What is a PET CT Scan?

CT scan or Computed Tomography Scan is an advanced radio diagnostic modality. This shows detailed pictures of the organs and the tissues inside our body. A PET (Positron emission tomography) scan can find abnormal activity and it can be more sensitive than other imaging tests aiding in detection of diseased cells. It may also show structure alteration / changes to our body sooner than occurrence of symptoms. Doctors use PET-CT scans to provide more information about the cancer.

PET CT scan detects early signs of cancer, heart disease and brain disorders. An injectable radioactive tracer detects diseased cells. A combination PET CT scan produces 3D images for a more accurate disease diagnosis.

Does one need additional blood tests and other scans to determine cancer?

PET CT scan results are usually used with other imaging modalities and laboratory test results. Other blood tests are required to find out whether an area that collected a lot of radioactive material is non-cancerous (benign) or cancerous (malignant). Expert doctors use co-relation of various blood tests and the PET CT Scan results in order to determine the type and extent of disease.

Does a positive PET CT scan mean cancer?

When you look at a PET CT Scan result plates, the Cancer cells show up as bright spots on PET scans. This happens due to the higher metabolic rate as compared to the normal cells. Modern day advanced PET CT scanners have a higher resolution limit of 4 mm, corresponding to the detection of tumors with a volume of 0.2 ml (7 mm diameter) which usually ensures elaborate and dependable results.

Does a patient emit radiation after a PET CT scan?

Although the scan involves injecting a radioactive substance into the patient’s body, which surely does lead to radiation exposure of persons in his/her vicinity. However, the amount of radiation coming from the patient following the scan is low. We recommend that infants, young children & pregnant ladies try and keep away for about 24hours till the radioactive material is excreted from the patient’s body.

Does PET CT scan show benign (non-cancerous) tumors?

A PET CT Scan aids in diagnosing cancer and gives a detailed information, including whether a tumor is benign (non-cancerous) or malignant (cancerous), whether the cancer cells are active or dead, and how well the cancer is responding to treatment offered.

Frequently Asked Questions about PET CT Scan

Positron Emission Tomography and Computed Tomography (PET/CT) gives you the combined information on anatomy, i.e. size and location of a tumour or mass along with metabolic functions like cellular activity of a tumour or mass, into an easily readable image.

To diagnose it accurately, doctors recommend this PET CT Scan . It will further help to stage and cure cancer, diagnose Alzheimer’s disease and even heart diseases. Some common doubts pop up in mind before taking up this scan. So, in this blog, we will answer all your queries in a layman language.

What is PET?

PET is an acronym for Positron Emission Tomography. PET uses radiation or nuclear medicine imaging to produce 3-dimensional colour images of the functional processes within the human body.

A Computed Tomography (CT) scan shows the structure. Merging these two scans into one highly sophisticated PET/CT imaging technique provides detailed information about the presence or spread of disease and accurately identifies its precise location

How does PET work?

It is a process of injecting a radiotracer (Radioactive glucose (sugar)) into the veins of the arm of the patient. The tracer will travel through the body and get absorbed by the organs and tissues which are to be studied. Then through high-tech machines, the energy given off by the tracer is converted into 3-D pictures.

How is a PET scan different from a CT or MRI scan?

To know about the energy changes at a cellular level, a PET scan is used. It also detects small cancers, differentiates between benign and malignant tumours, and also allows accurate staging. On the other hand, CT or MRI will detect structural organ or tissue changes that grow at a later stage.

How long does the test take?

It does not take more than 1 hour for the radiotracer to travel down your body and get absorbed into the organs or tissues after it is injected into the veins for examination. The scan lasts for about 20-45 minutes, and the patient has to remain still during the length of the examination.

You will have to sit or lie down on a bed for 30 to 90 minutes. The CT scan is completed first, followed by the PET portion. While performing the PET CT scan, you may be asked to hold your breath for some seconds.

Any preparation before a PET scan ?

The patient is not advised to eat or drink 6 hours before the scan. Even oral diabetic medications and Insulin should not be taken within 4 hours of the scan. Before the injecting radioactive glucose into your veins, blood glucose level should be less than 200. If it is above 200, then you must contact the PET facility before going for the scan.

Do not perform any strenuous or vigorous activity (e.g. aerobics, jogging, golf, etc.) for at least 24 hours before the scan. If you are feeling any anxiety or claustrophobia, you can consult it with your doctor and ask someone to drive you home. Wear comfortable clothes as the process will last for 2-3 hours.

What happens after the PET scan?

Try to intake as much fluid as you can after the scan is completed. If you are facing any side effects, immediately consult your doctor.

Informing prior to the scan

If you are pregnant, allergic to any food or drug, currently being treated for an infection, or had any recent radiation therapy, you must inform it to the staff before taking the test.

What will happen on the day of the appointment?

• Registration: The office personnel will note down your details and take you to the imaging area where our doctors will ask you some questions about medical history
• Blood Sample: To check your blood sugar level/glucose level, a small blood sample will be taken.
• Drink: The staff will give you a drink that you can see in the CT scan too! It will help the radiologist to observe your stomach and intestines on the CT images. In this way, they can distinguish them from other structures in your abdomen.
• Tracer Injection: The doctor will inject a small amount of radiotracer in your veins through an intravenous (IV) line.
• Relax: You will be asked to relax for an hour.
• The Scan: You will be asked to lie on a “scanning bed” and then scanning will take place for 20-25 minutes. It is advised that you do not move or adjust your position during the scan.
• Report: You will get the report within 24 hours.