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Nuclear medicine

Nuclear medicine procedures (also referred to as scans, examinations, or tests) are safe, painless and cost-effective techniques that help diagnose medical problems in patients.

Nuclear Medicine tests are performed by introducing very small quantities of short-acting radio-isotopes by IV injection, oral administration, or inhalation. These isotopes are labelled with pharmaceutical agents that decay quickly but allow enough time to take pictures of your body or its organs (see example above) to help diagnose disease. The amount of radiopharmaceutical is kept at a minimum amount to reduce radiation exposure to a very low level to the patient and yet ensure an accurate test result.

Nuclear Medicine imaging is unique because it provides doctors with information about both structure and function of your body and its organs. It is a way to gather medical information that would not otherwise be available, and would have required surgery or other expensive diagnostic tests instead, since they often identify problems and abnormalities very early in a disease process long before they show up on other diagnostic tests.

Nuclear medicine differs from an x-ray, ultrasound or other diagnostic test because it determines the presence of disease based on biological changes rather than changes in anatomy. A special scanner (PET, SPECT or a Gamma Camera) is used to take these pictures of the body or organs which provides information that is subsequently used by your doctors.

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Brain scans are used to investigate problems within the brain and/or in the blood circulation to the brain.

Numerous imaging techniques have been developed and applied to evaluate brain hemodynamics. Among these are positron emission tomography, single photon emission computed tomography, Xenon-enhanced computed tomography, dynamic perfusion computed tomography, MRI dynamic susceptibility contrast, arterial spin labeling, and Doppler ultrasound. These techniques give similar information about brain hemodynamics in the form of parameters such as cerebral blood flow or cerebral blood volume. All of them are used to characterize the same types of pathological conditions. However, each technique has its own advantages and drawbacks.

courtesty of ahajournals.org

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Bone Scans can find bone cancer or determine whether a cancer from another area, such as the breast, lung, kidney, thyroid gland, or prostate gland, has spread (metastasized) to the bone.

A bone scan is a nuclear scanning test that identifies new areas of bone growth or breakdown. It can be done to evaluate damage to the bones, find cancer that has spread (metastasized) to the bones, and monitor conditions that can affect the bones (including infection and trauma). A bone scan can often find a problem days to months earlier than a regular X-ray test.

For a bone scan, a radioactive tracer substance is injected into a vein in the arm. The tracer then travels through the bloodstream and into the bones. This process may take several hours. A special camera (gamma) takes pictures of the tracer in the bones. This helps show cell activity and function in the bones. Areas that absorb little or no amount of tracer appear as dark or “cold” spots, which may indicate a lack of blood supply to the bone (bone infarction) or the presence of certain types of cancer. Areas of rapid bone growth or repair absorb increased amounts of the tracer and show up as bright or “hot” spots in the pictures. Hot spots may indicate problems such as arthritis, the presence of a tumor, a fracture, or an infection.

(courtesy of WebMD.org)

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HIDA (Hepatobiliary Scan) – for gallbladder

  • Used to evaluate gallbladder function, abnormalities within the gallbladder and check for gallbladder disease.
  • Assess abdominal pain, loss of appetite, nausea and vomiting, abnormal weight loss, check for gallstones

Liver Spleen Scan

  • This test is used to study the function and health of your liver and spleen and to check for any abnormalities or diseases within the liver or spleen.
  • Assess jaundice, liver cirrhosis or hepatitis, check for tumors on the liver or spleen.

Gastric Emptying

  • Used to evaluate and detect abnormalities and diseases within the stomach.
  • Assess nausea and vomiting, abdominal pain, GERD (gastroesophageal reflux disease)

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Liver scans can help discover tumors of the liver.

A liver scan is a specialized radiology procedure used to examine the liver to identify certain conditions or to assess the function of the liver. A liver scan may also be used to follow the progress of treatment of certain conditions. This procedure may also be referred to as a liver-spleen scan because the spleen often is examined as well due to its proximity and close functional relationship to the liver. A liver scan is a type of nuclear radiology procedure. This means that a tiny amount of a radioactive substance is used during the procedure to assist in the examination of the liver.

The radioactive substance, called a radionuclide (radiopharmaceutical or radioactive tracer), is absorbed by normal liver tissue. The liver will absorb about 80 percent to 90 percent of the radionuclide dose and the spleen about 5 percent to 10 percent. The remainder of the radionuclide is absorbed by the bone marrow. The radionuclide used in liver scans is usually a form of technetium.

Once absorbed into the liver tissue, the radionuclide emits a type of radiation, called gamma radiation. The gamma radiation is detected by a scanner, which processes the information into a picture of the liver.

By measuring the behavior of the radionuclide in the body during a nuclear scan, the physician can assess and diagnose various conditions, such as tumors, abscesses, hematomas, organ enlargement, or cysts. A nuclear scan may also be used to assess organ function and blood circulation. The areas where the radionuclide collects in greater amounts are called “hot spots.” The areas that do not absorb the radionuclide and appear less bright on the scan image are referred to as “cold spots.” Other related procedures that may be used to diagnose problems of the liver include abdominal x-rays, abdominal ultrasound, computed tomography (CT scan) of the abdomen or liver, or a liver biopsy. Please see these procedures for additional information.

(courtesy of Brigham and Womans Hospita)

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Renal Scans are used to examine the kidneys and to detect any abnormalities, such as tumors or obstruction of the renal blood flow.

Studies may be performed to determine the rate at which the kidneys are filtering a patient’s blood. These studies use a radiopharmaceutical, called Technetium DTPA (Tc 99m DTPA). This radiopharmaceutical also can identify obstruction (blockage) in the collecting system. To study how well the tubules and ducts of the kidney are functioning, the radiopharmaceutical Technetium MAG3 is used. Studying tubular function is a good indicator of overall renal function. In many renal diseases, one of the first things that disappears or diminishes is the tubular function.

Candidates for a kidney nuclear medicine scan are patients who have:

  • renal failure or chronic renal failure
  • obstruction in their urine collection systems
  • renal artery stenosis
  • a kidney transplant

(coutesy of Collette L. Placek answers.com)

thyroid

 

A thyroid scan is used to evaluate the health, function and structure of your thyroid gland. Thyroid scans are usually 2-day procedures. The first day, you will be given a radioactive iodine capsule that will be taken in by the thyroid gland. You will be asked to return in 3-4 hours on the same day. On the second day, depending on what your physician ordered, you will also be asked to return in 24 hours or 72 hours for thyroid imaging. While images are taken, you will be asked to lie still for about 30 minutes.

A thyroid that is enlarged or pushed off to one side could indicate a tumor. Nodules will absorb more or less iodine and will appear darker or lighter on the scan (usually lighter if tumor). If part of the thyroid appears lighter, it may indicate a possible thyroid problem.

The computer will also show the percentage of iodine that has collected in your thyroid gland. If your gland collects too much or too little of the radiotracer, this can cause hypothyroidism or hyperthyroidism.

Other conditions under which the test may be performed:

  • Anaplastic carcinoma of the thyroid
  • Colloid nodular goiter
  • Goiter
  • Medullary carcinoma of thyroid
  • Multiple endocrine neoplasia (MEN) II
  • Papillary carcinoma of the thyroid
  • Toxic nodular goiter