mri presentation main

Directed by:Dr/ waled el atbaniPresented by:Karim’s group

IntroductionTypesUsesThe ComponentsPrinciple of the MRIHow does MRI worksAdvantages & DisadvantagesReferences

MRI is a technique in radiology which uses magnetism, radio waves and a computer to produce images of body structures.

Human body is mainly composed of fat and water, which makes the human body composed of about 63% hydrogen

Why Are Protons Important to MRI? ◦positively charged. ◦spin about a central axis.◦ a moving (spinning) charge creates a magnetic field.◦the straight arrow (vector) indicates the direction of the

magnetic field.

MRI scans are used as an extremely accurate method of detecting disease throughout the body. Head trauma, Brain Aneurysms, Stroke, Tumors of the brain, and Spine tumors, are all abnormalities that are detected by a MRI scan.

A magnet which produces a very powerful uniform magnetic field.

Gradient Magnets which are much lower in strength.

RF Coils to transmit radio frequency.

A very powerful computer system, which translates the signals transmitted by the coils.

The most important component of the MRI scanner is the magnet:

◦The magnets currently used in scanners today are in the 0.5 T to 2.0 T range (5,000 to 20,000-gauss).

Higher values are used for research(up to 9T.

◦While Earth magnetic field: 0.5-gauss

These magnets have a much lower magnetic field and are used to create a variable field.

Transmition of radio frequency.

Spinning Atoms (hydrogen) face outside magnetic fieldEnergy Absorption by RF Coils . Resonance of Hydrogen atoms Measured by RF antenna

which the received signal is sinusoidal in shape. Imaging by The computer which receives mathematical

data, which is converted through the use of a Fourier transform into an image.

1. Put subject in big magnetic field.2. Transmit radio waves into subjects. 3. Receive radio waves that has been re-transmitted by the

subject.4. Store the data &repeat step 2.5. Process raw data to reconstruct images.6. Getting high resolution image.

When placed in a large magnetic field, hydrogen atoms have a strong tendency to align in the direction of the magnetic filed

Inside the bore of the scanner, the magnetic field runs down the center of the tube in which the patient is placed, so the hydrogen protons will line up in either the direction of the feet or the head.

The majority will cancel each other, but the net number of protons is sufficient to produce an image.

provide very detailed diagnostic pictures of most of the important organs and tissues in your body

Ability to diagnose, visualize, and evaluate various illnesses.

are generally painless Did not use radiation and are therefore suitable for

use in children and pregnant women.

Limited availability. It is a lengthy procedure “eg, a pituitary gland MRI

scan can take up to 30 minutes”. MRI scanning cannot be performed in the presence of

foreign bodies or metallic implants “eg, pacemakers”. It is relatively expensive compared with other forms of

imaging.

http://www.nps.org.au/medical-tests/medical-imaging/for-individuals/types-of-imaging/mri-magnetic-resonance-imaging/for-individuals/risks-and-benefits

http://www.webmd.boots.com/a-to-z-guides/tc/magnetic-resonance-imaging-scan-advantages-and-disadvantages

Presentation about MRI Presented by Salwa Aziz & Christina Derbidge

Thanks

Karim yousry basiony Mahmoud ramadan galal Abdel Rahman mohammed gabr Basem ahmed mohammed