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Medical Physics: MRI's

A presentation about MRI's by Jacob Sobodic and Adrian Kristovic

Jacob Sobodic

on 25 April 2011

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Transcript of Medical Physics: MRI's

Medical Physics: MRI What is an MRI?
•Tumours in the chest, abdomen, pelvis.
•Evidence of heart problems
•Blockages of blood vessels such the aorta, renal arteries, arteries in the legs.
•Diseases of the liver and other abdominal organs such as the bile ducts, gallbladder, and pancreas.
•Diseases of the small intestine and rectum
•Cysts and solid tumors in the kidneys and other parts of the urinary system
•Tumours and other abnormalities in the reproductive organs
•Causes of pelvic pain in women such as fibroids, endometriosis and adenomyosis.
•Abnormalities in women undergoing evaluation for fertility.
•Breast cancer The MRI Machine looks like a large cylinder-shaped tube surrounded by a circular magnet. Patients lie on a movable table that retracts into the center of the magnet during operation. Physicians use the examination to help diagnose and monitor treatment for conditions such as: Advantages and Disadvantages: ADVANTAGES:
•MRI'S dont expose patients to radiation, so they can be safely used in people who may be vulnerable to the effects of radiation (such as pregnant women, babies).
•Shows blood travel through organs and blood vessels, allowing problems with blood circulation, such as blockages, to be identified.
• Dieseases of the soft-tissue parts of the body (such as the heart, liver and many other organs) can be identified unlike other imaging methods.
•The contrast material used (Gadolinium) is less likely to give an allergic reaction compared to the iodine-based contrast materials used in x-rays and CT scanning
•Implanted medical devices that contain metal (e.g, pacemakers) may malfunction due to the magnetic field produced
•During an MRI scan patients have to stay still for 30 minutes up to an hour
•MRI scanners can be very noisy and depending on the part of the body being scanned, your head may need to be inside the MRI scanner tube, and and can make patients caustraphobic
•MRI scan quality can be affected by movement, which makes them unsuitable for investigating problems such as mouth tumours, due to coughing or swallowing
•There is a very slight risk of an allergic reaction if contrast material is injected. The contrast agent can also cause Nephrogenic systemic fibrosis in allergic patients. This is a serious disease that causes fibrosis of skin, joints, eyes, and internal organs How MRI Works: Magnetic Resonance Imaging (MRI) is a noninvasive medical examination that allows physicians to diagnose and monitor treatment of medical conditions.

MRI uses a powerful magnetic field, hydrogen proton energy in the patient, radio frequency signals and computer technology to produce detailed pictures of organs, soft tissues, and bone.

The detailed MRI images give physicians a better evaluation of different parts of the body and determine the presence of certain diseases, that may not be picked up by other imaging methods such as X-Rays, Ultrasound and CAT Scanning. What is MRI? Adrian Kristovic and Jacob Sobodic What does the MRI machine look like? 1.Patient is scanned by magnetic coils that emit frequency on the area to be examined
2.Creates a magnetic field that runs down the centre of the patient. Half of the billions of hydrogen atoms of the patient go to the North Pole (Head) and the other half go to the South Pole (Feet) of the patient.
3.When the magnetic current acts on the body, the atoms rotate on a different axis of the hydrogen protons, in contrast to their natural alignment. When the magnetic current is removed, the atoms return to their natural alignment.
4. As they do this they release energy which emits a radio frequency. The strength of this signal is recorded and sent to the computer
5.The computer produces a image with this data by using the Fourier Transform. The Fourier Transform uses the signal’s strength to form the image. Soft tissue has a quicker re alignment time than denser tissue (e.g. tumor). The soft tissue is shown as black and the denser tissue as white. What the MRI can evaluate: •Organs of the chest and abdomen—including the heart, liver, biliary tract, kidneys, spleen, bowel, pancreas and adrenal glands.
•Pelvic organs including the reproductive organs in the male (prostate and testicles) and the female (uterus, cervix and ovaries).
•Blood vessels (MR Angiography).
•Breasts. Science Behind the MRI: The Magnetic field is the area around a magnet in which a magnetic force is exerted. Moving electric charges produce magnetic fields. Magnetic fields give power to other particles that come in contact with the magnetic field. MRI macines use this property of magnetisation to provide power to the hydrogen atoms of the body, and then the rest of the imaging
process occurs.
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