Magnetic Resonance Imaging (MRI) The MRI scan can complement or even supplant the CT scan in some cases. The images look similar to CT scan images, but there are no x-rays involved. The MRI scanner uses a powerful magnetic field to make certain particles in the body vibrate. Extremely sophisticated computer equipment measures the reaction and produces the images.
MRI has a few important advantages apart from no risk of x-ray exposure. Cross-sections can be obtained not only across the body, as in CT scanning, but also from front to back and from left to right. This lets your doctor see your body from all three directions. In some cases, the images provide more information and are superior to those obtained by CT scans. This is especially true for images of the central nervous system and the spine. In some other cases, CT scanning is more useful than MRI scanning.
MRI is not suitable under certain conditions. Implanted devices such as a pacemaker, clip or pump can be affected by the strong magnetic field.
Ultrasound This is a harmless and painless imaging technique. It is "non-invasive," meaning that nothing enters your body except sound waves.
The technique involves spreading a thin coating of jelly over a particular area of the skin, then bouncing
high-frequency sound waves through the skin onto internal organs. It works basically on the same principle as the sonar used by the navy to detect submarines, where sound waves are sent through the water and the "ping" of the sound bouncing back is analyzed.
