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Molecular imaging is a relatively new discipline that allows the biological processes taking place in the body to be viewed at a cellular and molecular level. This breakthrough enables doctors to identify disease in its earliest stages, often well before they would be seen on CT and MR images and would otherwise require invasive surgery or biopsy – the removal of tissue for examination under the microscope. Molecular imaging procedures are used to diagnose and manage the treatment of brain and bone disorders, cancer, gastrointestinal disorders, heart and kidney diseases, lung and thyroid disorders.
The biochemical activity of the cells changes when disease occurs and, as it progresses, this abnormal activity starts to affect the body and cause changes to bones and tissue that might not be noticed using conventional CT or MRI scans. Cancer cells, for example, begin by multiplying at an increase rate and then form a mass or tumor. By identifying these changes sooner, doctors can take remedial action at a much earlier stage of the disease than they could previously.
Most molecular imaging procedures are carried out with a PET or SPECT imaging device. A very small amount of a radioactive substance, called a radiopharmaceutical, is usually injected into the patient’s bloodstream prior to the scan. Depending on the part of the body being targeted, different radiopharmaceuticals are used. These radiopharmaceuticals attach themselves to the target organ or specific cells and are detected by the imaging device, which shows how they are distributed in the body. This distribution pattern helps doctors understand how well the organs and tissues are functioning.
Molecular imaging procedures are non-invasive. The amount of ionizing radiation used in these procedures is small; With regards to the benefits of an accurate diagnosis and treatment doctors and manufacturers, such as Siemens, are working together to minimize radiation dose, and further reduce the risk involved. Nevertheless, women should always inform their physician or X-ray technologist if there is any possibility that they are pregnant.
For a comparison of typical effective doses in molecuar imaging and medical examinations using X-rays, please view this chart.