Download Magnetic Resonance Imaging

Under the supervision of:
Dr.Mohamed Hesham
Prepared by :
Ahmed Mostafa Hassan Elsayed Elsaghier
Is the way medical imaging to illustrate the pathological
changes in living tissue and magnetic resonance non-medical
uses of physical hand they rely on the so-called nuclear
magnetic tone RMN. Magnetic resonance imaging is costly
tests and is permanently available in many hospitals, and
there are difficulties when making this type of radiation in
patients who are afraid of enclosed spaces or patients who
complain of excessive obesity.
MRI :
 Start date and the birth of the idea of magnetic resonance in
year 1945-1946 When won world Felix Bloch & Edward Purcell
the Nobel Prize for his discovery of MRI. Developed by the
world's Erwin Hahn in 1950. Developed for medical use in 1973
at the hands of the British and American worlds Peter
Mansfield & Paul Aoterbr. 1976 published the first picture of a
magnetic resonance toe. And in 1977 published the first full
body imaging. It should be noted that the MRI initially use in
chemical plants only after it has been updated to enter the
medical field. Initially called nuclear magnetic resonance, but
later changed the name to the public fear and sensitive of the
word nuclear was intended by the nucleus of an atom of
nuclear radiation itself.
The idea magnetic resonance :
 The idea MRI to stimulate the protons in the atoms in the
body to launch signal, and then picked up and determine
its location in the body and displayed on a scale of gray
color indicates the signal strength, and gradually be
different tissues in the body.
 More of these elements is hydrogen and stimulation that
he was in abundance in living bodies & the of a single
proton in the atomic nucleus, giving it more power than
the rest of the items on the version of the signals used in
magnetic resonance imaging.
MRI types :
 There are different types and multiple day with many ideas for
magnetic resonance imaging devices, in general, there are three
main types of magnetic resonance :
 Permanent
 Resistant
 And anti-resistance
 -MRI generally contains part gives the strong magnetic field & part
issued radio waves to stimulate the protons and captures the
incoming signal & progressive part of the system.
 -Survey, which is used in the medical cost areas million per Tesla and
several hundreds of thousands of dollars are spent annually in
maintenance. - Used computers mainly in MRI scans and advanced
programs effectively help to give the best results.
Magnetic Resonance Physics :
 The device consists of an electromagnet coil huge for the formation of a
magnetic field around the patient produces a magnetic field 2 Tesla
equivalent to 20,000 Gauss .
 -This area makes hydrogen atoms Taatmgnt all tend to its magnetic north
Vtaatouhd part in one direction. After piece displays the body to radiation
Mveaih lead to increased energy these atoms and piece will change its
direction to a certain degree, leaving us an atom of every million corn is the
process of magnetic resonance imaging, a large number of atoms enough for
the emergence of a clear picture of you very much to be photographed and
sent a couple of energy reverse. This inverse receive energy from the device
are calculated and composed in the form of a photo This picture shows the
intensity of hydrogen in every region of the body. Using this image doctors
can discover a lot of diseases.
 the emergence of a clear picture of you very much to
be photographed and sent a couple of energy reverse.
This inverse receive energy from the device are
calculated and composed in the form of a photo This
picture shows the intensity of hydrogen in every region
of the body. Using this image doctors can discover a lot
of diseases.
 -When provoked atoms in the body are protons
movement with & against the direction of the
magnetic field the main, getting protons approval to
the direction of the main for protons anti small
amounts but very important to get the picture later,
and disturbed these protons, especially radio waves
Climate of set of vertical to horizontal, but What soon
return to equilibrium mode, but to return to
equilibrium situation there important Toukatan.
 Time horizontal
 Time the fastest time in the horizontal is the scattering of protons
on the horizontal axis.
 Time vertical
 Time vertical a time when protons return to equilibrium mode
 -It should be noted that Altoqatn occur concurrently to each other.
 -Measured energy magnets used in magnetic resonance imaging
unit tesla is equal to 10,000 Gauss, measuring the earth's average
magnetic found to be equal to half Gauss.
 Proton density
 -The number of active protons per unit volume of tissue, and vary the
density of the fabric to another fabric .
 Echo cycle

