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 precess in 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