This document introduces the key components of an MRI (magnetic resonance imaging) system. It describes the static magnetic field coils, gradient magnetic field coils, magnetic shim coils, radiofrequency coil, subsystem control computer, data transfer and storage computers, and physiological monitoring equipment that make up an MRI system. It then provides details on static magnetic fields, including that those used in medical imaging are typically between 0.5 and 1.5 Tesla. It discusses permanent and electromagnets, focusing on superconducting magnets which are widely used due to their ability to produce high, homogeneous magnetic fields when kept at very low temperatures. Finally, it describes the purpose of radiofrequency coils and magnetic shim coils in MRI systems.

1. BIOMEDICAL ENGINEERING
SYSTEM
INTRODUCTION OF THE
COMPONENTS OF MRI(MAGNETIC
RESONANCE IMAGING)
Engr Khaleeque Ahmed
2011-BM-28
Sir syed university of engineering &
technology Karachi

2.  Static Magnetic Field Coils
 Gradient Magnetic Field Coils
 Magnetic shim coils
 Radiofrequency Coil
 Subsystem control computer
 Data transfer and storage computers
 Physiological monitoring, stimulus display,
and behavioral recording hardware

4.  Earths magnetic field is 0.3-0.7G (G: Gauss)
 1 Tesla is 10000 G
 Magnets used for imaging mostly between .5
to 1.5 Tesla
 PERMANENT AND ELECTROMAGNET
(SUPERCONDUCTING )
 The field should be homogenous.
Inhomogeniety reduces the signal to noise
ratio ; i.e affects the image quality.

5. Electromagnet:
1. Resistive Magnet: An electrical current is passed through a
loop of wire and generates a magnetic field
2. Superconducting magnets: widely used in MR machines.
Here the current carrying conductor is kept at very low
temperatures called SUPERCONDUCTING TEMPERATURE
(4 Kelvin or -269 Celsius).
At this temperature the conducting material looses its
resistance for electricity. And so produces constan magnetic
fields.
Advantages of superconducting magnets are high magnetic
field strength and excellent magnetic field homogeneity

6.  Its used for the uniform distribution of
magnetic field.

7.  These coils are used to applying RF pulse
,which is received by RF reciever.
 RF pulse received by protons & they misalign
 While magnetic field again align them.

8. Shimming: the process by which an in
homogenous magnetic filed is converted to a
homogenous magnetic filed by electrical as well
as mechanical adjustments.
Shim Coils are such devices used for shimming
of the magnetic field (i.e the STATIC MAGNETIC
FIELDS)

9. THANK YOU…………!!!!