X-rays, CT/CAT Scans and MRI Deciphered

Diagnostic imaging techniques help narrow the causes of an injury or illness and ensure that the diagnosis is accurate. Images show bones, organs, muscles, tendons, nerves, and cartilage. Techniques include X-rays, computed tomography (CT/CAT) scans and magnetic resonance imaging (MRI). X-rays (radiographs) are the most common and widely available diagnostic imaging techniques. The injured part of the body is positioned on the X-ray machine and photographed from several angles. The X-ray machine sends electromagnetic waves (radiation) to create images, which reflect the internal structure of the area. Bones, tumors, and other dense matter appear white or light because they absorb the radiation. Less dense soft tissues and breaks in bone let radiation pass through, making them look darker on the X-ray film. Sometimes, to make certain organs stand out in the picture, barium sulfate or a dye is administered prior to imaging. X-rays are good for assessing an injury and providing a low-cost, first view of a fracture, bone degeneration, infection, or tumor. X-rays do not show the soft tissues and may not show as much detail as an image produced using newer, more powerful techniques. Computed tomography (CT/CAT) is a modern imaging tool that combines X-rays with computer technology to create a more detailed, cross-sectional image of the body. A CT scan shows the size, shape, and position of structures that are deep inside the body, such as organs, tissues or tumors. For a CT scan, the patient lies as motionless as possible on a table that slides into the center of the cylinder-like CT scanner. An X-ray tube slowly rotates around the patient, taking many pictures from all directions. A computer combines the images to produce a clear, two-dimensional view on a television screen. A CT/CAT Scan is able to image bone, soft tissue, and blood vessels. A CT scan may be necessary to diagnose severe trauma to the brain, spinal cord, chest, abdomen, or pelvis, and to pinpoint the size and location of tumors. Magnetic resonance imaging (MRI) is another modern diagnostic imaging technique that produces cross-sectional images of the body.

Unlike CT scans, an MRI works without radiation. The MRI tool uses magnetic fields and a sophisticated computer to take high-resolution pictures of bones and soft tissues. The physician needs to know about any implants, metal clips, or other metal objects in the body before an MRI scan is performed. The patient lies motionless on a table that slides into the tube-shaped MRI scanner. The MRI creates a magnetic field and pulse radio waves to the area of the body to be pictured. The radio waves cause tissues to resonate. A computer records the rate at which the body’s various parts (tendons, ligaments, nerves, etc.) give off these vibrations, and translates the data into a detailed, two-dimensional picture. An MRI is a better tool to diagnose damage to soft tissues: joints, tendons, ligaments, and cartilage, showing tissue difference between normal and abnormal. Physicians order MRIs to scan the brain, spine, neck, abdomen, and muscles.

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