MRI Flashcards
how does an MRI scan work?
The scanner’s magnetic field aligns the far weaker magnetic fields of all the protons in all the hydrogen atoms in the water contained in the body’s tissues.
The scanner then uses radio waves to bombard the part of the brain that is to be imaged.
After the radio waves are turned off, the protons return to their original alignment. In the process, they emit a weak radio signal, known as their magnetic resonance. The intensity of this magnetic resonance is proportional to the density of the protons in the various tissues, and hence to the percentage of water that they contain.
Special sensors detect the varying intensities of this resonance and relay this information to a computer.
The computer processes this information to create images of tissue sections along various axes.
Why is it easier to detect diseased or damaged tissue in a scan?
Diseased or damaged tissues generally contain more water, which allows them to be detected with MRI.
What is the contrast agent used in this scan?
For MRI scans, as for CT scans, the patient may be injected with a contrast agent. The agents most commonly used for MRIs are compounds of the element gadolinium.
