MRI.pdf

MRI is a type of diagnostic test that can create detailed images of nearly every structure and organ inside the body. MRI uses magnets and radio waves to produce images on a computer. MRI does not use ionizing radiation. Images produced by an MRI scan can show organs, bones, muscles and blood vessels.

1. MRI
The human body consists of about
85% water, which consists of 2
hydrogen and 1 oxygen atom.
" MR imaging is based on proton
imaging. Protons are +ve charged
particles in the nucleus of every atom
and have rotatory movement called
spin.
Any charge, which moves generates
current and every current have a
small magnetic field around it. So
every spinning hydrogen proton have
a small magntic field around it.
In MRI, this small magnetic field of
hydrogen protons are used to
produce diagnostic image.

2. Ro
Midsagittal
Scanning projections
R.L
Parasagita
" Sagittal view : viewing body from
right to left direction.

3. T
Top
Bottom
" Transverse view :
viewing body from
upper and lower
direction.

4. C
Back Front
" Coronal view : viewing
body from anterior and
posterior direction.

5. Equipment used in MRI
1. Gantry:it is a doughnut
shaped device containing the
magnet.
" Magnet : to produce magnetic
field.
" Bore : the empty space in the
middle of the magnet is called
bore and this is where the
patient interact with magnetic
field and reveal diagnostic
information.

6. 2. Patient table:
" The patient table supports the
patient and allows the patient to be
moved into the bore for scanning.
" The table is curved for patient
comfort and also conforms to the
shape of the bore(60 cm).
" It is constructed of non-magnetic
material to avoid altering the
magnetic field (plastic, copper,
aluminium, rubber).
" The table allows the patient to be
raised and lowered to assist the
patient in lying on the table.

7. 3. Computer
" The computer is a major
component in the
formation of MR image.
" It process different signals
from the patient body to
create MR image.
4. Display
" The data can be viewed
into routine transverse,
sagittal and coronal.

8. Procedure
Although ionizing radiation is not used in MRI but still there
are import ant salety consideration sleps ivolved.
1
2.
3.
4.
MRI includes strong rmagnetic filed theretore paticnt
with implants, prostheses (artificial body limb).
aneurysm clips, pacemakei, heart valves, breast
implant, cochlear implant (hearing aid) should be
checked properly betore placing palient MRI room.
Non-metallic implant materials an lead to significant
heating under magnetic field which can lead o
misdiagnosis
Presence of tattoo, mascara, piering should also be
avoided.
Ferro magnelic material brought into the imaging
room 1or eg. IV pole are attraded by magnetic field
and can bECome deadly projectile for the paticnt with
in the bore of the magnet.
After confirmation the patient is asked to lie down on the
examinatian table until the scan is completed.

9. Indication and contraindications
Indications
Torn ligament
" Soft tissue problems
"Spinal problems
" Nerve issues
" Inflammation
Contraindications
" Any non-removable metallic
device.
" Claustrophobia
" Pregnancy (if not emergency
case)

10. " The most common bio-effect of MR system is tissue heating caused by
magnetic field energy deposition.
Metallic taste
" Flushing of face
" Blur vision
MRI Biological Effects
"ECG : change in natural wave form for a short duration.
Disadvantage
"MRI Scans produce loud noises which saome people may find stressful.
" Longer scan time.