MRI.pptx
- 2. • An MRI scanner is a large tube that contains powerful magnets. Person lie inside the tube during the scan.
- 3. MRI (magnetic resonance imaging) • An MRI (magnetic resonance imaging) scan is a painless test that produces very clear images of the organs and structures inside your body. MRI uses a large magnet, radio waves and a computer to produce these detailed images. It doesn’t use X-rays (radiation).
- 4. MRI scan can be used to examine almost any part of the body, including the: • Brain and spinal cord • bones and joints • breasts • heart and blood vessels • internal organs, such as the liver, womb or prostate gland
- 5. MRI SCAN ( Magnetic resonance imaging) • MRI is a type of diagnostic test that can create detailed images of nearly every structure and organ inside the body. MRI uses magnets and radio waves to produce images on a computer. MRI does not use ionizing radiation. Images produced by an MRI scan can show organs, bones, muscles and blood vessels.
- 6. • The MRI machine is a large, cylindrical (tube- shaped) machine that creates a strong magnetic field around the patient and sends pulses of radio waves from a scanner. Some MRI machines look like narrow tunnels, while others are more open.
- 7. • The strong magnetic field created by the MRI scanner causes the atoms in your body to align in the same direction. Radio waves are then sent from the MRI machine and move these atoms out of the original position. As the radio waves are turned off, the atoms return to their original position and send back radio signals. These signals are received by a computer and converted into an image of the part of the body being examined. This image appears on a viewing monitor.
- 8. • Because ionizing radiation is not used, there is no risk of exposure to radiation during an MRI procedure.
- 9. • The MRI scanner is operated by a radiographer, who is trained in carrying out imaging investigations. • They control the scanner using a computer, which is in a different room, to keep it away from the magnetic field generated by the scanner.
- 10. • During the scan, the scanner will make loud tapping noises. This is the electric current in the scanner coils being turned on and off.
- 11. • The scan lasts 15 to 90 minutes, depending on the size of the area being scanned and how many images are taken.
- 12. • Most of the human body is made up of water molecules, which consist of hydrogen and oxygen atoms. • At the centre of each hydrogen atom is an even smaller particle called a proton. Protons are like tiny magnets and are very sensitive to magnetic fields.
- 13. Mechanism of Operation • Under the powerful scanner magnets, the protons in your body line up in the same direction. • Short bursts of radio waves are then sent to certain areas of the body, knocking the protons out of alignment. • When the radio waves are turned off, the protons realign. This sends out radio signals, which are picked up by receivers.
- 14. • These signals provide information about the exact location of the protons in the body. • They also help to distinguish between the various types of tissue in the body, because the protons in different types of tissue realign at different speeds and produce distinct signals.
- 15. • In the same way that millions of pixels on a computer screen can create complex pictures, the signals from the millions of protons in the body are combined to create a detailed image of the inside of the body.
- 16. MRI with contrast • Some MRI exams use an injection of contrast material. The contrast agent contains gadolinium, which is a rare earth metal. When this substance is present in your body, it alters the magnetic properties of nearby water molecules, which enhances the quality of the images. This improves the sensitivity and specificity of the diagnostic image
- 17. • Contrast material enhances the visibility of the following: • Tumors. • Inflammation. • Infection. • Blood supply to certain organs. • Blood vessels.
- 18. • Metal and electronic items aren’t allowed in the exam room because they can interfere with the magnetic field of the MRI unit, cause burns or become harmful projectiles. These items include
- 19. • Jewelry, watches, credit cards and hearing aids — all of which can be damaged. • Pins, metal hair accessories, underwire bras and metal zippers, which can distort MRI images. • Removable dental work, such as dentures. • Pens, pocketknives and eyeglasses. • Body piercings. • Cell phones, electronic watches and tracking devices.
- 20. The general steps of an MRI scan