What is General Nuclear Medicine?
Nuclear medicine is a branch of medical imaging that uses small amounts of radioactive material to diagnose and determine the severity of or treat a variety of diseases, including many types of cancers, heart disease, gastrointestinal, endocrine, neurological disorders and other abnormalities within the body. Because nuclear medicine procedures are able to pinpoint molecular activity within the body, they offer the potential to identify disease in its earliest stages as well as a patient’s immediate response to therapeutic interventions.
Nuclear medicine imaging procedures are noninvasive and, with the exception of intravenous injections, are usually painless medical tests that help physicians diagnose and evaluate medical conditions. These imaging scans use radioactive materials calledradiopharmaceuticals or radiotracers.
Depending on the type of nuclear medicine exam, the radiotracer is either injected into the body, swallowed or inhaled as a gas and eventually accumulates in the organ or area of the body being examined. Radioactive emissions from the radiotracer are detected by a special camera or imaging device that produces pictures and provides molecular information.
In many centers, nuclear medicine images can be superimposed with computed tomography (CT) or magnetic resonance imaging (MRI) to produce special views, a practice known as image fusion or co-registration. These views allow the information from two different exams to be correlated and interpreted on one image, leading to more precise information and accurate diagnoses. In addition, manufacturers are now making single photon emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/computed tomography (PET/CT) units that are able to perform both imaging exams at the same time. An emerging imaging technology, but not readily available at this time is PET/MRI.
What are some common uses of the procedure?
Physicians use radionuclide imaging procedures to visualize the structure and function of an organ, tissue, bone or system within the body.
In adults, nuclear medicine is used to:
- visualize heart blood flow and function (such as a myocardial perfusion scan)
- detect coronary artery disease and the extent of coronary stenosis
- assess damage to the heart following a heart attack
- evaluate treatment options such as bypass heart surgery and angioplasty
- evaluate the results of revascularization procedures
- detect heart transplant rejection
- evaluate heart function before and after chemotherapy (MUGA)
- scan lungs for respiratory and blood flow problems
- assess differential lung function for lung reduction or transplant surgery
- detect lung transplant rejection
- evaluate bones for fractures, infection and arthritis
- evaluate for metastatic bone disease
- evaluate painful prosthetic joints
- evaluate bone tumors
- identify sites for biopsy
- investigate abnormalities in the brain in patients with certain symptoms or disorders, such as seizures, memory loss and suspected abnormalities in blood flow
- detect the early onset of neurological disorders such as Alzheimers disease
- assist in surgical planning and localize seizure foci
- evaluate for abnormalities in a chemical in the brain involved in controlling movement in patients with suspected Parkinsons disease or related movement disorders
- evaluation for suspected brain tumor recurrence, surgical or radiation planning or localization for biopsy
- identify inflammation or abnormal function of the gallbladder
- identify bleeding into the bowel
- assess post-operative complications of gallbladder surgery
- evaluate lymphedema
- evaluate fever of unknown origin
- locate the presence of infection
- measure thyroid function to detect an overactive or underactive thyroid
- help diagnose hyperthyroidism and blood cell disorders
- evaluate for hyperparathyroidism
- evaluate stomach emptying
- evaluate spinal fluid flow and potential spinal fluid leaks
In adults and children, nuclear medicine is also used to:
- stage cancer by determining the presence or spread of cancer in various parts of the body
- localize sentinel lymph nodes before surgery in patients with breast cancer or skin and soft tissue tumors.
- plan treatment
- evaluate response to therapy
- detect the recurrence of cancer
- detect rare tumors of the pancreas and adrenal glands
- analyze native and transplant kidney blood flow and function
- detect urinary tract obstruction
- evaluate for hypertension related to the kidney arteries
- evaluate kidneys for infection versus scar
- detect and follow-up urinary reflux
In children, nuclear medicine is also used to:
- investigate abnormalities in the esophagus, such as esophageal reflux or motility disorders
- evaluate the openness of tear ducts
- evaluate the openness of ventricular shunts in the brain
- assess congenital heart disease for shunts and pulmonary blood flow
Nuclear medicine therapies include:
- Radioactive iodine (I-131) therapy used to treat some causes of hyperthyroidism (overactive thyroid gland, for example, Graves disease) and thyroid cancer
- Radioactive antibodies used to treat certain forms of lymphoma (cancer of the lymphatic system)
- Radioactive phosphorus (P-32) used to treat certain blood disorders
- Radioactive materials used to treat painful tumor metastases to the bones
- I-131 MIBG (radioactive iodine labeled with metaiodobenzylguanidine) used to treat adrenal gland tumors in adults and adrenal gland/nerve tissue tumors in children