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How PET and CT Scans Work

Positron emission tomography (PET) and computed tomography (CT) are both diagnostic imaging tools physicians use to scan a person’s body to determine if they have certain types of cancer or cardiac or neurological disorders—like a brain aneurysm. A very small amount of radioactive glucose material, called a tracer, is injected into a vein. The body identifies the tracer as a form of sugar that is used for energy by all cells in the body.

One continuous full-body PET and CT scan usually lasts about 40 minutes. The PET scan captures images of tiny changes in the body’s metabolism caused by the growth of abnormal cells. At the same time, images from the CT scan allow physicians to pinpoint the exact location, size and shape of the diseased tissue or tumor.

Each imaging test has particular benefits and limitations, but when the results of PET and CT scans are fused together, the combined image provides complete information on the cancer location and metabolism.

Working together, PET and CT scans can also determine:

  • The difference between scar tissue from radiation treatments and active tumor tissue.
  • If a mass or lesion is cancerous.
  • If enlarged lymph nodes are a result of cancer.
  • If normal-size lymph nodes or normal-appearing tissue contains cancer.
  • How a tumor may respond to treatment.
  • If a patient suffering from dementia has Alzheimer’s disease.

What Are the Risks and Benefits?

The risks for PET and CT scans are almost non-existent; however, the benefits are highly measurable:

  • The information provided by PET examinations is unique and often unattainable using other imaging procedures.
  • For many diseases, PET scans yield the most useful information needed to make a diagnosis or to determine appropriate treatment.
  • PET is less expensive and may yield more precise information than exploratory surgery.
  • By identifying changes in the body at the cellular level, PET imaging may detect the early onset of disease before it is evident on other imaging tests, such as CT scans or MRIs.

PET/CT scanning services:

  • Brain
  • Alzheimer’s
  • Breast
  • Colorectal
  • Esophageal
  • Gastric
  • Head
  • Liver
  • Lung
  • Lymphoma
  • Melanoma
  • Neck
  • Ovarian
  • Renal cell carcinoma
  • Thyroid

Preparation for PET/CT Scans 

Download our PET/CT Scan brochure for detailed information on the PET/CT experience. If you have Diabetes or are on Insulin please download this brochure for information on the PET/CT scan experience.

Preparing for any medical procedure can be stressful, but with PET/CT scans, you don’t have to worry because they are completely painless. After fasting for approximately six hours, you will receive an injection of a radioactive glucose material. Following the injection, you will rest quietly for approximately 45 to 70 minutes while the glucose is distributed throughout the body.

After the distribution is complete, you will be asked to lie on a table that slowly passes through the scanner.

The CT scan portion of the test sends X-rays through the body. These X-rays are then processed to make images that show the body structure. The PET portion of the test produces a whole-body map of the glucose distribution using X-ray images. The entire scanning process takes approximately 40 minutes.

Other tips for preparing for a PET/CT scan:

  • Wear comfortable clothing.
  • Take any prescribed medication unless instructed otherwise.
  • Notify your physician if you are pregnant or breastfeeding, or if you are diabetic.

Finding Out Your Results

A board-certified radiologist will review your images from the radioactive tracer and a report will be sent to your doctor within 24 to 48 hours. Your doctor will then discuss the results with you and explain what they mean.

If you would like to schedule an appointment, please call 678-312-3444.