MRI
What is MRI?
MRI (Magnetic Resonance Imaging) is a way to look inside the body without using X-rays. MRI can produce 2- or 3-dimensional images of what's going on inside a patient's body.
At Mercy, patients have access to both the 1.5T as well as the 3T MRI machines. The 1.5T MRI machine is 23 inches or 60 centimeters in size, while the 3T machine is 27¼ inches or 70 centimeters in size, which allows people who are claustrophobic or do not fit in the traditional 1.5T MRI equipment an alternative for their imaging needs.
Why is MRI important?
MRI can lead to early detection and treatment of disease. MRI pictures are extremely precise; so precise that physicians can often get as much information from MRI as they would from looking directly at the tissue. For this reason, MRI has the potential to reduce the number of certain diagnostic surgeries.
MRI uses no X-rays, and the magnetic fields MRI uses aren't known to be harmful.
What is MRI used for?
Because MRI can target specific atoms, it sees right through bone, and clearly defines soft tissue. MRI is especially valuable for helping to diagnose:
Brain and Nervous System Disorders
- Multiple Sclerosis can be seen in its earliest stages.
- Tumors can be distinguished from surrounding tissue.
- Disease in the base of the brain and interior of the spine can be easily examined.
- Hydrocephalus (abnormal fluid in the skull) can also be detected.
Cardiovascular Disease
- MRI can see right into the heart and blood vessels. When this procedure is used, it is called MRA (magnetic resonance angiography).
- Blood flow can be measured, and the effects of plaque in the arteries can be seen.
Cancer
MRI may be used to detect cancer in a variety of different organs and tissues.
Organ Disease
Images are so precise that many organs, including the liver, spleen, and pancreas and adrenal glands, can be seen in great detail.
Musculoskeletal Problems
MRI can detect injuries, disorders and diseases affecting the tendons, ligaments, cartilage, bone marrow, etc.
How does an MRI scanner work?
- Protons: The human body is composed of tiny particles called atoms. Under normal conditions, the protons inside of these atoms spin randomly.
- Magnet: A magnet creates a strong, steady magnetic field. This causes the protons to line up together and spin in the same direction, like an army of tiny tops.
- Radio Frequency (RF) Signal: A radio frequency signal is beamed into the magnetic field. The RF signal makes the protons move out of alignment - similar to what happens to a spinning top when someone hits it. When the signal stops, the protons move back to their aligned position and release energy.
- A Receiver Coil: A receiver coil measures the energy released by the disturbed protons. The time it takes the protons to return to their aligned position is also measured. These measurements provide information about the type of tissue in which the protons lie, as well as its condition.
- Computer: The computer uses this information to construct an image on a TV screen, showing the distribution of protons of certain atoms (usually hydrogen). The screen image can then be recorded on film or magnetic tape so that there is a permanent copy.
