ULTRASONOGRAPHY

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ULTRASONOGRAPHY
DR MANOJ ABHANG MD PART II
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• INTRODUCTION
• 1) Debut in 1950 but application remain confined
  until grey scale ultrasonography
• 2) Ultrasound imaging, also called ultrasound
  scanning sonography, involves exposing part of
  the body to high-frequency sound waves to produce
  pictures of the inside
• of the body.
• 3) Ultrasound exams do not use ionizing radiation
  (x-ray).
• 4) Ultrasound images are captured in real-time,
  they can show
• the structure and movement of the body's
  internal organs,
• as well as blood flowing through blood
  vessels.
• 5) Ultrasound imaging is usually a painless
  medical test that helps physicians diagnose and
  treat medical conditions.

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• 5) Conventional ultrasound displays the images in
  thin, flat
• sections of the body.
• 6) Advancements in ultrasound technology include
  three-
• dimensional (3-D) ultrasound that formats
  the sound wave
• data into 3-D images.
• Four-dimensional (4-D) ultrasound is 3-D
  ultrasound in
• motion.
• 8) A Doppler ultrasound study may be part of an
  ultrasound examination.

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B) EQUIPMENT - 1) Ultrasound scanners consist
of a console containing a computer and
electronics, a video display screen and a
transducer that is used to scan the body. 2)
The transducer is a small hand-held device that
resembles a microphone, attached to the
scanner by a cord. 3) The transducer sends out
a high frequency sound wave and then
listens for a returning sound wave or "echo."
4) The ultrasound image is immediately visible
on a nearby screen that looks much like a
computer or television monitor. 5) The image is
created based on the amplitude (strength),
frequency and time it takes for the sound signal
to return from the patient to the
transducer.
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6) Displays - a) A-scan (amplitude
modulation) echoes recorded
in vertical deflections of the spot b) B
scan (brightness modulation)
bright dotes along the base line of cathode ray
oscilloscope c) Time position (M mode)
almost entirely in
echocardiography d) Real time display
Dynamic display instead of static
pictures Rapid series of
static images rate of change 40 frames/min
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7) Types of probes- a) Linear held
vertically, most detailed accurate detail,
except in few
inaccessible areas like pelvis b) Sector
a wedge of tissue is examined with apex of
tissue, useful in
pelvis, subcostal regions c) Arc similar
to linear but movment to skin is different
d) Compound complex combination of above
e) Radial Probe rotate around fixed point,
intracavitary
examination like transvaginal scanning 8)
Commonest substance used in medical ultrasonics
is LEAD ZIRCONATE
TITANATE
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C) WORKING OF USG - 1) Ultrasound imaging is
based on the same principles involved in
the sonar used by bats, ships and fishermen. 2)
When a sound wave strikes an object, it bounces
backward, or echoes. 3) By measuring
these echo waves it is possible to determine
how far away the object is and its size, shape,
consistency (whether the object is solid,
filled with fluid, or both) and
uniformity. 4) In an ultrasound examination, a
transducer both sends the sound waves
and records the echoing waves. 5) When the
transducer is pressed against the skin, it
directs a stream of inaudible,
high-frequency sound waves into the body.
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6) As the sound waves bounce off of internal
organs, fluids and tissues, the sensitive
microphone in the transducer records tiny
changes in the sound's pitch and direction. 7)
These signature waves are instantly measured and
displayed by a computer, which in turn
creates a real-time picture on the monitor.
8) These live images are usually recorded on
videotape and one or more frames of the
moving pictures are typically captured as
still images. 9) Pentrancy decreases as
frequency increases - High frequency beam
will be able to image only superficial
structures - Balance between pentrancy
details - Abdominal imaging 2.5 or 3 Mhz
- Scrotum or intraopertaive probes 10 Mhz
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D) PROCEDURE OF USG - 1) For most ultrasound
exams, the patient is positioned lying
face-up on an examination table that can be
tilted or moved. 2) A clear gel is applied to
the area of the body being studied to
help the transducer make secure contact with the
body and eliminate air pockets between the
transducer and the skin. 3) The sonographer
(ultrasound technologist) or radiologist then
presses the transducer firmly against the
skin and sweeps it back and forth over the
area of interest.
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4) In some ultrasound studies, the transducer is
attached to a probe and inserted into a
natural opening in the body. These exams
include - Transesophageal echocardiogram.
The transducer is inserted into the
esophagus to obtain images of the heart. -
Transrectal ultrasound. The transducer is
inserted into a man's rectum to view the
prostate. - Transvaginal ultrasound. The
transducer is inserted into a woman's
vagina to view the uterus and ovaries.
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E) COMMON USES - Ultrasound is a useful way of
examining many of the body's internal organs,
including but not limited to the 1) Heart and
blood vessels, including the abdominal aorta and
its major branches 2) Liver 3)
Gallbladder 4) Spleen 5) Pancreas 6)
Kidneys 7) Urinary bladder 8) Uterus, 9)
Ovaries, and unborn child (fetus) in pregnant
patients 10) Eyes 11) Thyroid and parathyroid
glands 12) Scrotum (testicles)
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Ultrasound is also used to 1) Guide procedures
such as needle biopsies, in which needles
are used to extract sample cells from an abnormal
area for laboratory testing. 2) Image
the breasts and to guide biopsy of breast cancer
3) Diagnose a variety of heart conditions
and to assess damage after a heart attack
or other illness.
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COMPARATIVE ESTIMATE OF USG, MRI, CT SCAN
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EXCELLENT ABOVE AVERAGE
SATISFACTORY
/- UNSATISFACTORY -
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Ultrasound Gallbladder
                                  
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Ultrasound Kidney                               
    
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Ultrasound Liver                                
   
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• F) Benefits
• Ultrasound scanning is noninvasive (no needles or
  injections)
• and is usually painless.
• 2) Ultrasound is widely available, easy-to-use
  and less expensive than other imaging methods.
• 3) Ultrasound imaging uses no ionizing
  radiation.
• 4) Ultrasound scanning gives a clear picture of
  soft tissues that do not show up well on x-ray
  images.
• 5) Ultrasound causes no health problems and may
  be repeated as often as is necessary if medically
  indicated.
• 6) Ultrasound is the preferred imaging modality
  for the diagnosis and monitoring of pregnant
  women and their unborn infants.
• .

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6) Ultrasound provides real-time imaging, making
it a good tool for guiding minimally
invasive procedures such as needle biopsies
and needle aspiration of fluid in joints or
elsewhere. Risks For
standard diagnostic ultrasound there are no known
harmful effects
on humans.
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G) LIMITATION - 1) Ultrasound waves are
reflected by air or gas therefore
ultrasound is not an ideal imaging technique for
the bowel. Barium exams and CT scanning are
the methods of choice for bowel-related
problems. 2) Ultrasound waves do not pass
through air therefore an evaluation of the
stomach, small intestine and large intestine
may be limited. 3) Intestinal gas may also
prevent visualization of deeper structures
such as the pancreas and aorta. 4) Patients who
are obese are more difficult to image because
tissue attenuates (weakens) the sound waves as
they pass deeper into the body.
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5) Ultrasound has difficulty penetrating bone and
therefore can only see the outer surface
of bony structures and not what lies
within. For visualizing internal structure of
bones or certain joints, other imaging
modalities such as MRI are typically used.