Nuclear Medicine

Nuclear medicine is a medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease.

In nuclear medicine procedures, radionuclides are combined with other elements to form chemical compounds, or else combined with existing pharmaceutical compounds, to form radiopharmaceuticals. These radiopharmaceuticals, once administered to the patient, can localize to specific organs or cellular receptors. This property of radiopharmaceuticals allows nuclear medicine the ability to image the extent of a disease-process in the body, based on the cellular function and physiology, rather than relying on physical changes in the tissue anatomy. In some diseases nuclear medicine studies can identify medical problems at an earlier stage than other diagnostic tests. It would not be wrong to call Nuclear Medicine as "Radiology done inside out" or "Endo-radiology" because it records radiation emitting from within the body rather than radiation that is generated by external sources like Xrays.

Treatment of diseased tissue, based on metabolism or uptake or binding of a particular ligand, may also be accomplished, similar to other areas of pharmacology. However, the treatment effects of radiopharmaceuticals rely on the tissue-destructive power of short-range ionizing radiation.

In the future, nuclear medicine may provide added impetus to the field known as molecular medicine. As our understanding of biological processes in the cells of living organism expands, specific probes can be developed to allow visualization, characterization, and quantification of biologic processes at the cellular and subcellular levels.Nuclear medicine is an ideal specialty to adapt to the new discipline of molecular medicine, because of its emphasis on function and its utilization of imaging agents that are specific for a particular disease process.

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 order to:
Cancer

• 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 melanoma
• plan treatment
• evaluate response to therapy
• detect the recurrence of cancer
• detect rare tumors of the pancreas and adrenal glands

Renal

• analyze native and transplant kidney function
• detect urinary tract obstruction
• evaluate for hypertension related to the kidney arteries
• evaluate kidneys for infection versus scar
• evaluate and follow-up urinary reflux in pediatric patients

Heart

• 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)

Lungs

• scan lungs for respiratory and blood flow problems
• assess differential lung function for lung reduction or transplant surgery
• detect lung transplant rejection

Bones

• evaluate bones for fractures, infection and arthritis
• evaluate for metastatic bone disease
• evaluate painful prosthetic joints
• evaluate bone tumors
• identify sites for biopsy

Brain

• investigate abnormalities in the brain, such as seizures, memory loss and abnormalities in blood flow
• detect the early onset of neurological disorders such as Alzheimer disease
• plan surgery and localize seizure foci
• evaluate post-concussion syndrome

Other Systems

• identify inflammation or abnormal function of the gallbladder
• identify bleeding into the bowel
• assess post operative complication 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 children, nuclear medicine is also used to:

• investigate abnormalities in the esophagus, kidneys and intestines
• evaluate the openness of tear ducts and shunts in the brain and heart

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 laced with metaiodobenzylguanidine) used to treat adrenal gland tumors in adults and nerve tissue tumors in children

The animation below is briefing talk about the nuclear medicine and its challenge.