How Does a PET/CT Scan Work?


You probably heard of a PET/CT scan, but it can be challenging to understand what it is and how it works. “PET” stands for positron emission tomography and “CT” stands for computed tomography. A PET/CT scan allows doctors to visualize internal organs and tissue of the body. Doctors can order this scan to check different parts of your body. For example, cardiologists will order a PET/CT scan to understand how a heart attack affects the heart. These scans help to make a diagnosis and evaluate the prognosis of different conditions, making them a key tool to helping you stay on top of your health.

Learn more about how PET/CT scans work and what you can expect during your appointment.

How a PET/CT Scan Works

A PET/CT scan is a combination of two different scans. The scans can be done separately, but a PET/CT scan is usually done using a machine capable of performing both scans simultaneously. 

Before your PET scan, a nurse or technician injects a radioactive tracer into your body. This tracer helps doctors identify diseased tissue from healthy tissue, so they can quickly pinpoint problem areas. The radiation from this injection doesn’t stay in your body permanently and only remains for a short period while you receive your PET/CT scan.

Once in your body, the tracer will gather in areas that show signs of disease, like inflamed areas or areas with tumors. Areas of concern will appear denser on the images than healthy tissue and structures to make it easy for doctors to identify any problems.

For a CT scan, there is no requirement for a radioactive tracer. Instead, you receive an injection or consume a contrast dye so doctors can see problem areas more clearly. The dye will leave your body entirely within a day. When you get the CT scan, the machine uses x-rays to create three-dimensional images of your internal anatomy, including organs and blood vessels. This precise imaging helps doctors get a clear look at your body to make an accurate diagnosis.

A PET/CT scan creates a fusion of the two different types of images, allowing for a more in-depth view that can be used for diagnosis and treatment planning.

PET/CT Scans as a Screening Tool

What is a PET/CT scan used for? This noninvasive technology has several different applications. It can help detect various cancers, brain disorders, and heart conditions, often in the very early stages. Many types of doctors order PET/CT scans, including cardiologists, oncologists and neurologists. 

A PET/CT scan is a valuable screening tool to detect potential health issues before they progress to more serious and difficult-to-treat stages. This type of scan gives your doctor a lot of information, including measuring your vital functions and images of your body’s internal organs and tissues. Your cardiologist, for example, can use a PET/CT scan to determine if your arteries are constricted, affecting blood flow to your heart, and determine how much damage has been done by any previous heart attacks. Armed with this information, your healthcare team can make recommendations for treatment to help you live a healthy life.

What to Expect During a PET/CT Scan

A PET/CT scan is a non-invasive outpatient test. Your doctor will provide you with instructions and answer any questions you have about the scan. You may be asked to follow a special diet and avoid exercising for 12 to 24 hours before the scan. Once you arrive for your test, a nurse or technician will have you take the tracer and dye for your scan. You may receive both through an IV line, but you can receive the contrast dye in drinkable form instead. 

Once the tracer and dye travel throughout your body, you’re ready to get your PET/CT scan.

So, how long does a PET/CT scan take? This is usually one of the first questions people ask when they know they need to schedule a scan. The exact length of the scan will depend on what images your doctor will want to see, but the entire test typically takes about one to three hours. You will lay flat on your back on a table that will slide into the scanning machine, which looks like a large circle. The technologist in charge of the scanning process may move the table into various positions during the test to capture images from different angles.

How Your Doctor Uses the Images

  • Diagnose coronary artery disease: Coronary artery disease (CAD), a common heart disease, happens when plaque builds up in the walls of your arteries and blocks the necessary flow of blood to your heart. This type of blockage can cause a heart attack. Your doctor can see these types of blockages on the images produced by a PET/CT. 
  • Detect scar tissue and heart damage: Scar tissue can make it difficult for the heart to pump. The tissue damaged during a heart attack can become scar tissue, increasing the risk of further heart-related complications. 

After your test, you will have a follow-up appointment with your doctor to discuss the findings and next steps. 

The Fastest Scans in the Region

PET/CT scans can be done on different types of equipment. 128-slice CT scanning is a system designed to provide faster, more accurate imaging. During a PET/CT scan, the technician may ask you to hold your breath to ensure an accurate, clear image is taken. This request may be repeated multiple times throughout the procedure. The 128-slice CT scanning is faster than standard CT equipment, which reduces the need for patients to hold their breath during the procedure. 

The speed of the 128-slice system can take images so quickly that it can be used on patients who may typically need to take beta-blockers to slow their heart rate for the procedure. Modern Heart and Vascular is the only cardiology provider in the area with this type of system, making us a good fit for patients with rapid heart rates and arrhythmia. 

Prioritizing Preventative Care

Preventative care and early detection are vital for taking care of your health. At Modern Heart and Vascular, we focus on proactively monitoring your heart health. With early intervention, you often have more options for less invasive treatments. Take control of your health and learn more about how preventative care can help you get ahead of cardiovascular disease. If your doctor has told you it is time for a cardiac PET/CT scan, we are here to help you in Humble, Katy, and Cleveland, Texas. Reach out to request an appointment today.

This article does not provide medical advice. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. If you need cardiovascular care, please call us at 832-644-8930.

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