PET-CT scan

What is PET/CT Imaging?

Positron Emission Tomography (PET) is a medical imaging test that combines two techniques: PET and Computed Tomography (CT), to provide detailed images of your body. PET imaging uses small amounts of radioactive materials called radiotracers, a special camera, and a computer to evaluate the functions of organs and tissues. By identifying changes at the cellular level, this imaging can detect the early onset of disease before it is visible in other imaging tests.

How PET Works?

PET is a type of nuclear medicine imaging. Nuclear medicine uses small amounts of radioactive materials called radiotracers. Doctors use nuclear medicine to diagnose, evaluate, and treat various diseases, including cancer, heart disease, gastrointestinal, endocrine, and neurological disorders, among others. Nuclear medicine scans reveal molecular activity, enabling them to detect diseases in their early stages and assess the response to treatment.

Non-Invasive Procedure

Nuclear medicine is non-invasive. Except for intravenous injection, it is typically painless. These tests use radioactive substances called radiopharmaceuticals or radiotracers to help diagnose and evaluate medical conditions. Radiotracers are molecules attached to small amounts of radioactive material that accumulate in tumors or areas of inflammation.

They can also bind to specific proteins in the body. The most common radiotracer is Fluorodeoxyglucose (FDG), a molecule similar to glucose. Cancer cells, being more metabolically active, may absorb glucose at a higher rate, which can be seen on PET scans. This allows your doctor to detect the disease before it is visible in other imaging tests. FDG is just one of many radiotracers either in use or under development.

Common Uses of PET

Doctors use PET scans for the following purposes:

• Detecting or diagnosing cancer.
• Determining if cancer has spread in the body.
• Evaluating the effectiveness of treatment.
• Assessing if cancer has returned after treatment.
• Evaluating prognosis.
• Assessing tissue metabolism and viability.
• Determining the effects of myocardial infarction on areas of the heart.
• Identifying areas of the heart muscle that could benefit from angioplasty or coronary artery bypass surgery (in combination with myocardial perfusion imaging).
• Evaluating brain abnormalities, such as tumors, memory disorders, seizures, and other central nervous system disorders.
• Mapping normal human brain and heart function.

Preparation for PET Imaging

To ensure accurate results, follow these instructions carefully. Here are some general guidelines:

• Fasting: You may be asked to fast for a specific period before the scan, usually 4 to 6 hours.
• Medications: Inform your doctor of all medications you are taking, including over-the-counter drugs, vitamins, and supplements. Some medications may interfere with the scan or require special preparation.
• Diabetes: If you have diabetes, you may need to adjust your insulin or oral medication before the scan.
• Clothing: Wear comfortable, loose-fitting clothes. Avoid wearing jewelry or clothing with metal zippers or snaps.

During the PET Scan

PET is a painless procedure that typically lasts between 60-120 minutes. Here’s what to expect during the scan:

• Injection: A small amount of radiotracer will be injected into your body, usually through a vein in your arm. The radiotracer helps highlight areas of your body being scanned.
• Absorption Time: After the injection, you will relax in a comfortable room to allow the radiotracer to distribute throughout your body. There are no side effects, and you are allowed to drink water and use the restroom if needed. This part takes about 45-60 minutes.
• Imaging: You will lie on a table that moves through the PET scanner, which captures images of your body. You need to stay still during the scan to ensure clear images. The scan itself can take between 20 to 45 minutes.
• Relaxation: You will be asked to relax and breathe normally during the scan.

Post-PET Scan

After the scan, you can resume normal activities unless advised otherwise by your doctor. It is important to drink plenty of fluids to help flush the radiotracer from your system. Here are some other things to keep in mind:

• Results: Your doctor will review the PET scan results and discuss them with you. Depending on the results, additional tests or treatments may be recommended.
• Radiation Exposure: PET scans involve exposure to a small amount of radiation. While the risk of harm is low, it is important to inform your doctor if you are pregnant or may be pregnant, as radiation can harm a developing fetus.

Advantages of PET Imaging

PET is the most accurate medical tool for identifying cancerous and non-cancerous tumors, helping to reduce the number of unnecessary procedures due to inaccurate staging information and diagnosis. For those concerned about infection from medical treatments, PET scans are the best available solutions. PET can be used as an alternative to biopsies and other exploratory surgeries to determine the extent of the disease, as it analyzes the patient’s metabolic activities. PET scans are more successful than traditional imaging tests because they can analyze biological functions through biochemical processes, allowing them to identify problems before symptoms and signs appear. PET scans are safer than other CT scans because they expose the patient to less radiation.

Disadvantages of PET Imaging

Although the radioactive materials used in these scans are temporary, they can still cause difficulties, especially for pregnant women. The sensitivity of this diagnostic technique is another issue with PET. The likelihood of false results from imaging increases if the patient has a chemical imbalance, such as diabetes, or has recently eaten before the procedure.