Pet Scan

Pet Scan
0 March 12, 2015

A positron emission tomography (PET) scan is an imaging test that uses a radioactive substance called a tracer to look for disease in the body.
PET scan uses radiation, or nuclear medicine imaging, to produce 3-dimensional, color images of the functional processes within the human body. The machine detects pairs of gamma rays that are emitted indirectly by a tracer (positron-emitting radionuclide), which is placed in the body on a biologically active molecule. The images are reconstructed by computer analysis.
Before carrying out a PET scan, a radioactive medicine is produced in a cyclotron (a type of machine). The radioactive medicine is then tagged to a natural chemical. This natural chemical could be glucose, water, or ammonia. The tagged natural chemical is known as a radiotracer. The radiotracer is then inserted into the human body
When it is inside, the radiotracer will go to areas inside the body that use the natural chemical. For example, FDG (fluorodeoxyglucose – a radioactive drug) is tagged to glucose to make a radiotracer. The glucose goes into those parts of the body that use glucose for energy. Cancers, for example, use glucose differently from normal tissue – so, FDG can show up cancers areas of spread.
A PET scan shows how organs and tissues are working. This is different than magnetic resonance imaging (MRI) and computed tomography (CT), which show the structure of and blood flow to and from organs.
An advantage of a PET scan is that it can show how well certain parts of your body are working, rather that showing what it looks like.
They’re particularly helpful for investigating confirmed cases of cancer, to determine how far the cancer has spread and how well it’s responding to treatment.

A PET scan can reveal the size, shape, position, and some function of organs.
Diagnose cancer, heart problems, and brain disorders; See how far cancer has spread
Repeated PET scans may be taken over time to check how well you are responding to treatment for cancer or other illness.
A normal result means there were no problems seen in the size, shape, or position of an organ. There are no areas in which the tracer has abnormally collected.
Abnormal results depend on the part of the body being studied. Abnormal results may be due to:

  • Change in the size, shape, or position of an organ
  • Cancer
  • Infection

PET scans are often combined with computerized tomography (CT) scans to produce even more detailed images. This combination scan is called a PET/CT.
They may also occasionally be combined with a magnetic resonance imaging (MRI) scan. This combination scan is called a PET-MRI scan.

Multiple bony and visceral metastasis of breast origin.

multiple bony and lung metastasis of uterine carcinnoma.


shoulder, lung and pelvic metastasis before chemotherapy.

good response after chemotherapy.

Posted in Diagnosis by emad