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FAQs MRI
| FAQs CT
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FAQs Bone
Density |
FAQ
Ultrasound 
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What is ultrasound? |
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Ultrasound (US),
also called sonography, is a
method of dynamically imaging
the human body through the use
of high-frequency sound waves. A
microphone-like instrument
(transducer) is scanned over the
skin. Gel is placed on the skin
to improve the contact of the
transducer to the area being
examined. The sound waves are
recorded and displayed as a
real-time visual image. US can
be used to examine many parts of
the body including the abdomen,
pelvis and blood vessels, as
well as the fetus during
pregnancy. Because no ionizing
radiation (x-ray) is involved,
ultrasound is an extremely safe
imaging modality. The procedure
is painless and generally takes
about 30 to 45 minutes to
complete. |
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How does the procedure work? |
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Ultrasound
imaging is based on the same
principles involved in the sonar
used by bats or ships at sea. As
the sound passes through the
body, echoes are produced that
can be used to identify how far
away an object is, how large it
is, its shape and its
consistency (fluid, solid or
mixed). The ultrasound
transducer functions as both a
generator of sound (like a
speaker) and a detector (like a
microphone). When the transducer
is pressed against the skin it
directs inaudible,
high-frequency sound waves into
the body. As the sound echoes
from the body’s fluids and
tissues the transducer records
the strength and character of
the reflected waves. These
echoes are instantly measured
and displayed by a computer,
which in turn creates a
real-time picture on the
monitor. The "live" images of
the examination are usually
recorded on videotape but one or
more frames of the moving
picture may be "frozen" to
capture a still image. |
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What are the common uses of
this procedure? |
As a diagnostic
tool, ultrasound has a wide
variety of uses in medicine,
including:
 | Imaging
of veins and arteries to see
and evaluate blockages to
blood flow |
| Examining
many of the body's internal
organs, including the heart,
liver, gallbladder, spleen,
pancreas, kidneys and
bladder |
| Examining
the neck to help diagnose
thyroid abnormalities
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Monitoring fetal development
and accessing fetal
abnormalities |
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Determining the cause of
pelvic pain, abnormal
bleeding and other menstrual
problems |
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Investigating uterine
abnormalities in women who
experience infertility or
multiple miscarriages
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| Imaging
the breast and to guide
biopsy in breast cancer
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Evaluating the prostate
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Determining the source of
pain, swelling or infection
in many parts of the body
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| Assessing
organ damage following
illness |
| Revealing
the shape, texture and
composition of tumors and
cysts |
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What are the benefits of
ultrasound? |
Ultrasound
imaging offers these benefits:
| Provides
a simple, painless and
noninvasive imaging method
for viewing structures
within the body |
| Uses no
ionizing radiation (x-rays)
and is the preferred image
modality for diagnosis and
monitoring of pregnant women
and their unborn infants
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| Produces
real-time imaging, making it
a good tool for guiding
minimally invasive
procedures such as needle
biopsies |
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Visualizes structure,
movement and live function
in the body's organs and
blood vessels |
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What are the limitations of
ultrasound imaging? |
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Ultrasound has
difficulty penetrating bone and
therefore can only see the outer
surface of bony structures and
not what lies within. For
visualization of bone, other
imaging modalities such as
magnetic resonance imaging (MRI)
may be selected. Because
ultrasound waves do not pass
through air, an evaluation of
the stomach, small intestine and
large intestine may be limited.
Intestinal gas may also prevent
visualization of deeper
structures such as the pancreas
and aorta. Obese patients are
also more difficult to image
because tissue attenuates
(weakens) the sound waves as
they pass deeper into the body. |
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