If you have ever passed through the security area of an airport or had a complete dental exam, you have likely encountered scanning and x-ray equipment. Scanning technology has become so advanced that it can detect a wider range of health problems than ever before. Scans are helpful in identifying underlying health problems that cannot otherwise be revealed through a regular medical exam. If you have symptoms that bear further investigation, your physician may refer you for diagnostic imaging, such as an MRI, CT or PET scan. What exactly are these scans, and which health problems are they used to detect?
An MRI, or magnetic resonance imaging (MRI), is useful in detecting cancers, structural abnormalities, and health problems in the brain, muscles and heart. An MRI scan uses magnets rather than x-rays to produce a clear, high-contrast image, and there is no radiation involved. The magnets cause atoms in the body to produce emissions, which are detected by a scanner.
If you have been referred for an MRI, you will be asked to lie still on an exam table that slides into a narrow scanning cylinder. The scanning process typically takes 30 minutes.
The CAT Scan or CT Scan
A computed axial tomography (CAT), or CT scan, produces a series of very detailed cross-sectional views of bones and all types of body tissue, including muscles and blood vessels. A CT scan can show the exact location and size of a tumor, if present, as well as its relationship to surrounding tissue. It is usually the preferred method for detecting cancers and guiding biopsies and related treatments.
CT scans can also be used to detect pulmonary embolisms and aortic aneurysms, as well as vascular diseases that can lead to stroke or kidney failure. They can help diagnose injuries to skeletal structures and can detect congenital malformations of the heart and other organs, identify injuries to internal organs, or assess results of organ transplants.
For a CT scan, you will typically lie motionless on a CT exam table while a large scanning tube rotates around the table, as the table passes through the tube. The imaging tube scans so quickly – less than 30 minutes – that even children rarely need to be sedated to remain still during a CT scan. A contrast material may be administered via mouth or IV before your scan.
The PET Scan
A PET scan, or Positron Emission Topography (PET), is currently used to detect forms of cancer that are not easily identifiable via other scanning technologies. While CT scans detect structural changes in the body, PET scans detect functional changes in the body. A PET scan can detect differences in chemical and metabolic activity in the body using positively charged particles (radioactive positrons) that show up on a colored PET image. PET scans can pick up even the smallest areas of activity, making them good for detecting cancer cells. Cancer cells typically divide more rapidly than other cells, so they will show more metabolic activity than other cells.
If you have been referred for a PET scan, you will be asked to lie on an exam table that will pass through a tube-shaped scanner that is similar to a CT scanner. A radioisotope tracer will be administered via inhalation or IV. The PET equipment will continue scanning the tracer while it is active in your body, which can be 30 minutes or longer, depending on the size of the body area that is being scanned.
Click here to find a scanning facility near you and to learn more about different medical scans.