Nuclear Medicine

Nuclear Medicine

What is nuclear medicine?

Nuclear medicine is a specialized area of radiology that uses very small amounts of radioactive materials, or radiopharmaceuticals, to examine organ function and structure and to provide diagnosis, management, treatment, and prevention of diseases. Nuclear medicine imaging is a combination of many different disciplines, including chemistry, physics, mathematics, computer technology, and medicine. This branch of radiology is often used to help diagnose and treat abnormalities very early in the progression of a disease, such as thyroid cancer.

Nuclear imaging examines organ function and structure, whereas diagnostic radiology is based on anatomy. Conventional X-ray or CT examinations pass through soft tissue, such as intestines, muscles, and blood vessels, therefore, contrast agents are used in nuclear imaging. For Nuclear Medicine examinations, the radioactive material is introduced into the patient's body (usually by injection into a vein), and is then detected by a machine called a gamma camera. There is usually a specific waiting time for the radioactive material to be distributed in the body or the organ of interest.

Some patients may think "That sounds dangerous." Approximately 90% of the radiopharmaceuticals, used in Nuclear Medicine have very short half-lives, which means that they decay rapidly and are inside the patient's body for a short time. Also, the total radiation dose is relatively small, similar to or sometimes even less then the dose used for CT and X-ray examinations.

What are the different types of nuclear medicine scans?

Scans are used to diagnose many medical conditions and diseases. Some of the more common tests include the following:

• Bone scans
  Used to detect bone metastases, diagnose osteomyelitis, evaluate
bone trauma such as fracture, aid in the diagnosis of inflammatory disease such as arthritis and Paget´s disease.
• Gallium Scans
  Used to diagnose active infectious and/or inflammatory diseases, tumors, and abscesses.
• Heart Scans
  Used to identify abnormal blood flow to the heart, to determine the extent of the damage of the heart muscle after a heart attack, and/or to measure heart function.
• Hepatobiliary scans (HIDA)
  Used to diagnose acute cholecystitis, evaluate extrahepatic biliary tract obstruction, detect bile leaks. Thyroid uptake & thyroid scans - used to diagnose the cause of hyperthyroidism: Graves' disease, thyroiditis, or hyperfunctioning thyroid nodule; evaluate ectopic thyroid tissue.
• Lung ventilation and perfusion scans (VQ scans)
  Used to diagnose pulmonary embolism and perfusion and ventilation post lung transplant,
• Lymphoscintigraphy
  Used for identification and localization of draining lymph node groups and sentinel nodes in breast cancer and melanoma.
• Octreoscans
  Used to detect and localize neuroendocrine tumors such as:
  • Carcinoid tumors
  • Paragangliomas
  • Gastrinomas
  • Pheochromocytomas
  • Neuroblastomas
  • Glucogonomas
  • Functioning and non-functioning anterior pituitary tumors
• Parathyroid scans
  Used to detect and localize parathyroid adenomas in patients with primary hyperparathyroidism prior to surgery.
• Renal scans
  Used to evaluate renal perfusion and function, renal trauma, renal transplants, renal collecting system obstruction and assist in the diagnosis of renovascular hypertension.
• Thyroid Scans
  Used to evaluate thyroid function.

How are nuclear medicine scans performed?

As stated above, nuclear medicine scans may be performed on many organs and tissues of the body. Each type of scan employs certain technology, radiopharmaceuticals, and procedures.

A nuclear medicine scan consists of a tracer (radiopharmaceutical) administration, taking images, and image interpretation. The amount of time between administration of the tracer and the taking of the images may range from a few moments to a few days, depending on the body tissue being examined and the tracer being used. The time required to obtain the images may also vary from minutes to hours.

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Are there special preparation requirements for the exam?

Your healthcare provider will tell you if there are specific instructions on eating prior to your exam and whether or not you should take your routine medications. Wear loose, comfortable clothing for your test. Discuss with your healthcare provider if you are claustrophobic or worried about lying still during the scan. He or she may order medication to help you relax during the procedure. The radioactive material used is made precisely for the time of your test, so it is very important that you be on time.

Inform the technician of all medications (over–the–counter and prescription) and herbs you are currently taking. There are medications that could possibly interfere with the radioactive materials given from the exam. Also, be sure to mention any recent imaging studies involving injected contrast media (dye) and oral or rectal contrast (such as in gastrointestinal studies) since they could also interfere.

If there is a chance that you may be pregnant, notify your healthcare provider.

What should I expect during the procedure?

Depending on the region being scanned, you may need to wear a hospital gown. Remove all jewelry, dentures and other metals that may affect the scan by blocking the rays from the tracer.

Prior to the scan, you will be given a small amount of radioactive material, either by injection or orally. As this moves throughout the body, it can then be traced using a special camera called a gamma camera and a computer. It eventually collects in the organ being examined and gives off special rays called gamma rays. The amount of radiation that is "taken up" and then gives off gamma rays in a specific organ or tissue is linked to the metabolic activity of that organ or tissue. For example, cells which are dividing rapidly (like cancer cells) may be seen as "hot spots" of metabolic activity since they absorb more of the radioavtive material. The gamma camera detects the rays and works with the computer to produce images and measurements of the organ or tissue.

It is possible that you will come in first for the administration of the tracer and then return later for the actual scan. Sometimes the entire procedure may be done during one visit. There are also exams that require multiple visits in a day or over a few days. The actual imaging time varies, but is generally less than an hour.

Prior to your exam, you may be asked to empty your bladder. As the tracer passes through the body, it eventually ends up in the bladder. If the bladder contains urine and tracer elements, it could possibly block the view of part of the pelvic bones if you are having a bone scan. When the exam starts, you will lie on a special exam table and be made as comfortable as possible. It is important for you to be able to lie still for the study. The technologist will be with you during the exam to assist in making you comfortable. The gamma camera may be close to the area of your body that is being examined while the images are formed or it could be contained in a large doughnut–shaped structure similar to a CT scanner. If this is the case, you will be placed into the opening while lying on the table. Once the images are obtained and the computer processes the data, a physician with specialized training in nuclear medicine checks the quality of the images to ensure that the optimal diagnostic study has been performed.

How long will the exam take?

1 hour (60min) to 2 days depending exam type.

Weight limit

400 pound weight limit.

For more information about Willowbrook Imaging & Diagnostic Services at the Methodist Willowbrook Hospital, please call 281-737-1234.

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