Nuclear Medicine is a specialized area of radiology that uses very small amounts of radioactive materials, known as radiopharmaceuticals or isotopes, to examine the structure and function of organs. Since x-rays pass through soft tissue, such as intestines, muscles, and blood vessels, these contrast agents must be used to visualize certain parts of the body. Nuclear Medicine procedures use the low-dose radioactive isotopes to trace the functioning of the lungs, kidneys, stomach, colon, endocrine and neurological systems. It also helps diagnose certain tumors, metastatic disease and infections in the body very early in the progression of a disease, such as thyroid cancer, at a time when there may be a more successful treatment.

Most Nuclear Medicine studies require the injection of an isotope with an immediate series of images being taken. Depending on the body tissue being examined, taking the images may be delayed by an amount of time specified by a Radiologist. This imaging study is performed using dual-headed camera, known as a gamma camera.

Nuclear medicine techniques include:

• Positron emission tomography (PET)
• Single photon emission computed tomography (SPECT)
• Cardiovascular imaging
• Bone scanning

Nuclear medicine imaging is useful for detecting:

• tumors
• aneurysms (weak spots in blood vessel walls)
• irregular or inadequate blood flow to various tissues
• blood cell disorders and inadequate functioning of organs, such as thyroid and pulmonary function deficiencies

PET and PET/CT Imaging

When first developed Positron Emission Tomography (PET) imaging was utilized primarily as a research tool; this was because of the expense of the scanner and the difficultly in generating the needed radioisotope by an on-site cyclotron. In the last several years PET imaging has come into routine clinical use as radioisotope became commercially available and the price of PET scanners decreased.

Today, PET imaging has been combined with CT to provide anatomic and metabolic information from a single exam in a single system. PET and PET/CT are used primarily in the diagnosis and staging of cancer. The PET exam pinpoints metabolic activity in cells and the CT exam provides an anatomical reference. When these two scans are fused together, a physician can view metabolic changes in the proper anatomical context of a patient's body.

The most common applications include the initial work-up of a solitary pulmonary nodule which may have been initially detected through CT imaging. Other PET/CT indications include the initial diagnosis, staging or restaging for Non-Small Cell Lung Cancer, Head/neck Cancer - (Excluding CNS), Thyroid Cancer, Colorectal Cancer, Lymphoma, Melanoma, Esophageal Cancer and Breast Cancer

PET imaging is also a valuable tool in neuroradiology, helping to define recurrent tumor from radiation necrosis in brain neoplasms. Outside of oncology, PET imaging is utilized in other neurological conditions such as epilepsy, neuro-degenerative disorders and psychiatric illness.