PET scan (Positron Emission Tomography)

Description

A positron emission tomography (PET scan) is an imaging test that reveals how the tissues and organs are functioning. It uses a very small dose of radioactive chemical called radiotracer injected into a peripheral vein to show this activity.

Purpose of a PET Scan

PET scans are commonly used to:

• Diagnose Cancer: Detect cancerous cells and determine if cancer has spread (metastasized).
• Monitor Treatment: Evaluate the effectiveness of treatments like chemotherapy or radiation therapy.
• Assess Brain Disorders: Identify conditions such as Alzheimer’s disease, epilepsy, or brain tumors.
• Evaluate Heart Function: Detect areas of reduced blood flow or damage in the heart.

Indications for PET scan

• To detect cancer cells and to do initial staging and classification.
• To detect certain heart problems by identifying the areas of decreased blood flow.
• To detect brain disorders and central nervous system problems.
• For assessing the response to cancer treatment.
• To detect any cancer metastasis and/or recurrence.

Use of PET scan

The radioactive tracers administered as an intravenous injection is usually labelled with oxygen-15, Fluorine- 18, Carbon-11 or Nitrogen-13.
It is used to:

1. Measure the physiological functions, such as blood flow, oxygen consumption and glucose metabolism, in order to identify if the organs and tissues are functioning normally.
2. Investigate diseases, such as epilepsy, Alzheimer’s disease, cancer and heart disease.
3. Diagnose a disease condition or to track how it is developing.
4. Identify the areas of decreased blood flow in the heart to decide on angioplasty or bypass surgery.
5. Evaluate certain brain disorders by observing the blood flow and oxygen consumption in different areas of the brain as in brain tumors, strokes, dementia, Parkinson’s disease, etc.
6. Distinguish between benign and malignant tumors as malignant tumors metabolize glucose faster than benign tumors. Whole body scans are often performed to stage a cancer.

Patient preparation for the procedure

1. Explain to patient that the procedure will be performed in the radiology room in the scanner machine.
2. The test in the scanner may take about 35-40 minutes during which he/she will remain still so that the machine will take accurate pictures.
3. Inform that the procedure requires injection of a radioactive substance that emits positively charged particles.
4. Inform that the test will be painless and the patient will be fully clothed.
5. Reassure that radiation exposure is minimal.

Prior to the test

1. Refrain from strenuous activities, such as exercise for 24 to 48 hours preceding the test.
2. For 24 hours before the test, stick to a low carbohydrate and no sugar diet. Avoid cereals, pasta, rice, bread, milk, yogurt, fruits, alcohol and caffeinated beverages. Foods to include are nonstarchy vegetables, nuts, meat and fish.
3. Do not eat or drink anything for about 4-6 hours. Drink only sips of water to take medicines.
4. Remove any jewelry and wear hospital gown.
5. Follow doctor’s instructions, if diabetic or breast feeding.
6. Void before taking the isotope injection for starting the procedure.
7. After injection of the isotope, rest quietly on a stretcher for 15-20 minutes to allow the substance to circulate in the organs.

After the procedure

1. Can go about with normal activities unless the doctor gives other instructions.
2. Drink plenty of fluids to flush out the tracer from the body.
3. Limit contact with pregnant women and infants for 12 hours.

Risks related to PET scan

• Major allergic reactions in rare instances.
• Exposure of unborn baby to radiation if the woman is pregnant.
• Exposure of child to radiation, if breast feeding.

Special considerations

Before the Procedure

1. Patient Education:
   • Explain the purpose of the PET scan, which evaluates metabolic activity in tissues and organs.
   • Reassure the patient that the procedure is non-invasive and generally safe.
2. Dietary Restrictions:
   • Instruct the patient to avoid eating or drinking anything except water for 4–6 hours before the scan.
   • Recommend a low-carbohydrate diet for 24 hours prior to the procedure to optimize imaging results.
3. Medication Review:
   • Confirm the patient’s current medications and discuss any adjustments needed, especially for diabetic patients.
   • Diabetic patients should manage their blood sugar levels carefully and may need specific instructions regarding insulin or oral medications.
4. Pregnancy and Breastfeeding:
   • Verify if the patient is pregnant or breastfeeding, as the radioactive tracer may pose risks. Alternative imaging methods may be considered.
5. Clothing and Accessories:
   • Advise the patient to wear loose, comfortable clothing without metal components, such as zippers or buttons.
   • Remove jewelry, watches, or other metallic items that could interfere with the scan.

During the Procedure

1. Tracer Administration:
   • Administer the radioactive tracer intravenously and allow time for it to circulate (usually 30–60 minutes) before imaging begins.
   • Monitor the patient for any adverse reactions to the tracer.
2. Positioning:
   • Ensure the patient is positioned comfortably on the scanner table to minimize movement during the scan.
   • Provide pillows or supports as needed to maintain a relaxed posture.
3. Monitoring and Support:
   • Observe the patient for signs of discomfort or anxiety and provide reassurance.
   • Encourage the patient to remain still during the scan to avoid blurry images.

After the Procedure

1. Hydration:
   • Advise the patient to drink plenty of water to help flush the radioactive tracer from their body.
2. Post-Test Care:
   • Inform the patient that they can resume normal activities unless otherwise instructed.
   • Discuss any follow-up steps, such as when and how the results will be shared.
3. Radiation Safety:
   • Recommend avoiding close contact with pregnant women or young children for a few hours after the scan, as a precaution.

REFERENCES

1. Annamma Jacob, Rekha, Jhadav Sonali Tarachand: Clinical Nursing Procedures: The Art of Nursing Practice, 5th Edition, March 2023, Jaypee Publishers, ISBN-13: 978-9356961845 ISBN-10: 9356961840
2. Omayalachi CON, Manual of Nursing Procedures and Practice, Vol 1, 3 Edition 2023, Published by Wolters Kluwer’s, ISBN: 978-9393553294
3. Sandra Nettina, Lippincott Manual of Nursing Practice, 11th Edition, January 2019, Published by Wolters Kluwers, ISBN-13:978-9388313285
4. Adrianne Dill Linton, Medical-Surgical Nursing, 8th Edition, 2023, Elsevier Publications, ISBN: 978-0323826716
5. Donna Ignatavicius, Medical-Surgical Nursing: Concepts for Clinical Judgment and Collaborative Care, 11th Edition ,2024, Elsevier Publications, ISBN: 978-0323878265
6. Lewis’s Medical-Surgical Nursing, 12th Edition,2024, Elsevier Publications, ISBN: 978-0323789615
7. AACN Essentials of Critical Care Nursing, 5th Ed. Sarah. Delgado, 2023, Published by American Association of Critical-Care Nurses ISBN: 978-1264269884
8. Ernstmeyer K, Christman E, editors. Nursing Fundamentals [Internet]. 2nd edition. Eau Claire (WI): Chippewa Valley Technical College; 2024. PART IV, NURSING PROCESS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610818/

Stories are the threads that bind us; through them, we understand each other, grow, and heal.

JOHN NOORD

Connect with “Nurses Lab Editorial Team”

I hope you found this information helpful. Do you have any questions or comments? Kindly write in comments section. Subscribe the Blog with your email so you can stay updated on upcoming events and the latest articles.