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Conventional
high field Magnetic Resonance Imaging
systems usually operate at stronger
field strengths than open MRI systems
and typically provide clearer, more
detailed and easier to read scans. On
a high field or closed MRI system, the
slices can be thinner, improving the
information the physician uses to
diagnose the problem.
High field MRI units may also take
less time due to the higher magnetic
field strength. High field scans can
be one and a half to two times faster
than an "open" scan. High
field Magnetic Resonance Imaging
scanners also provide the most
advanced imaging techniques, some of
which cannot be performed on an open
scanner. Many optional accessories are
available.
High field MRI systems are indicated
for central nervous system and
vascular studies - particularly
contrast enhanced Magnetic Resonance
Angiography (MRA) studies, abdominal
work that requires the patient to hold
their breath, fat saturation
techniques, certain cancer studies and
any study that requires the highest
resolution.
Types of scans that should be
performed on a high field scanner
include:
• Temporomandibular joints (TMJ)
• Brain – Sella
• Liver and pancreas
• Non-Brain MRA (i.e. aorta)
• Recent CVA
• Patients in severe pain or who
can’t hold still
Magnetic Resonance Imaging (MRI) is a
method of obtaining detailed pictures
of internal body structures without
the use of radiation or radioactive
substances of any kind. This is
accomplished by placing the patient in
a magnetic field while harmless radio
waves are turned on and off. This
causes the body to emit its own weak
radio signals which vary according to
tissue characteristics. These signals
are then picked up by a sensitive
antenna and fed to a computer which
produces detailed images of the body
for interpretation by trained
radiologists.
High Field MRI utilizes a cylindrical
tube in which the magnet is enclosed.
Patients are placed in the unit lying
down, either head first or feet first.
Since this configuration produces
optimum magnetic field strength, the
signal and images produced are of the
highest quality. HF MRI exams usually
take 20 - 30 minutes.
You can help to produce a high quality
image by lying still during the
examination while breathing normally.
The average scan takes 5 to 15 minutes
- the complete examination about 30 to
45 minutes - during which several
dozen images will be produced.
With incredible accuracy, MRI can
detect many abnormalities which CT
scanning and X-rays cannot, especially
those involving soft tissue. In fact,
MRI reduces the need for biopsies,
exploratory surgery, and other
diagnostic procedures which carry
associated risk.
During the test you will neither see
nor feel anything happen. It is
totally painless and has no known side
effects. Because no radiation or
radioactive substances are used,
patients requiring frequent scans
avoid the potential danger of
cumulative radiation exposure.
Magnetic resonance imaging (MRI) is
used to find problems, such as tumors,
bleeding, injury, blood vessel
problems, or infection. An MRI may be
done using contrast material to see
abnormal tissue clearly. An MRI can be
done for the:
• Head. MRI can look at the
brain for tumors, an aneurysm,
bleeding in the brain, nerve injury,
and other problems, such as damage
caused by a stroke. MRI can also find
problems of the eyes and optic nerves,
and the ears and auditory nerves.
• Chest. An MRI of the chest
can look at the heart, the valves, and
coronary blood vessels. It can show if
the heart or lungs are damaged. MRI of
the chest may also be used to look for
breast or lung cancer.
• Blood vessels. Using an MRI
to look at blood vessels and the flow
of blood through them is called
magnetic resonance angiogram (MRA). It
can find problems of the arteries and
veins, such as an aneurysm, a blocked
blood vessel, or a torn lining of a
blood vessel (dissection). Sometimes contrast
material is used to see the
blood vessels more clearly.
• Abdomen and Pelvis. MRI can
find problems in the organs and
structures in the belly, such as the
liver, gallbladder, pancreas, kidneys,
and bladder. It is used to find
tumors, bleeding, infection, and blockage. In women, it can look at the
uterus and ovaries. In men, it looks
at the prostate.
• Bones and Joints. MRI can
check for problems of the bones and
joints, such as arthritis, problems
with the temporomandibular joint, bone
marrow problems, bone tumors,
cartilage problems, torn ligaments or
tendons, or infection. MRI can also
tell if a bone is broken if an X-ray
cannot. MRI is done more commonly than
other tests to check some bone and
joint problems.
• Spine. MRI can check the
discs and nerves of the spine for
conditions such as spinal stenosis,
disc bulges, and spinal tumors.
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