What are pet scans? what exactly is a pet scan?

Positron : Positron emission tomography (pet) is a test that uses a special type of camera and a tracer (radioactive chemical) to look at organs in the body. The tracer usually is a substance (such as glucose) that can be used (metabolized) by cells in the body. During the test, the tracer liquid is put into a vein in your arm. The tracer moves through your body, where much of it collects in the specific organ or tissue. The tracer gives off tiny positively charged particles (positrons). The camera records the positrons and turns the recording into pictures on a computer. Pet scan pictures do not show as much detail as computed tomography (ct) scans or magnetic resonance imaging (MRI) because the pictures show only the location of the tracer. The pet picture may be matched with those from a ct scan to get more detailed information about where the tracer is located. A pet scan is often used to evaluate cancer, check blood flow, or see how organs are working.

Positron Emission: These studies are done by injecting a special "dye" that is attached to a specific molecule. Most of the pet today is done using FDG (a glucose/sugar look-a-like molecule). Wherever this molecule is used/concentrated, the pet scan is brighter. Hence, tumors/infections (which use a lot of energy/sugar/fdg) are bright on such studies. More: http://en.Wikipedia.Org/wiki/positron_emission_tomography.

Physiology of lesion: Pet scans most often use a radioactive form of glucose, the energy source for most of the cells in our bodies. The pet scanner can detect and measure how much of the radioactive glucose analog, f-18 fdg, is in a particular organ or region. The areas using more glucose are hyper metabolic and generally more worrisome. Our brains and sometimes hearts prefer glucose as food, making it hard to see.

PET: PET scan usually refers to PET-CT scan where a CT scan is fused with a PET scan for interpretation. The CT is helpful for anatomic localization of uptake on PET. The PET portion of the exam shows metabolic activity (glucose uptake). Glucose is a nonspecific tracer and can be taken up in inflammatory, infectious, or malignant conditions.

PET: Positron emission tomography uses a radio tracer labelled glucose to assess glucose use by the body and attempt to find areas of increased use suggesting abnormal tissue. The CT scan shows the areas. Most often used to see if abnormal area on the ct scan is metabolically active. Hope this helps