Nuclear Medical Imaging

Author:  Gesche Tallen, MD, PhD, Editor:  Maria Yiallouros, Reviewer:  Prof. Dr. med. Dr. h. c. Günter Henze, English Translation:  Hannah McRae, Last modification: 2015/04/22

In paediatric oncology, nuclear medical imaging (NMI) is mainly used to diagnose certain childhood cancers as well as their extent of spread. NMI provides pictures of both structure and function of organs.

Nuclear medicine uses substances (so-called radiopharmaceuticals) that are composed of small amounts of radioactive agents (radionuclides) carried by so-called pharmaceuticals. These radiopharmaceuticals are introduced into the patient's body by inhalation, swallowing or injection. The radiopharmaceutical is designed to accumulate in body parts with increased metabolism.

This increased metabolism could be normally associated with a growth zone of a bone, for example. It could also be indicative of an abnormality, such as cancer. Once accumulated in a metabolically active body region, the radiopharmaceutical emits radiation known as gamma rays (similar to x-rays, please see X-ray). The emitted radiation is detected by special cameras (gamma cameras) that work with computers to provide digital images of the body region being examined.

During this imaging procedure, the patient is asked to lie down. Then the camera is placed a few inches over the patient’s body. Pictures are taken over the next few minutes. In order to obtain valid images without artefacts, mild sedation is usually recommended for small children, so they sleep and do not move during the procedure.

The radioactive agents in a radiopharmaceutical usually have a very short half-life. That means that the radioactivity usually cools down fast and that the patient does not become a radioactive source. The amount of radiation in a typical nuclear imaging procedure is comparable with that received during a diagnostic X-ray (please see X-ray). The amount of radioactivity received in a standard diagnostic procedure is kept within safe limits. The most commonly used radionuclide is Technetium (99mTc), which is used in skeletal scintigraphy , for example (please see below).

The results of a nuclear medical imaging procedure are usually interpreted by a nuclear medical specialist. Nuclear medical imaging is usually only performed on children or teenagers (under 18 years of age) after an informed consent has been obtained by the parent or legal guardian.

The following nuclear medical imaging procedures are presented on the next pages: