MRIMagnetic resonance imaging

Definition

• NMR = Nuclear Magnetic Resonance

• MRI = Magnetic Resonance Imaging

• ESR = Electron Spin Resonance

Similarity

• Basic principles• while in the magnetic field, radio waves redirect

the axes of spinning nuclei or electrons

Continue Similarity

• Electron magnetic radiation is used to flip the alignment of nuclear or electron spin

• from low energy spin aligned state to high energy spin opposed state

• Radio frequency is absorbed, that is what is measured

Difference

• MRI: spin of nuclei of an odd mass or odd atomic number (usually H)

• ESR: spin of electrons of most fundamental particles

• ESR: particles will do as many as possible to pair up electrons

• MRI: nuclei also do, but not that many

Applications

• MRI is used for body examination.

• MRI can help in visualizing the human body. It can form structure images of tissues and bones in high definition.

• Also, they can detect problems such as tumors and gores.

Basic MRI scans

T2 Weighting

T2* Weighting

FLAIR

T1 Weighting with gadolinium

contrast

• T1,T2 are the time constant values.

• they determine the physical property changes of a specific tissue when it receives a series of radial pulse from the machine .

• Different type of tissue may have different T1, T2 values. This is due to the difference in behaviors of the H’s protons in a particular tissue when a radial pulse is transmitted to it by the magnetic field.

• Images that contains both the T1,T2 properties can be formed by adjusting TR,TE variables.

Uses in medical field

Backbone

Head Knee and muscles

Heart Liver

Liver CancerKidney

Side Effect of MRI

• MRI Side-effects are mostly temporary effects. The MRI scan itself does not usually have any physical side-effects.

• Projectile or missile effect

• Peripheral nerve stimulation (PNS)

• Radio frequency energy

• Acoustic noise• Contrast agents

Politics Issue

• Our government is investing money on MRI technology to solve following problems

1. Wait List

2. Side Effect

3. Cost

Work cites• http://www.magnet.fsu.edu/usershub/scientificdivisions/emr/overview.html• http://www.chem.ucalgary.ca/courses/351/Carey/Ch13/ch13-nmr-1.html• http://www.radiologyinfo.org/en/info.cfm?pg=bodymr#part_five• http://www.chinamedi.cn/bbs/dispbbs.asp?boardID=17&ID=160&page=5• http://answers.yahoo.com/question/index?qid=20060902235859AAjZ7gx

• Simon, Merrill; Mattson, James S (1996). The pioneers of NMR and magnetic resonance in medicine: the story of MRI. Ramat Gan, Israel: Bar-Ilan University Press. ISBN 0-9619243-1-4.

• Haacke, E Mark; Brown, Robert F; Thompson, Michael; Venkatesan, Ramesh (1999). Magnetic resonance imaging: physical principles and sequence design. New York: J. Wiley & Sons. ISBN 0-471-35128-8.

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