Magnetic Resonance Imaging [MRI]

1. Magnetic Resonance Imaging [MRI] Neju Mathew Philip Inspire Fellow Optoelectronic Materials & Devices Lab NITT

2. OVERVIEW • Introduction • Theory • Instrumentation &Working • Applications • Review

3. INTRODUCTION • Invented by Raymond V Damadian, 1969 • Uses magnetism to produce images of body • Based on the principle of NMR • Paul Lauterbur and Peter Mansfield -Nobel for medicine, 2003

4. THEORY • Body is composed of 60% water • MRI uses the proton in Hydrogen atom • Protons align parallel or anti-parallel in external magnetic field B0 • Precession motion of protons • Larmour frequency ω = γB0

5. INSTRUMENTATION & WORKING • Components • 1. Primary magnet • 2. Gradient magnet • 3. Radio frequency coils • 4. Computer system • Room shielded from • EM rays and metallic objects • Non ionising radiations

6. Protons are aligned parallel or anti-parallel in external magnetic field. • RF coil induces same frequency as of precession. • Resonance effect • All nuclei precessin phase and will go to higher energy state. • Relaxation time for different tissues is different; It defines contrast of the image • Approximate time for scanning – 30 min

7. APPLICATIONS • Can be used to image soft tissues and organs • Widely used to image tumour cells • To detect diseases affecting central nervous systems, spine and brain • Doesn’t use ionising radiation • No after effects • DISADVANTAGES • Room should be shielded from EM interference • Patients with surgical pins, pace makers, etc. cannot undergo MRI • Expensive

8. REVIEW • Uses magnetism to image soft cells and diagnose diseases • Spin of protons • Relaxation time • Advantages & Disadvantages