What is a PET Scan?
A positron emission tomography (PET) scan examines the body's chemistry, producing pictures of the body's biological functions. Functional changes often occur in the body before physical or structural changes, allowing for earlier detection. Because PET can depict minute chemical and physiological changes related to metabolism, PET is able to detect certain diseases before other imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI), which obtain information from gross anatomy and structure.

The PET scanner resembles a CT scanner, but has a much larger opening. PET detects and records the signals emitted by a tracer, a radioactive material injected into the patient prior to the scan. The tracer distributes throughout the body and is processed by the organs being evaluated. The signals are then reassembled into actual images through a computer.

Benefits of PET
Since disease is a biological process, and PET is a biological imaging examination, PET is able to recognize and identify the stage of most cancers, often before they can be revealed through other tests. With the ability to map very subtle changes of function in the brain and heart, PET can also provide valuable early information to physicians about heart disease and many neurological disorders, such as Alzheimer's.

PET images produced in the scanning process are used by physicians to diagnose and manage patient treatment plans for many diseases in the fields of oncology, cardiology and neurology. A PET scan can detect extremely small cancerous tumors and is the most accurate, non-invasive method for distinguishing benign from malignant tumors. This alleviates patients from costly, often painful diagnostic surgeries and signifies treatment options in the earlier stages of the disease. Physicians can select more effective therapies and improve patient care using information obtained from PET images. The early detection capacity of PET can save time and reduce healthcare costs. A PET scan is safe and painless. The radiation exposure level is similar to that associated with conventional CT scanning.

Any special precautions?
The radioactive glucose (tracer) given in the injection prior to the scan is not dangerous to the patient. Every cell in the human body needs glucose (also known as sugar) for it to function. Radioactive glucose must pass numerous quality control measures to qualify for use in any patient injection.

Generally, pregnant women should not undergo a PET scan. Under circumstances where the benefits outweigh the risks, PET scans of certain body parts may be allowed. If the patient is breast feeding, she should suspend nursing for 18 hours (breast milk may be pumped and stored for 18 hours prior to use).

Patients with diabetes may need their blood glucose level stabilized prior to the appointment.