MRI - MAGNETIC RESONANCE IMAGING

What are my objectives while studying this topic?


Healthcare professionals use a range of imaging techniques to diagnose illnesses or to monitor the health of an individual. By studying this topic you’ll learn about Magnetic Resonance Imaging (MRI) and why this is important as a means to diagnosing illnesses.


Why is this important?


Fitness professionals monitor people to assess their fitness to improve their performance.


Healthcare professionals use physiological measurements to monitor the health of patients, to diagnose ill health and determine specific treatment for patients.


Can I get an introduction to this topic?


Yes, why not have a look at the following clip:


Moving sequence of MRI images of a head



So, let’s get to it: what is magnetic resonance imaging (MRI)?


Magnetic Resonance Imaging (MRI) is a relatively new technology. It has been in use for little more than 30 years (compared with over 110 years for X-ray radiography). The first MRI Image was published in 1973 and the first study performed on a human took place on July 3, 1977.


The MRI scan uses magnetic and radio waves, meaning that there is no exposure to X-rays or any other damaging forms of radiation.


Mri Scan

(First low intensity MRI Scan)


How does an MRI scanner work?


The patient lies inside a large, cylinder-shaped magnet. Radio waves 10,000 to 30,000 times stronger than the magnetic field of the earth are then sent through the body. This affects the body's atoms, forcing the nuclei into a different position. As they move back into place they send out radio waves of their own. The scanner picks up these signals and a computer turns them into a picture. These pictures are based on the location and strength of the incoming signals.


Mri Scanner

 

Our body consists mainly of water, and water contains hydrogen atoms. For this reason, the nucleus of the hydrogen atom is often used to create an MRI scan in the manner described above.


What does an MRI scan show?


Using an MRI scanner it is possible to make pictures of almost all the tissue in the body. The tissue that has the least hydrogen atoms (such as bones) turns out dark, while the tissue that has many hydrogen atoms (such as fatty tissue) looks much brighter. By changing the timing of the radiowave pulses it is possible to gain information about the different types of tissues that are present.

 

An MRI scan is also able to provide clear pictures of parts of the body that are surrounded by bone tissue, so the technique is useful when examining the brain and spinal cord.


Mri Scan 2

 

Because the MRI scan gives very detailed pictures it is the best technique when it comes to finding tumours (benign or malignant abnormal growths) in the brain. If a tumour is present the scan can also be used to find out if it has spread into nearby brain tissue.

 

The technique also allows us to focus on other details in the brain. For example, it makes it possible to see the strands of abnormal tissue that occur if someone has multiple sclerosis and it is possible to see changes occurring when there is bleeding in the brain, or find out if the brain tissue has suffered lack of oxygen after a stroke.

 

The MRI scan is also able to show both the heart and the large blood vessels in the surrounding tissue. This makes it possible to detect heart defects that have been building up since birth, as well as changes in the thickness of the muscles around the heart following a heart attack. The method can also be used to examine the joints, spine and sometimes the soft parts of your body such as the liver, kidneys and spleen.

 

How does an MRI scan differ from a CT scan?


With an MRI scan it is possible to take pictures from almost every angle whereas a CT scan only shows pictures horizontally. There is no ionizing radiation (X-rays) involved in producing an MRI scan. MRI scans are generally more detailed, too. The difference between normal and abnormal tissue is often clearer on the MRI scan than on the CT scan.

 

What will I be expected to be able to do after studying this topic?


  • Understand the health and safety considerations to be adhered to by health care professionals when using equipment to take MRI images

  • Describe how an MRI scan is taken and how the images are produced

  • Explain the principles of the MRI technique

  • Analyse MRI images to identify features


What are the key words to learn and use for this topic?


  • Magnetic resonance imaging

  • Magnetic field

  • Magnetic realignment


How long will this topic take to study?


On average you’ll be looking at about one hour of taught time and independent study


What are the main activities on this topic?


Activity


Check out the following links:


Virtual department of the Royal College of radiologists, the department from different perspectives - the radiologist, the patient, the equipment




Video of patient undergoing an MRI scan







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