Magnetic resonance
imaging (MRI)
Clinical Applications
Is used for non-bony part or soft tissues of the body
Brain, spinal cord, nerves, muscles, ligaments and tendons is clearer in MRI image than x-rays and CT
fMRI ( Functional Magnetic Resonance Imaging
Used for observe brain structure and found the brain area that consume more oxygen (activate)
For more understanding of brain organization
Basic Components in MRI 
Basic principles in MRI
Gradient Coils 
Radio Frequency (RF) coils 
Antenna/Computer System 
Placing the patient in the magnet
Sending radiofrequency (RF) pulse by a coil
Receiving signals from the patient by a coil
Transformation of signals into the image
Longitudinal Magnetization
Transverse Magnetization
MRI room set-up
Equipment Room 
Control Room 
Magnet Room 
K-Space and scanning Parameter
Parameter of Scanning
Matrix
Field of View
Number of excitation (Nex)/ Number of signal average (NSA)
Flip angle
Bandwidth
Localization of the Signal
Principles of MRI
History of MRI 
2003
Lauterbur and Peter Mansfield were awarded nobel prize for the MRI development
1977
Peter Mansfield introduced echo-planar imaging
1946
Felix Bloch and Edward Purcell discover magnetic resonance phenomena and awarded nobel prize
1971
Raymond Damadian reveal nuclear magnetic relaxation times of tissues and tumors
Definition
A medical imaging technique that uses a magnetic field and computer-generated radio waves to create detailed images of the organs and tissues in your body
The floor able to support heavy weight, because MRI weight is 4500 kg, 7500 kg
Contrast injectors is included
Window to see patient
Function of walls in magnet room :
magnetic shielding to confine the fringe field
acoustic shielding to restrict noise transmission
RF shielding to prevent electromagnetic noise to go anywhere
Components of the cooling system for the magnet, amplifiers, and gradient coils, including a cryocooler compressor and a heat exchanger.
This is immediately outside the magnet room and contains the operator console, keyboard, communication devices, oxygen monitors, and computer equipment that controls the scanner.
Located immediately adjacent to the Magnet Room, this contains devices that control and support the magnet operation.
The gradient coils create a variable field (x, y, z) that can be increased or decreased to allow specific and different parts of the body to be scanned by altering and adjusting the main magnetic field.
The basic function of the RF coils is to transmit radio frequency waves into the patient's body.
There are three different gradient coils that produce three different magnetic fields, each less strong than the main field.
There are different coils located inside the MRI scanner to transmit waves into different body parts.
The antenna is a sensitive device that detects the RF signals emitted by the patient's body and feeds this information into the computer system
:
Clinical Safety
And also breast feeding women
Pregnant women need to ask the doctor first before MRI
The ink in tattoo or make up sometimes contain metal
Patient need to complete the questionnaire, whether they have metal or electronic device in the body
safety hazard if attracted to the magnet
The computer system receives, records, and analyzes the images of the patient's body that have been scanned, and helps to produce an understandable image.
Three additional magnetic fields (gradient fields) are superimposed on the main magnetic field along the x, y, and z axes to localize the origin of the body's signal.
The gradient fields are produced by gradient coils and are used for slice selection, phase encoding, and frequency encoding.
The protons that align parallel to the B0 field create a net longitudinal magnetization (LM) vector along the positive side of the z-axis.
A 90-degree RF pulse creates an imbalance in the proton forces, resulting in a decrease in LM and an increase in magnetization in the transverse plane, forming a transverse magnetization (TM) vector.
the rage of the frequencies used in the
transmission or reception of an electronic signal
It is the angle by which the LM vector is rotated away
from the z axis by a RF pulse.
It is the area which information is obtained and
represented on the image.
a pixel(picture elements) is the smallest unit in digital
images. Greater size of matrix, better the image resolution.