Diagnostic Magnetic Resonance Imaging (MRI)

Monday, October 20, 2014

Diagnostic Magnetic Resonance Imaging (MRI)

Magnetic resonance imaging (MRI) is a diagnostic method that uses a scanning exposure to magnetic fields and radio-frequency electromagnetic waves on the hydrogen atoms in the body.

MRI is a relatively new technology and is still being developed. This technology was first demonstrated on small test tube samples in 1975 by Paul Lauterbur US radiologists. He uses a projection technique similar to that used in computed tomography. In 1977, British physicist Peter Mansfield developed the echo-planar imaging technique that some years later can produce quality video images. Breakthroughs in enabling the reliable MRI machine, which began to enter the market in the 1980s.
Above their pioneering, Paul Lauterbur and Peter Mansfield was awarded the Nobel Prize in medicine in 2003.

How is the Scan performed?
As with CT Scans, MRI scans generally require you to lie inside a large tube that is shaped like a donut (though there is also an open MRI machine without the tube). MRI scanner and then emit a magnetic field strength of the earth's magnetic tens of thousands of times to parts of your body being studied.

Your body is made up almost entirely of hydrogen atoms. Each hydrogen atom has protons in its core that spins like a top on its axis. This round produces a very weak magnet. Under normal conditions, each has a hydrogen proton magnetic poles with different directions (random). When faced with the MRI magnetic field is very strong, the magnetic poles of the hydrogen protons become aligned, such as iron sand lined up neatly when approached by a magnetic rod. After the MRI magnetic field is turned off, the poles of the atoms will gradually lose alignment and return to its original position. When it is moved to its original position they will send a radio frequency signal that can be captured by an MRI machine and converted into an image with a particular computer. Variations in the location and signal strength will give a different image details.

 For example, the characteristics of radio waves generated by the different bones with blood, etc. The greater the amount of water in the body tissues, the higher the content of the hydrogen atom, the brighter the well results on the MRI images.

Long MRI scan varies, depending on the condition and the body part being studied. In general, MRI takes about 20 to 30 minutes (longer than the average scanning with CT). MRI scanners produce noise loud enough that you need to wear earplugs or headphones to keep the noise down to a tolerable level.
MRI is suitable for everyone, including pregnant women and children.

 However, MRI may not be the choice for you who use electronic devices or metal in the body such as pacemakers, defibrillators, cochlear implants, insulin pumps, artificial heart valves, etc. Strong magnetic field can make the device damaged. In contrast, the movement of the device in a magnetic field can also damage a very expensive MRI machine.

Preparation of MRI

Before scanning, you must remove all jewelry and other metal objects such as glasses, dentures and braces, hairpins and hearing aids. Credit cards, ATM cards and other electronic cards must also be removed because it can be damaged by magnetic fields. If you have a phobia of the narrow room and closed (agoraphobia / claustrophobia), you may need a sedative.

Certain MRI exams require the injection of a special contrast agent (paramagnetic) into a vein or joints. This contrast agent serves to clarify the pathological changes in the body part being studied. Contrast agents for MRI does not contain iodine (iodine) and does not have the same chemistry with a contrast agent for CT scans or regular x-rays.