1 / 11

Revision Magnetism & MRI (difference between magnetic & MRI ) Biophysics (PHR 177)

Revision Magnetism & MRI (difference between magnetic & MRI ) Biophysics (PHR 177). Dr. Eng. Safa Ahmed El- Askary Faculty of Allied Medical Science Pharos University Alexandria. M -AGNETIC R -ESONANCE I -MAGING. Introduction. What is MRI?

senona
Download Presentation

Revision Magnetism & MRI (difference between magnetic & MRI ) Biophysics (PHR 177)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Revision Magnetism & MRI (difference between magnetic & MRI ) Biophysics (PHR 177) Dr. Eng. Safa Ahmed El-Askary Faculty of Allied Medical Science Pharos University Alexandria

  2. M -AGNETICR -ESONANCE I -MAGING

  3. Introduction • What is MRI? • Magnetic resonance imaging (MRI) is a spectroscopic imaging technique used in medical settings to produce images of the inside of the human body. • How Does it Work? • The magnetic resonance imaging is accomplished through the absorption and emission of energy of the radio frequency (RF) range of the electromagnetic spectrum.

  4. MRI USES THE HYDROGEN ATOM • The nucleus contains no neutrons but contains 1 proton • Hydrogen nucleus is a spinning, positively charged particle. • Very abundant in the human body-H20 • Has a large magnetic moment

  5. PRECESSION Precessional path • Due to the influence of B0, the hydrogen nucleus “wobbles” or precesses . • The speed at which hydrogen precesses depends on the strength of B0 and is termed the “precessional frequency”. • The precessional frequency of hydrogen in a 1.5 Tesla magnetic field is 63.86 MHz. B0 Hydrogen nucleus

  6. The Technology NET MAGNETIZATION VECTOR An excess of hydrogen nuclei will line up parallel to B0 and create the NMV of the patient • Energy Absorption: • The MRI machine applies radio frequency (RF) pulse that is specific to hydrogen.

  7. Imaging: • When the RF pulse is turned off the hydrogen protons slowly return to their natural alignment within the magnetic field and release their excess stored energy. This is known as relaxation. • What happens to the released energy? • Released as heat OR • Exchanged and absorbed by other protons OR • Released as Radio Waves.

  8. FARADAY’S LAW OF INDUCTION A changing magnetic field will induce an electrical current in any conducting medium COILS • Used to: • transmit pulses of radiofrequency energy • receive induced voltage - MR SIGNAL • increase image quality by tuning in to one body part at a time

  9. Thank you

More Related