| Ultrasound - Musculoskeletal
What is Ultrasound Imaging of the Musculoskeletal System? Back to Top
Ultrasound,
or sonography, involves the sending of sound waves through the body.
Those sound waves are reflected off the internal organs. The
reflections are then interpreted by special instruments that
subsequently create an image of anatomic parts. No ionizing radiation
(x-ray) is involved in ultrasound imaging.
An ultrasound image is a useful way of examining the musculoskeletal
system of the body to detect problems with muscles, tendons, ligaments,
joints and soft tissue. Ultrasound images are captured in real time, so
they can often show movement, function and anatomy, as well as enable
radiologists to diagnose a variety of conditions and assess damage
after an injury or illness.
What are some common uses of the procedure? Back to Top
Ultrasound
images can be useful in diagnosing tendon tears, such as tears of the
rotator cuff in the shoulder or Achilles tendon in the ankle.
Abnormalities of the muscles, such as tears and soft-tissue masses, can
also be seen. Bleeding or other fluid collections within the muscles,
bursae and joints can also be detected. Ultrasound has not proven
useful in detecting whiplash injuries or other causes of back pain.
How should I prepare for the procedure? Back to Top
You should wear comfortable, loose-fitting clothing for your ultrasound exam. No other preparation is required.
What does the equipment look like? Back to Top
The equipment
consists of a transducer and a monitoring system. The transducer is a
small, hand-held device that resembles a microphone. The radiologist or
sonographer spreads a lubricating gel on the area being examined and
then presses this device firmly against the skin.
The ultrasound image is immediately visible on a nearby screen that
looks much like a computer or television monitor. The radiologist or
sonographer watches this screen during an examination and captures
representative images for storage. Often the patient is able to see it
as well.
How does the procedure work? Back to Top
Ultrasound imaging
is based on the same principles involved in the sonar used by bats,
ships at sea and anglers with fish detectors. As a controlled sound
bounces against objects, its echoing waves can be used to identify how
far away the object is, its shape, how large it is, and its internal
consistency (fluid, solid or mixed).
The ultrasound transducer functions as both a loudspeaker (to create
the sounds) and a microphone (to record them). When the transducer is
pressed against the skin, it directs a stream of inaudible,
high-frequency sound waves into the body. As the sound waves echo from
the body's fluids and tissues, the sensitive microphone in the
transducer records tiny changes in the sound's pitch and direction.
These signature waves 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 can be recorded on videotape. In
addition, still frames of the moving picture are usually "frozen" to
capture a series of images.
How is the procedure performed? Back to Top
The patient is
positioned on an examination table that can tilt and move. A clear gel
is applied to the area that will be examined. Since the sound waves
cannot penetrate air, the gel helps the transducer make a secure
contact and eliminates air pockets between the transducer and the skin.
The radiologist then presses the transducer firmly against the skin and
sweeps it back and forth to image the area of interest, reviewing the
images on the monitor and capturing "snapshots" as required.
When the examination is complete, the patient may be asked to dress
and wait while the ultrasound images are reviewed either on film or on
a monitor. Often though, the sonographer or radiologist is able to
review the ultrasound images in real time as they are acquired and the
patient can be released immediately.
What will I experience during the procedure? Back to Top
Most
ultrasound studies are relatively quick and well-tolerated by the
patient. If scanning is performed over an area of tenderness, there may
be minor pain associated with the procedure. Otherwise the procedure is
painless. You will be either lying or sitting on an examining table
that may be tilted or moved to provide access to the area that will be
imaged. The sonographer or radiologist will spread some gel on your
skin and then press the transducer firmly against your body, moving it
until the desired images are captured. Most exams take 45 minutes or
less.
Who interprets the results and how do I get them? Back to Top
A
radiologist, who is a physician experienced in ultrasound and other
radiology examinations, will analyze the images and send a signed
report with his or her interpretation to the patient's personal
physician. The patient receives ultrasound results from the referring
physician who ordered the test results. New technology also allows for
distribution of diagnostic reports and referral images over the
Internet at some facilities.
What are the benefits vs. risks? Back to Top
Benefits
- Ultrasound scanning is usually painless and noninvasive.
- Ultrasound is widely available and easy to use.
- Ultrasound imaging uses no ionizing radiation.
- Ultrasound
provides real-time imaging, making it a good tool for guiding minimally
invasive procedures such as cortisone injections, needle biopsies and
aspiration of fluid in joints or elsewhere.
- Unlike the
strong magnetic field of magnetic resonance imaging (MRI), ultrasound
is not affected by cardiac pacemakers, ferromagnetic implants or
fragments within the body. Ultrasound is also an excellent alternative
to MRI for claustrophobic patients.
- Ultrasound may
actually have advantages over MRI in seeing tendon structure, which is
better appreciated by ultrasound than MRI.
Risks
- For standard diagnostic ultrasound there are no known harmful effects on humans.
What are the limitations of Ultrasound Imaging of the Musculoskeletal System? Back to Top
Ultrasound
has difficulty penetrating bone and therefore can only see the outer
surface of bony structures and not what lies within and beyond. For
visualizing internal structure of bones or certain joints, other
imaging modalities such as MRI should be selected. Back to Top |
