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Whole-body scintigraphy or whole-body scan (PCI) is an imaging test ordered by a physician to investigate tumor location, disease progression, and metastases. For this, radioactive substances are used, called radiopharmaceuticals, such as iodine-131, octreotide or gallium-67, depending on the purpose of the scintigraphy, which are administered and absorbed by the organs, emitting radiation that is detected by the equipment. Find out what radioactive iodine is for.
Images are obtained through a device that tracks the entire body, after one or two days of substance administration. Thus, it is possible to verify how the radiopharmaceutical is distributed in the body.The test result is said to be normal when the substance is distributed uniformly in the body, and it is indicative of disease when a high concentration of radiopharmaceuticals is perceived in an organ or region of the body.
When is indicated
Whole body scintigraphy aims to investigate the primary site of a tumor, its evolution and whether or not there is metastasis. The radiopharmaceutical used depends on which system or organ is intended to be evaluated:
- PCI with iodine-131: has the thyroid as its main objective, especially in those who have already had their thyroid removed;
- PCI with gallium-67: is usually done to check the evolution of lymphomas, search for metastasis and investigate infections;
- PCI with octreotide: is performed to evaluate tumor processes of neuroendocrine origin, such as thyroid and pancreas tumors and pheochromocytoma.
Whole body scintigraphy is performed under medical supervision and does not pose a risk to the patient, as the administered radioactive substances are naturally eliminated from the body.
How PCI is made
The full body search is basically done in four steps:
- Preparation of the radioactive substance in the dose to be administered;
- Administration of the dose to the patient, either orally or directly into the vein;
- Obtaining the image, through the reading made by the equipment;
- Image processing.
Whole body scintigraphy does not normally require the patient to fast, but there are some recommendations to be followed depending on the substance that will be administered.
In the case of iodine-131, it is recommended to avoid foods rich in iodine, such as fish and milk, in addition to suspending the use of some medications, such as vitamin supplements and thyroid hormones before performing the exam.If a thyroid scan is not performed, but a thyroid scan only, fasting for at least 2 hours should be performed. See how thyroid scintigraphy is performed.
The exam is performed with the patient lying on his back and lasts about 30 to 40 minutes. In PCI with iodine-131 and with gallium-67, images are performed 48 hours after administration of the radiopharmaceutical, but if an infection is suspected, PCI with gallium-67 should be performed between 4 and 6 hours after administration of the substance. On the other hand, in PCI with octreotide, the images are taken twice, once with about 6 hours and the other with 24 hours of substance administration.
After the examination, the person can return to normal activities and should drink plenty of water to help eliminate the radioactive substance faster.
Care before the exam
Before undergoing whole-body scintigraphy, it is important that the person tell the doctor if they have any type of allergy, if they are using any medication that contains Bismuth, such as Peptulan, for example, which is used for gastritis, or if you are pregnant or breastfeeding, as this type of test is not recommended as it can affect the baby.
The side effects related to the administration of radiopharmaceuticals are rare, even because very low doses are used, but allergic reactions, skin rash or swelling in the region where the substance was administered may occur. That's why it's important for the doctor to know about the patient's condition.