What is a scan | Diseases and conditions: Medical tests.

Scan

The scan is an imaging test - similar to x-rays, computed tomography, magnetic resonance imaging...-, which is very helpful to diagnose certain diseases, mainly some pathologies of the appliance endocrinological, bone, respiratory, and renal, although it can be used almost in any organ of the human body.
The interpretation of the test depends on the body that we want to study and also the suspected diagnosis that you have in mind. The test can be used to detect tumors, ensure the good functioning of a gland, identify failures of blood perfusion, checking the existence of active infections, etc.
The Administration of a radiopharmaceutical that designates the affected parts of the bodies that we want to study is required for its realization. A radiopharmaceutical is a molecule capable of attached to specific proteins and cells. The cells can be inflammatory (designated infection or immune processes), cancer (tumors detected), blood (draws the blood supply) or any other type. Each radiopharmaceutical therefore has a specific role and is different for each organ and suspected diagnosis.
This molecule is attached to a radioactive isotope that emits detectable energy by means of cameras sensitive to radiation. Therefore it is a technique that involves a previous preparation and subsequent care somewhat cumbersome, that makes that this is not done urgently, but it is used in patients or as out-patient study.
While it seems a very innovative practice, the scan is one of the first imaging techniques that have been used in medicine. So the experience in its interpretation is wide and there are a large number of studies on their safety. It is normal that the words 'radioactivity' or 'isotope' thinking that it is a dangerous test, however, the radiation is a natural source of energy and every day we are exposed to radioactive energy that comes from the rocks and soil, mainly. The dose of radioactivity has been much lower years and today the benefits of this test outweigh the risks.

When a scan is done

We can divide the indications of the scan according to the organs to study with her. In each one there are different uses of this test:

Bone scan:

· To detect bone tumors or Metastases of tumours of other organs of the body.
· Identify sources of infection (osteomyelitis, spondylodiscitis, etc.).
· Study of bone pain of unknown causes.
· Rating diseases of bone metabolism: osteoporosis, osteomalacia, Paget's disease, hyperparathyroidism...
· Identify bone fractures when routine radiographs are dubious and are not sufficient to diagnose them.

Renal scan:

• Global study of the kidneys when CT cannot be performed with radiocontrast by allergy or severe renal impairment.
• Signs of rejection in transplanted kidney.
• Identify possible kidney damage and scars on children who have reflux vesicoureteral (RVU), which predisposes to repeated infections.

Endocrine scan:

• Study of thyroid: is one of the most common uses of the scan.
  1. Detect thyroid nodules and guide if they are benign or malignant.
  2. Study the overall functioning of the thyroid gland, if it is hiperactivada or little working.
  3. Check the existence of goiter and what their activity.
• Study of adrenal glands:
  1. Complete study of the adrenal glands when the TAC was not enough.
  2. Identify a pheochromocytoma, a product derived from the adrenaline-producing tumor.
  3. Identify a neuroblastoma, a tumor that appears in children of congenital form.

Ventilation/perfusion scan:

• Evaluation of pulmonary thromboembolism, to check parts of the lungs that lack them blood flow while you get them properly air through the bronchi.
• Study perfusion isolation of specific regions of the body, to identify infection or ischemia.

Digestive scan:

• Detection of Meckel's Diverticulum, a malformation of the gastrointestinal tract that can produce very far from stomach ulcers in the wall of the small intestine.
• Study of digestive bleeding.
• Evaluation of the liver function and bile ducts associated for the diagnosis of congenital malformations.
• Identify rare intestinal tumors.

Heart scans:

• Identify very early episodes of ischemia with exercise.

Neurological scan:

• Research of nerve pathways of neurotransmitters in the brain.

Preparation for the scan

If you are performing a scan these are issues you must keep in mind to help you prepare for the test:
Duration: the test usually lasts two to three hours, since the administration of the radiopharmaceutical until you can leave the hospital.
Admission: admission is not needed, it can be done on an outpatient basis.
Is necessary to be accompanied?: not, is a painless and not invasive, so you can only attend the clinic and return in the same way.
Drugs: don't need to take any prior medication. You must tell your doctor all the medicines that you eat so that you assess whether to modify any or not.
Food: many times it is recommended to go on fasting to the scan. Ask your doctor when send you the test.
Clothing: is better to go with comfortable clothes at the hospital will be changed by a gown to make it easy to expose part of the body being studied.
Documents: before testing you will be asked to sign informed consent which will explain why it is necessary to perform the scan and the potential risks involved. You only need to carry the health insurance card and the wheel of the test the day you go to do it. Normally you will not you any report of results.
Pregnancy and breast-feeding: the scan is a test fully prohibited during pregnancy, since it implies an exposure to radioactivity. If there is minimal risk of being pregnant you should get a pregnancy test before to dismiss it (even women carrying the IUD should do it). Breastfeeding is also a contraindication for the scan, as 2-3 days after the test it is recommended not to keep close contact with small children, because they are more sensitive to radioactivity.
Contraindications: pregnancy, breastfeeding and allergy to the radiopharmaceutical are absolute contraindications. Other more relative contraindications according to each concrete with renal or hepatic insufficiency, and having another scan the two months prior to the test.

