Basics of ultrasound and duplex

1. ‫الرحيم‬ ‫الرحمن‬ ‫هللا‬ ‫بسم‬
‫العظيم‬ ‫هللا‬ ‫صدق‬

2. By
Dr. MOHAMED ABDEL AZIZ

4. Humans can hear sound with
frequencies of 20 to 20,000
cycles per second (Hertz or
Hz).
Any frequency higher than
that is called ULTRASOUND

5. Ultrasound is diagnostically
useful in medicine in two
modalities, continuous
energy and pulsed energy:
Continuous sound energy
uses a steady sound
source & has applications
that include fetal heart beat
detectors & monitors.

6. Pulsed sound energy utilizes a
quick blip of sound (like a hand
clap), followed by a relatively
long pause, during which time
an echo has a chance to bounce
off the target and return to the
transducer.
.

7. If we could accurately measure the time it
took from handclap to the time we heard
the returning echo, we could calculate
how far the sound has traveled, and by
inference, how far away the wall is from
source of sound.
distance = (time) x (speed of sound in air)
The distance traveled by the sound is
twice the distance to the wall as the
sound had to travel out to the wall and
then back to you (a round trip).

8. Physics:
Ultrasound is a form of mechanical energy that
behaves according to the properties of wave-
form physics. So, terminology of wave-form
physics is usually applied, including wave
amplitude and cycle frequency.
The sonic energy is not identical to electro-
magnetic radiation and while they share some
of the same properties, sound can behave
differently, particularly at extreme ends of the
spectrum, when passing through complex
media. •
•

9. Physiology:
Ultrasound or ultrasonography is a medical
imaging technique that uses high
frequency sound waves and their echoes.
It is used to form an image of organs or
tissue inside the body non-invasively.
The technique is similar to the echolocation
used by bats, whales and dolphins.
Ultrasound is also used as a physiotherapy
treatment where the sound waves are
used to warm muscle tissue deep inside
the body.

10. THE PROBE
The heart of the transducer is the piezoelectric
ceramic crystal which is either natural or
man made.
It has been processed to have the piezoelectric
property of changing the electrical current to
mechanical sound and vice versa.
Piezoelectric means pressure electricity.
The crystal can be thought of as having many
small particles called dipoles. Each dipole
has a positive and negative charge.

11. Behind the crystal is backing material which
dampens the sound pulse.
In front of the crystal is an acoustical lens
which helps to focus and cut down on the
reflections of returning sound impulses.
Probes producing high frequency sound waves
are less penetrating so used for imaging
superficial organs.
Probes producing low frequency sound waves
are more penetrating so used for imaging
deep organs.
Probes are available
in the convex, linear
& endo-cavitary forms.

12. How ultrasound
equipment works?
and
How are sound &
image produced?

14. • First, The generator, or pulser, sends
an electric pulse in a pulsed
(alternating) rather than continuous
pattern to the transducer which
vibrates at a resonant frequency &
changes it into a sound pulse.
• The operator uses the probe or the
transducer to locate the organ or
medical problem by pressing it against
the body or inserting it into an orifice.

15. • The sound pulse travels directly from
the transducer into the body through a
lubricant (jelly), such as mineral oil, that
provides a good connection between the
transducer and the body & removes any
air pockets or bubbles as air acts as a
sound barrier and would result in poorer
resolution.
• The resulting vibration or sound waves
are transmitted into the tissue in short
bursts.

16. • The speed of transmission within most
soft tissues is 1540 m/s, producing a
transit time of 6.5 micro seconds/cm.
• Because the velocity of ultrasound
waves is constant, the time taken for
the wave to return to the probe can be
used to determine the depth of the
object causing the reflection.
• When the waves encounter a boundary
between two tissues of different
density (such as soft tissue and bone)
some will be reflected and return to the
probe.

