical condition, so it cannot be prevented or avoided. However, unnecessary exposure to radiation is avoided by only using this scan when it is truly needed. If you have cancer or another condition, the scan itself helps doctors prevent complications by treating the underlying illness early.

Vaccines

Vaccines are not related to PET scans. However, staying up to date on recommended vaccines helps prevent infections that could complicate your health condition.

Screening programmes

PET scans are not used as a routine screening test for healthy people. Your doctor will decide if a PET scan is appropriate based on your symptoms, prior tests, and medical history.

Complications

If left untreated

• If the condition being evaluated (such as cancer or heart disease) is left untreated, it may progress and cause worse outcomes. A PET scan helps avoid this by providing a clear picture earlier.
• False-positive or false-negative results can sometimes occur, which may cause distress or delay in diagnosis.
• Rarely, the tracer injection can cause a mild allergic reaction or a small bruise at the injection site.

Long-term outlook

The outlook for most conditions is much better when they are detected early and treated appropriately. A PET scan gives your healthcare team valuable information to improve your care. Even if the results show an abnormality, remember that many treatments are available and your medical team will guide you through the next steps with support.

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