|PET/CT scanner ||SPECT scanner|
In nuclear medicine examinations are based on the use of small amounts of radioactive materials (tracers) evaluating the function of the organ, tissue or bone. In clinical physiology the organ function is measured directly by physiological measurements without use of radioactive material, as lung function and blood pressure. The aim is to assess organ function rather than morphology. This is how our examinations differ from X-ray or ultrasound that determines the presence of disease based mainly on their structural appearance or anatomy.
For nuclear medicine investigations a radiotracer is injected into the body, or inhaled as a gas and eventually accumulates in the organ or area of the body being examined. Radioactive emissions from the radiotracer are detected by a special camera or imaging device that produces pictures and detailed molecular information: Gamma camera, SPECT or PET scanner.
Positron emission tomography (PET)
PET is a nuclear medical imaging technique, by use of positron emitting tracers, that produces a three-dimensional image or picture of functional processes in the body.
Three-dimensional images of tracer concentration within the body are then reconstructed by computer analysis. Most modern scanners are combined PET and CT scanners enabling imaging of function (by PET) and detailed anatomy (by CT) during the same session, in the same machine. The most frequent indication for performing a PET/CT scan is diagnosing cancer and/or to explore the possibility of cancer metastasis. The most frequently used tracer is FDG, an analogue of glucose, where high FDG uptake shows the high tissue metabolic activity of cancer.
Other radiotracers are used in PET to image the tissue concentration of other types of molecules: PiB for the brain (dementia) and Rubidium for examination of the heart (ischemic heart disease).