17. • If the difference is great, a large part of
the sound will be reflected back.
• The imaging, therefore, will be poor
because not enough sound left to be
able to penetrate further and continue
imaging.
• If the difference is small, a small
amount will be reflected back which
would allow enough sound left to
continue through for further imaging.
• It assumes that the wave or beam is
perpendicular to the tissue

18. • Then, the transducer receives the feedback
waves and acts as a receiver, converting
mechanical energy back into an electric signal
which is used to display a two-dimensional
image based on the speed at which the echoes
return on a video monitor.
• The operator can adjust various characteristics
of the image, take measurements, and record the
images for later examination.
• - The most common options are to display it in A-
mode, B-mode, Compounded B-mode, M-mode
or Real-Time mode & we’ll see their meaning.

19. Velocity of Sound in Various Materials
Material Velocity (m/s)
• air 331 -fat 1450
• water (50°C) 1540 -brain 1541
• liver 1549 -human soft tissue 1540
• kidney 1561 -blood 1570
• muscle 1585 -lens of eye 1620
• skull-bone 4080 -brass 4490
• aluminum 6400

20. If the ultrasound beam meets a
rough surface or small object the
beam is scattered in all
directions and only a small
amount will be received by the
probe.
Air within the bowel also scatters
ultrasound, and this is one of the
main causes of non-diagnostic
scans of the abdomen

21. A-Mode Ultrasound
Amplitude is the maximum height that occurs
in a wave minus its normal value. It is
measured in watts (W) and microwatts (µ W).
Amplitude is important in determining the
display and attenuation, the energy loss as
sound travels through a tissue
Intensity is a magnitude, such as energy or a
force, divided by a unit of area, volume, etc.
For sound it is the power, the amount of
energy transferred measured in watts (W)
divided by the area of the sound beam
measured in square meters, (W/m2).

22. Amplitude and intensity
describe the strength of
a sound beam .
The period of a wave
is the time it takes for
one complete cycle to
occur, measured in
seconds(s) or
microseconds (us).
It is the reciprocal of
frequency.

23. B-Mode (Brightness mode) Ultrasound Imaging
B-Mode ultrasound imaging collects the same
information, but adds a sense of direction (where
the echo is coming from in a two-dimensional
plane) as well as the memory to recall all the
different echoes, strong and weak.
This image becomes recognizable with practice.
The recognizable image can then be evaluated for
abnormalities, and measured.
B-mode imaging was the first practical application
of ultrasound for diagnostic purposes.

24. M-mode (or motion mode):
It basically took a B-mode image, turned
it vertically and recorded the returning
images over time.
For example, if the probe was scanning a
particular part of the heart it would
receive the image in B-mode from that
part, but the focus wouldn’t move to
another part of the heart.

26. Real Time Imaging:
The ability to appreciate the structures
within a two-dimensional image is very
much enhanced by visualizing the
changes that occur within that image
over time .
A real-time image is still a 2-dimensional
view, but with time factor becomes 3-
dimensional imaging (height, width,
and time(

27. Four-dimensional ultrasound:
It allows medical professionals
to move the images around
on the monitor in real time
and provide more vibrant
images of the organ or the
body part (as in case of fetal
imaging).

28. Doppler Ultrasound
The Doppler Principle is easiest
illustrated by listening to a train
approaching. As it gets closer,
you hear the horn at a certain
pitch (frequency). As the train
passes, you hear the sound of
the horn drop to a lower pitch.

29. We can consider an object that
generates a sound.
At rest, the sound frequency is
constant.
If the object moves towards you, the
sound that you hear will seem a
little higher in frequency.
If the object moves away from you,
the sound will have a lower
frequency

30. In Doppler imaging it depends on the
fact that if the reflecting surface is
moving in relation to the probe (for
example, blood flowing in a vessel)
the frequency of the received
ultrasound wave will be different from
that of the transmitted wave.
If the reflector is moving towards the
transmitting probe the frequency will
be increased and vice versa.

31. There is a constant relation between this
change in frequency and the velocity of
the moving reflector, and this can be
used to calculate the velocity of flow
within vessels.
For example, in carotid arteries the
velocity of flow increases with the
severity of stenosis.
Ultrasonography can therefore pick up
critical stenoses which require surgery
and display the site of the stenosis at
the same time.

32. Pulsed Ultrasound
If you clap your hands in a large,
empty room, you may hear the echo
from the sound of the clap bouncing
off the far wall and returning to you,
pulsed U/S uses this technique.