How is the scan

When you arrive at the clinic to make you a scan, they will call you that passes to a room of nursing where will be administered a radiopharmaceutical intravenously. To spend the radiopharmaceutical to the blood you may notice heat or cold, depends on the supplied molecule. The radiopharmaceutical will be different according to the organ and pathology to study (for example, for the thyroid is the iodine-131 and for infections 67 gallium). Sometimes the radiopharmaceutical may be given by mouth or inhaled form.
You have to wait an hour until the radiopharmaceutical begins to take effect and be able to track the area to study with the camera. Meanwhile, you can go to a dressing room where you will you change your clothes for a more comfortable gown and leave your personal belongings. Sometimes you don't need to wear a gown and you can spend with your street clothes and then you here the part of the body wanting to explore you. Sometimes also need to wait that long, it is necessary to track the camera minutes after the administration of the radiopharmaceutical and perform serial during the hour after images.
When you have passed an hour you will be taken to the room where the appliance that performs the scan, you'll see a table or Chair and beside a machine with an arm that can move and head towards the area of the body to study. You will be asked to lean on the table in a specific position according to the area who want to measure. If we study the thyroid you tumbarás you face up to capture the neck area. If you measure the kidneys you are sitting or lying down with an outdoor lumbar back area. Once settled you won't need to worry about anything else, just be relax and remain still.
The sanitary technician will handle the machine and begin measuring the radiation that emits the radiopharmaceutical when it is attached to the cells and proteins. Sometimes not only performs a fixed image of radiation, a video that see the radiopharmaceutical distribution through circulation can be blood or moving the organ to study. This is an important advantage over static such as x-ray or computed tomography Imaging tests.
Throughout this process you won't feel anything. A few minutes later the sanitary technician will tell you that the test has finished and you can already get up from the couch. You can also ask you to wait a few minutes in the waiting room to check that you don't have any dizziness or late adverse reaction to administration of the radiopharmaceutical.
After the test you won't feel anything unusual in the area in which that have measured the radioactivity. You can collect your things from the dressing room and leave the clinic in the same way that you've come. For the next 2-3 days is recommended to avoid contact with young children or people with Hematology, since you emitirás radioactivity that the days will decrease to disappear.

Complications of the scan

The complications of the scan are very similar to other imaging tests that require before administering a substance that allows to visualize organs (such as the intravenous contrast). The most frequent complication is the allergy to the radiopharmaceutical, usually mild allergic reactions and anaphylactic shock is very rare.
To be a test that uses radiation, there is an increased risk of developing tumors in the long run. It should take into account this fact to only put to the test when necessary, though the risk is minimal and the benefits are greater. Indeed, there are studies showing that reduced doses of radiation can reduce the risk to develop tumors, since they eliminate potentially malignant cells.
It is not necessary to use lead radiation shields in any case, since the radiopharmaceutical is delivered intravenously and also reach throughout the body.

Results of the scan

The results of the scan are obtained at the same time make it, but it is necessary a physician specializing in this type of evidence to interpret them. Doctor who is usually responsible for the scan is a nuclear medicine specialist, who oversees the test and analyses the results obtained writing a report that will give to the doctor who has commissioned the test (rheumatologist, pulmonologist, endocrinologist, etc).
The results will be interpreted very differently depending on the studied organ and the context of the patient. Some of the more frequent the scan results would be:

Bone scan:

· Tumors or metastases: it sees an increase in radiation in the form of more or less defined nodules.
· Infection: is an increased radiation diffuse areas that appears a few minutes after the administration of the radiopharmaceutical.

• Metabolic diseases: there are bone loss and the issuance of global radiation in osteoporosis or osteomalacia. Paget's disease is a bone metabolism, so it will appear areas with radiation increased in size and intensity.
• Fractures: sees an increase in radiation in recent fractures by active inflammation. If they are old fractures radiation may be less by focal bone mass decrease.

Renal scan:

• Chronic kidney disease: are the kidney areas that do not emit radiation by fibrosis.
• Vesicoureteral reflux: If there are scars are identified by a decrease in the radiation, sometimes in the form of star.

Endocrine scan:

• Study of thyroid:
  1. Hiperfuncionantes nodules: is focal increased radiation. They tend to be benign tumors.
  2. Hipocaptantes nodules: is focal decrease of radiation. They tend to be malignant tumors.
  3. Hyperthyroidism: increased global radiation. Typical of Graves disease.
  4. Hypothyroidism: overall decrease of radiation.
  5. Thyroiditis: absence of radiation on a global basis by destruction of the thyroid gland.
• Study of adrenal glands:
  1. Pheochromocytoma or neuroblastoma: increased focal radiation. Depending on the age of the patient and the used radiopharmaceutical is suspected one or another tumor.

Ventilation/perfusion scan:

• Pulmonary embolism: see decrease in the radiation of the areas little perfundidas with a normal ventilation radiation emission.

Digestive scan:

• Meckel's diverticulum: increased radiation located at a midpoint of the small intestine (near the navel).
• Digestive bleeding: is detected radiation of red blood cells marked within the digestive tract.
• Hepato-Biliary malformation: absence of radiation in the bile ducts.

Heart scans:

• Coronary ischemia: decrease of radiation in localized areas of the wall of the heart, are detected by performing moderate physical exercise.

Neurological scan:

• Research: the traces of radiation emission can be brain nerve pathways of specific molecules.

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