-After the
impact of protons by radio waves are broadcast waves again it goes
back 180 °, and measured the length of time between the first 90 ° impact
and influence, 180 ° Time echo.
Echo cycle
-After the impact of protons by radio waves are
broadcast waves again it goes back 180 °, and
measured the length of time between the first 90 °
impact and influence, 180 ° Time
MRI uses :
 Using magnetic resonance diagnostic is for the purpose of
such imaging veins and arteries, or filming neurological
changes in the brain, and magnetic resonance imaging is
considered the best types to clarify the tissues and body
fluids, as well as used to plan treatment plans based on
radiation therapy. By magnetic resonance medical history
should be reviewed fully and make sure there is no
previous surgery or accidents led to the presence of metals
in the body, such as shrapnel, and be sure that the crossscan routine & passage of the patient through the metal
detector. Often gives the patient a special dye is injected
into the body so as to increase the contrast and clarify parts
converged.
Magnetic resonance image :
 Composed image magnetic resonance of several columns and
rows called another question matrix, each column description
contains the boxes called pixel, distributes signals captured from
the body on these boxes so arranged as arranged in the body, and
this mechanism relies on a graded gives each segment of the
body force specific signal, and the signal strength captured give
color to grayscale, consists us a picture of magnetic resonance
image gray gradient. - Private equation clarity is:
 Number of boxes per cm = 1 / size of the box
 -The contrast in the image depends on the vertical and
horizontal times and proton density and called (internal
influences), and the echo time and repetition oukt considered
(externalities.
Definition (IMAGE RESOLUTION)
 More MRIs consists of two dimensions, each divided
into a network of sham rectangular elements called
(pixels) pixels.
 Intensity in each pixel depends on the strength of the
magnetic resonance wave emitted from the region that
they contain.
 Image size depends on the number Baksalat, and Most
images consisting of 265 Pixels vertically and 256
horizontally Pixels.
Definition clarity (image resolution):
 is the system's ability to distinguish between two separate








points .
Control sizes Alfoxlat (volumetric picture elements) (voxels) in
clarifying the image (image resolution) as the small-Alfoxlat
images be good evacuation and thus make it easier for the system
to differentiate between small body components .
-Factors affecting the evacuation and size Alfoxl :
Thickness of the slide.
Field of view FOV.
Matrix moot .
-Factors that control the supply and field dimensions Alfoxl :
The strength of the magnetic field out.
Time taken for each sample (bandwidth) for the progressive
field.
Contrast (CONTRAST) :
 Signal strength klmazadt from pixel greater the




brightness of the image at that pixel .
To distinguish between tissues in the picture, every
tissue has a different brightness These Aldahirh called
mixed .
And can be divided into the factors affecting the
variance into two groups .
Internal factors: a change stromal factors .
Proton density PD .
 Longitudinal relaxation T1 :
 Transverse relaxation T2 :
 External factors: These are factors that can be changed by
the operator :
 Repetition time TR .
 Time of excitement TE .
 And change the power of the wave with the changing
weights multiplied by three, namely :
 Proton density.
 T1 weighted: a guest T1 and TR .
 Weighted T2: a guest T2 and TE .
 This relationship can be represented in the following
equation :
Signal = (p (H) [1-exp (-TR/T1)] × [exp (-TE/T2[(
 We can deduce from the equation that we can change the
contrast by changing one of the external factors :
 For example: if we want weighted density proton must
finish effect weights other T1 and T2 and we did it change
in external factors, if we are weighted T1 must all be from
the time of recurrence and time thrills short, and if we are
weighted T2 must be Taiwilan, if we are likely proton
density must be a long time repetition and thrills short
time .
Safety in the Magnetic Resonance
 No, as is the case in CT imaging




and general risk ionization
radiation, but no magnetic
resonance as is the case in all the
use of certain medical risks .
Risk magnetization metals and
grabbed the device .
Loud sounds produced during the
test .
Claustrophobia .
A helium leak in the ultra Delivery.
Index :
Magnetic Resonance Imaging
2
History
3
MRI types
5
Magnetic Resonance Physics
6
MRI uses
11
Safety in the Magnetic Resonance
20
References :
 Physics Serway .
 http://ar.wikipedia.org .
I hope to be able to benefit the reader