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PET Scan: It’s Uses & Procedure

Raina Rahul Agarwal 19 Jun, 2022 Medical Devices 1 Comment
PET Scan

What Is A PET Scan

The full form of PET Scan is Positron Emission Tomography. It is an imaginary test and helps to reveal the metabolic and biochemical function of human tissue and organ. It is a combination of nuclear medicine and biochemical analysis. This test uses a safe injectable radioactive chemical called a radiotracer and its device called a PET scanner A PET scan is an effective test to identify the condition of many diseases like cancer, heart disease and brain disorder. It helps to check the biochemical stage of these diseases.

PET scanner
A PET scanner is a large machine with a round, donut-shaped hole in the middle.

 The main function of the PET is to evaluate the metabolism of a particular organ and tissue. With the help of this procedure anatomy and physiology and biochemical properties of the organ or tissue are evaluated.

How Does PET Work?

PET scan is a nuclear medicine procedure. In this procedure, a tiny amount of a radioactive substance i.e radiopharmaceutical (ribonucleotide or radioactive tracer) is used during the examination of the tissue under study. A radionuclide is a combination of chemical substances and radioactive atoms. It is made by attaching radioactive atoms and chemical substances used naturally by the particular tissue or organ during the metabolic process.

For PET scanning a health worker also uses a scanning device (a machine with a large hole at its centre). This device detects the photon emitted by a radionuclide. Diseased cells in the human body absorb more tracer or radionuclide than a healthy person. A PET scan detects this radiation and produces images of the affected tissue.

What Are The Uses Of PET scans in health department:

PET scan is useful in the following disease:
Cancer: Breast Cancer, Lung Cancer & Thyroid Cancer, Prostate Cancer, Pancreatic Cancer, cervical, Colorectal Cancer, Esophageal Cancer, and Head & Neck Cancer.

Heart Disease: Coronary Artery Disease, Congestive Heart Failure, Pulmonary embolism & Pulmonary Sarcoidosis,

Brain Disorder: Brain tumours, Epilepsy, Dementia, & Alzheimer’s disease, Parkinson’s disease, Seizures, Stroke, Tumor, Multiple Sclerosis, Huntington’s disease.

Why a PET scan Is Used?

PET scan is used to evaluate the condition of organs and tissue of the human body for the presence of disease. It is also used to evaluate the function of organs such as the heart or brain. Cancer is the most common disease and health providers evaluate and diagnose it with the help of a PET scan.

There are some common diseases:

Cancer: A PET scan is useful for cancer as it can scan the entire body and pinpoint both. It can scan the primary stage and area of metastasis (Where cancer has spread). Cancer cells have more metabolic rate than noncancerous cells. Hence cancer cells often show up as bright spots on PET scans due to this high chemical activity of cells.

Therefore PET scan is useful for detecting cancer and checking whether cancer has spread or not, seeing if the chemotherapy is working or not, and checking for a cancer recurrence.

Heart Disease: In some conditions, blood flow decreases when someone suffers from heart, lungs and brain disorders. In that case, a PET scan is able to identify that area where blood flow decreases. Because healthy heart tissue is able to absorb more tracer while non-healthy heart tissue is not able to absorb. The different colour and brightness levels of the scan indicate different levels of cell function.

Brain: As glucose is the main fuel of the brain PET scan tends to measure the level of glucose. The brain uses glucose for metabolism. In a PET scan of the brain, its tracers (radioactive atoms)absorb glucose and create a radionuclide called Fluorodeoxyglucose (FDG). PET scan can detect the area of radioactive glucose where the brain is using a high rate of glucose. In a simple way, we can say that a PET scan measures brain activity in relation to areas of high and low radioactivity.

What Is The Procedure Of the PET scanner?

PET scan follows these procedures:

  1. At first, the patient will be asked to remove the clothing, Jewellery and other objects and the patient will be asked to wear a gown which will be provided by them.
  2. Now they will be asked to empty the bladder before the examination.
  3. Then one or two intravenous (IV) will be started in the hand or arm for injection of radionuclide.
  4. Some types of abdominal or pelvic scans require a urinary catheter to be inserted into the bladder to empty the urine during the procedure.
  5. There are such conditions where an initial scanner is also needed prior to the injection of the radionuclide. In this scan, the patient will be positioned on a padded table inside the scanner.
  6. After that radionuclide will be injected into an IV. It will be allowed to concentrate in the organ or tissue for about 30-60 minutes.
  7. After the absorption of the radionuclide for fix time scan will start. The scanner will move slowly over the body part being examined.
  8. After the completion of the scan, the IV will be removed from the hand or arm. If a urinary catheter has been inserted it will also be removed.

Frequently Asked Question

Que: What does a PET scan reveal?
Ans: A PET scan reveals the physiologically, anatomy and chemical function of the tissue or organ that is studied.

Que: How long does the PET scan procedure take?
Ans: A PET scan can take approx 30-90 minutes.

Que: What care has to be taken after the PET scan procedure?
Ans: After the PET scan procedure a patient needs to take plenty of water to flush out the radioactive tracer.

Que: Why does the patient have to take a rest before a PET scan?
Ans: Any type of physical activity can affect the result of the PET scan and leads to a false positive.

Que: What are the disadvantages of PET scans?
Ans: A PET scan sometimes cannot show accurate results when it is slow-growing and less active tumours. In that case, it may not absorb much tracer so it is unable to identify cancer.

Conclusion: PET scan is widely used in Oncology, neurology and cardiology. However current PET scans have some limitations such as long scanning times, low signal-to-noise ratios and high dose of ionizing radiation. Long-range, full-body PET provides a solution to these problems and greatly improves system sensivity.

Disclaimer: All the content of this article is for information purposes only.



author avatar
Raina Rahul Agarwal
A Non-Medical Scientist, BSL-2 Lab, Mirzapur

Raina Rahul Agarwal

A Non-Medical Scientist, BSL-2 Lab, Mirzapur

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