Summary of the article
What is a scintigraphy ?
The scintigraphy enables the visualization of changes in diseased tissue. It highlights the affected areas in the form of scintillating dots that correspond to the concentration of the radioactive product absorbed by the tissue.
Using a gamma camera placed in front of the organ to be studied and a radiopharmaceutical agent injected intravenously, a map of the fixation points of the product in the body is recorded, which makes it possible to define the so-called hyperfixation zones as well as the hypofixation zones.
Scintigraphy is used to explore all anatomical regions. It is used to diagnose infectious, traumatic or tumor lesions.
The principle of scintigraphy based on a gamma camera which detects the radiation emitted by the radioactive substance injected into the blood.
The tomoscintigraphy has the particularity of obtaining cross-sectional images thanks to a positron camera that rotates around the patient. It is mainly used to explore the skeleton, heart, brain and lungs.
How is a scintigraphy performed ?
It takes 2 to 4 hours to complete a scintigraphy. The preparation time is the longest step.
You will first be supported by a radiology technician who will inject the radioactive tracer into a vein.
This is followed by a waiting period that can vary from a few minutes to several hours, depending on the area to be examined. During this period, it is recommended that you drink a lot of water to accelerate the elimination of the product. You can go to the bathroom before the examination to empty your bladder.
The waiting period is necessary for the product to diffuse widely throughout the body and to attach itself properly to the tissues being analyzed. If the doctor authorizes it, you can wait outside the department and leave without any risk.
The last step is to record the radiation from the radiopharmaceutical agent using two sensitive sensors positioned near you. You will lie on the examination table and not move for 15 to 30 minutes.
At the end of the examination, the information collected will enable to target the areas where the radioactive isotope is more concentrated.
Preparing for a scintigraphy
In most cases, you do not need to fast, so you can eat and drink as usual. Depending on the scintigraphy, you may be asked to temporarily stop your medication. You will then follow carefully the instructions given by the medical staff.
On the day of the examination, please remember to present the following documents to the secretariat :
Your health insurance card ("carte vitale") and complementary health insurance card ("mutuelle")- Your prescription
- Your previous scintigraphy
- Your previous reports and images related to the condition which will allow a comparison and a better follow-up (X-ray, ultrasound, scanner, MRI...)
- Your blood test results.
Preferably wear clothes that do not have zippers or snaps, avoid wearing jewelry and hairpins, otherwise you will have to remove them.
Injection in nuclear medicine
Intravenous injection for scintigraphy is mandatory since the principle is based on the diffusion of a radiopharmaceutical agent in the body. This agent, injected in small doses, is not harmful to the patient and is well tolerated. Side effects are extremely rare.
The nature of the radiopharmaceutical product depends on the organ to be analyzed :
- The radiopharmaceutical used for bone scintigraphy is composed of bisphosphonates, coupled with radioactive technetium 99m
- Iodine 123 is used for the thyroid
- Thallium 201, analogous potassium for myocardial scintigraphy
- MIBI, DTPA, MAG3, DMSA, HIDA and technetium are all tracers regularly used for myocardial, renal, biliary, thyroid and salivary gland scintigraphy respectively.
- Octreoscan or MIBG to explore an organ (brain, heart, lungs, liver, kidneys, lymphatic vessels ...) or diseases (eg. certain cancers)
- FDG, a substance close to glucose, is the product most commonly used for PET scans (positron emission tomography) in the diagnosis of cancers
After the scintigraphy
At the end of the examination, the images will be interpreted by the specialist. He will communicate the results orally and you will receive a written report.
It is important to follow a few precautions when undergoing a scintigraphy :
- Avoid close (less than 1 meter) and prolonged (more than 30 minutes) contact with young children or pregnant women for hours after the exam
- Drink plenty of water (unless medically contraindicated) to facilitate the elimination of the injected product
- If you are hospitalized, report that you have had a scintigraphy in the days following the examination
- Bring a certificate indicating the radioactive element that was administered if you travel in the days following the examination (some airports and border control are equipped with radioactivity detectors)
What are the risks of a scintigraphy ?
The amount of injected radioactive substance is extremely small. In terms of irradiation, it does not represent a danger either for you or for those around you (because you are likely to deliver very low doses of radiation around you).
Regardless of the biological elimination, radioactivity decreases logarithmically with time. Thus irradiation is not greater than a chest X-ray or abdomen.
The risks and side effects associated with drug injection are extremely rare : see Injection in nuclear medicine.
A major contraindication is pregnancy, as for all examinations that expose to radiation. It is therefore imperative to report any possible or current pregnancy so that precautions can be taken.
Examination Categories in nuclear medicine
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Where to make the specialty : Nuclear scintigraphy
- Lausanne
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