PET/CT

Positron Emission Tomography aided by an Anatomical Computed Tomography Scan

A PET-CT scan takes CT pictures of the structures of your body. At the same time, a mildly radioactive drug shows up areas of your body where the cells are more active than normal. The scanner combines both of these types of information. This allows your doctor to see any changes in the activity of cells and know exactly where the changes are happening.

This is helpful in for:

  • detecting cancer.
  • determine whether a cancer has spread in the body.
  • assess the effectiveness of a treatment plan, such as cancer therapy.
  • determine if a cancer has returned after treatment.
  • determine blood flow to the heart muscle.
  • determine the effects of a heart attack, or myocardial infarction, on areas of the heart.
  • identify areas of the heart muscle that would benefit from a procedure such asangioplasty or coronary artery bypass surgery (in combination with a myocardial perfusion scan).
  • evaluate brain abnormalities, such as tumors, memory disorders, seizures and other central nervous system disorders.
  • map normal human brain and heart function.

A PET/CT scan (Positron Emission Tomography assisted by an Anatomical Computed Tomography Scan) is a type of nuclear medicine imaging that takes CT pictures of a patient’s body structures.  While the photography is taking place, a mildly radioactive drug called radiopharmaceuticals (or radiotracers) appears in area of the body where the patient’s cells are more active than normal. The radiotracer is either injected into the body, swallowed, or inhaled, and the emission are detected by a specialized camera or imaging device.

The PET scanner is a large machine that has a round opening in the middle. Inside the circular area are multiple rings or detectors that record the emission of energy from the radiotracers found within the patient’s body. The scanner combines these two types of information, which allows the physician to diagnose any changes in the activity of cells, and allows him to determine exactly where the changes are occurring.

A CT scanner is a large box-like machine with a short tunnel in the center of the device. Patients lie on a narrow examination table or bed that slides in and out of the tunnel. X-ray tubes and electronic x-ray detectors are located opposite of each other, and are referred to as a gantry. The imaging computer is located in a separate control room. The technician remains in direct visual contact of the patient and will normally have the ability to converse with the patient via speaker and microphone.

Combination PET/CT scanners take elements from both machines to operate, and even look like both scanners.

This is helpful for a number of diagnoses, such as:

  • Detecting cancer.
  • Determining if a type of cancer has spread within he body.
  • Assessing the effectiveness of a treatment plan, such as cancer therapy.
  • Determining if a cancer has returned after treatment.
  • Determining blood flow to the heart muscle.
  • Determining the effects of heart attack or myocardial infarction on areas of the heart.
  • Identifying the areas of the heart muscle that would benefit from a procedure such as angioplasty or coronary artery bypass surgery (that works in combination with a myocardial perfusion scan).
  • Evaluating brain abnormalities: Memory Disorders, Seizures, Tumors, and other central nervous system disorders.
  • Map human brain and heart function.

In addition to scanning for many different types of cancers, PET/CT scanning is also useful for diagnosing heart disease, endocrine, gastrointestinal and neurological disorders, in addition to other abnormalities within the body.

Preparation for the scan is relatively simple, requiring patients to wear a hospital gown or their own clothing. In specific cases with women who are pregnant or breastfeeding, with patients who are taking certain types of medication, patients with allergies, or patients with diabetes need to inform their doctors.

Metal objects, such as dentures, eyeglasses, hairpins, hearing aids, and jewelry may affect the overall quality of the CT images and should be removed prior to exam. It is also important to remain stationary during the testing procedures, as to preserve the integrity of the scan. Testing usually lasts around half an hour, although can go longer if necessary.

The doctor may request that the patient does not eat anything for several hours before the exam, as it may affect the distribution of the PET tracer. This can lead to a poor quality scan, or the necessity to repeat scanning attempts.

The procedure itself is painless, and rarely has any significant side effects. Radiotracers that are taken intravenously, inhaled, or swallowed lead to minimal but generally manageable side effects such as mild discomfort. Other procedures, such as catheter insertion, can lead to a more prolonged sensitivity.

After the administration of these nuclear medicine scans, the patient can usually resume his/her normal daily activities unless otherwise noted by a physician.  The radiotracer itself will eventually lose its radioactivity and disperse over time, passing through during bowel movements.  Drinking generous portions of water after testing will also help to remove any excess traces.

SDMI's PET/CT Scan Experience

How does a PET Scan work?