Doctors use several imaging techniques to see what is going on inside the body. This allows them to diagnose medical conditions without having to perform diagnostic or exploratory surgery, which involves a risk of complications for the patient. In addition to X-ray, one of the most commonly used and widely known of these techniques is magnetic resonance imaging.
MRI creates detailed images of body structures using a combination of computer-generated radio waves and a magnetic field. It has some advantages over X-ray in that it does not expose the patient to radiation and can produce pictures of soft tissues that are often not visible on X-ray. MRI is more expensive than plain film X-rays, although purchasing pre-owned MRI machines may help defray the cost involved. An MRI may be taken in a symptomatic area of the body to evaluate for certain conditions.
After a biopsy of the breast demonstrates cancer cells, the patient may then receive an MRI of the breast to gauge the extent to which the malignancy has spread. It is less common to perform MRI of the breast to screen for cancer. However, it may be used for screening in a patient for whom a mammogram, i.e., an X-ray of the breast, is not effective because the tissue is too dense. People who are at high risk for breast cancer may require breast MRI for screening instead of, or in addition to, mammography.
X-rays are very useful for identifying bone fractures and other osseous conditions, such as arthritis. However, there are many conditions of the musculoskeletal system that do not show up on X-ray very well because they involve soft tissues:
- Ligament sprains
- Cartilage tears
- Herniated disks
Following an X-ray to rule out a fracture, an MRI of the affected area may be able to positively identify one or more issues such as these.
An MRI is often the best, and sometimes the only, way to diagnose certain conditions of the central nervous system, comprised of the brain and spinal cord. For example, an MRI can reveal demyelination, or damage to the outer layer of the nerve cells, characteristic of multiple sclerosis. It is also used to diagnose strokes, brain tumors, and aneurysms. An aneurysm is a blood vessel that becomes weak and starts bulging, and can sometimes break. Brain aneurysms are dangerous because they can disrupt the flow of blood to the brain.
In addition to these systems, MRIs can also be used to diagnose abnormalities of the pancreas, liver, spleen, kidneys, and other internal organs.