PET-CT patient guide

Overview

A PET-CT scan is a type of imaging test that combines two different scans: a PET scan and a CT scan. The PET scan shows how your organs and tissues are working, and the CT scan shows the structure of your body. Together, they give your doctor detailed pictures to help find or monitor diseases like cancer, heart problems, and some brain disorders.

PET-CT scans are a common imaging test used in hospitals and imaging centers worldwide. They are not routine for everyone but are frequently used for cancer diagnosis, staging, and treatment planning.

PET-CT scans are usually done for people who may have cancer, heart disease, or certain brain conditions. They are also used to check how well a treatment is working.

Symptoms

Common symptoms

• No symptoms directly from the scan itself, but the test is often done when a person has symptoms like unexplained weight loss, persistent cough, lumps, or fatigue that may need further investigation.

Symptoms in children

• In children, a PET-CT scan may be used to diagnose or monitor childhood cancers or other conditions. The symptoms that lead to the scan depend on the specific condition.

Symptoms in older adults

• In older adults, the scan may be used for cancer, dementia, or heart problems. Symptoms that may lead to a scan include memory loss, chest pain, or abnormal lab results.

Causes

Main causes

• PET-CT scans are not caused by a condition – they are a test used to investigate many conditions. Common reasons for having a PET-CT scan include diagnosing cancer, seeing if cancer has spread, checking treatment response, evaluating heart muscle damage, and helping diagnose brain disorders.

Risk factors

• There are no risk factors for needing a PET-CT scan. However, the scan uses a small amount of radiation. While the risk from one scan is very low, you should tell your doctor if you are pregnant, might be pregnant, or are breastfeeding.

When to see a doctor

See a doctor urgently if:

• If you have symptoms that your doctor thinks require urgent investigation, such as new lumps, unexplained pain, or concerning changes in your health.

Book a routine appointment if:

• If your doctor recommends a PET-CT scan as part of a regular follow-up for a known condition, you can schedule it at your convenience.

Diagnosis

A PET-CT scan is itself a diagnostic test. It does not diagnose a single condition but provides images that help doctors find abnormalities. The final diagnosis is made by reviewing the scan results along with other tests, such as blood tests or biopsies.

Tests that may be done

• Blood tests before the scan to check blood sugar levels.
• Your doctor may ask you to avoid eating for 4-6 hours before the scan.
• You may have a CT scan or MRI before the PET-CT for comparison.

What to expect at your appointment

When you arrive for your PET-CT scan, a technologist will explain the process. You will be asked to change into a hospital gown and remove any metal objects. A small amount of radioactive tracer will be injected into a vein in your arm. You will then wait about 30-60 minutes for the tracer to spread through your body. During the scan, you lie on a table that slides into the machine. It is important to stay still. The machine may make buzzing or clicking sounds. The scan is painless. After the scan, you can resume normal activities. The tracer leaves your body naturally through urine over the next few hours.

Treatment

The results of a PET-CT scan help your doctor decide on the best treatment plan. Treatment depends on the condition found. For example, if cancer is detected, treatment may include surgery, radiation therapy, or other approaches. The scan itself is not a treatment.

Self-care at home

• Drink plenty of water after the scan to help flush the tracer out of your system.
• Avoid close contact with pregnant women, babies, and young children for several hours after the scan, as the tracer may be slightly radioactive.
• Follow any specific instructions given by your healthcare team.

Medical treatments

If the scan shows a condition, your doctor will discuss treatment options. These may include medication, radiation therapy, chemotherapy, or other targeted therapies. Your doctor will choose the approach based on your specific situation. Always ask your doctor about the benefits and risks of any treatment.

When is surgery considered?

If the scan shows a tumor or other abnormality that can be removed surgically, your doctor may recommend surgery. The decision depends on the type, size, and location of the abnormality, as well as your overall health.

Living with this condition

Having a PET-CT scan does not change your daily life. You can go back to your normal routine right after the scan. If the scan finds a condition, your life may change depending on that condition and its treatment.

Lifestyle tips

• After the scan, you can eat and drink normally unless told otherwise.
• You may drive yourself to and from the scan, but if you have had sedation, you will need someone to drive you.

Diet and exercise

For the scan itself, you may be asked to avoid food and drink (except water) for 4-6 hours beforehand. After the scan, a normal diet and exercise are fine. If you are being treated for a condition, your doctor will give specific advice on diet and exercise.

Mental health and emotional wellbeing

Waiting for scan results can be stressful. It is normal to feel anxious or worried. Talk to your doctor or a counsellor if you feel overwhelmed. If you are being treated for a serious condition, consider joining a support group.

Prevention

A PET-CT scan itself does not need prevention – it is a test. However, some conditions that require a PET-CT scan, like cancer, may be prevented or caught early by living a healthy lifestyle, not smoking, staying active, and having recommended screenings.

Vaccines

Some cancers can be prevented with vaccines, such as the HPV vaccine for cervical cancer. Ask your doctor about vaccines that may be right for you.

Screening programmes

Regular screening tests for cancer (mammograms, colonoscopies, etc.) can help find problems early, which may reduce the need for more advanced imaging like PET-CT.

Complications

If left untreated

• If the conditions that require a PET-CT scan are not treated, they can worsen. For example, untreated cancer may spread, or an infection may get worse.

Long-term outlook

Most people who have a PET-CT scan do so because their doctor suspects a health issue. The scan provides valuable information that can lead to early and effective treatment. With proper medical care, many conditions can be managed successfully. Your healthcare team will guide you through the next steps based on your results.

Find support

International organisations

• World Health Organization Cancer

Helplines

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