33. Structure Appearance:
• Artery: Hypoechoic pulsatile non-
compressible
Doppler… pulsatile flow
• Vein: Hypoechoic non-pulsatile
compressible, Valsalva effect
Doppler… continuous flow
• Muscle: Hypoechoic with multiple
hyperechoic lines
• Tendon: Hyperechoic with bright lines
longitudinally or bright dots at right angles,
fibrillary pattern
• Nerve: Variable hypo- or hyperechoic with
anisotropy fascicular pattern
• Bone: Hyperechoic

34. Advantages
and
Problems

35. Advantages of ultrasonography
• No ionising radiation
• Safe in pregnancy
• No known side effects
• Cheap
• Portable
• Minimal preparation of patients
• Painless
• Non-invasive
• Differentiation between solid & cystic lesions
• Direct vision for biopsy

36. Some problems with U/S examination:
-The patients' build (in obese or kyphotic
patients) or because of excessive bowel
gas scattering the ultrasound beam.
Such patients may require CT imaging.
-Ultrasonography is the most operator
dependent of all types of imaging in
radiology, so may need experienced
operator.

37. Very little patient preparation is required.
Patients must fast before examination of
the abdomen to ensure that the gall
bladder is full and therefore visible.
A full urinary bladder is required before
examination of the pelvis to allow the
prostate or uterus & ovaries to be seen
clearly.

38. Applications

39. OBSTETRIC ULTRASONOGRAPHY
In early pregnancy it is used to confirm intrauterine and
exclude ectopic pregnancy. It can detect a viable fetus
from seven weeks' gestation and transvaginal probes
will detect a fetus even earlier. Missed abortions &
retained products after examinations can be identified.
In later pregnancy it is used to assess growth and to
exclude anomalies such as renal abnormalities,
diaphragmatic hernias, neural tube defects, and
congenital heart defects.
Ultrasound guided antenatal
interventions are also increasing,
Including amniocentesis,
chorionic villus biopsy &
intrauterine fetal transfusion

40. ABDOMINAL ULTRASONOGRAPHY
It is the initial investigation in cases of abdominal pain or
mass, used in identifying & tapping ascites, evaluating
masses for biopsy. It can localise collections in cases of
sepsis, and drains can be inserted into subphrenic,
subhepatic, and pelvic collections.
Its role in the acute abdomen is less well defined.
In equivocal cases of appendicitis, it may show an appendix
mass, stone, or a focal collection of free fluid next to the
appendix. Acute cholecystitis & intussusception can also
be diagnosed.
In Jaundice – It can detect gall stones and determine the level
& cause of bile duct obstruction. Cirrhosis of liver,
splenomegaly, varices, and portal hypertension (seen as
reversed flow or thrombosis in the portal vein) with Doppler
ultrasonography.
Pancreatitis - It is used to exclude gall stones & complications
such as pancreatic abscess or pseudocyst. Large fluid
collections or pseudocysts can be drained at the same time

42. URINARY TRACT:
Used in conditions such as
haematuria, possible renal
mass, and bladder outflow
obstruction due to enlarged
prostate.
Transrectal ultrasonography
and biopsy in patients with
prostatic malignancy.
Prostate volume can be
estimated & correlated with
serum concentrations of PSA
to calculate the likelihood of
malignancy.

43. CHEST
Ultrasonography is not particularly
useful in the lungs because air causes
a great artifact.
It is used, however, to locate and drain
small effusions in pleural disease.
Solid components within the pleura can
be distinguished from loculated fluid
and biopsy specimens taken under
ultrasound guidance .

44. VASCULAR
Abdominal aortic aneurysms can be measured
and followed up with conventional
ultrasonography.
• More recently, it has been used to follow up
arterial limb grafts to predict and prevent graft
stenosis. Ultrasonography is an effective
method of detecting clots and reduced flow in
larger vessels of
patients with deep
vein thrombosis.

45. NEEDLE BIOPSY
Ultrasonography can be used to guide needle
aspiration and biopsy of masses of deep
organs as liver & small parts such as the
thyroid and parathyroid glands, salivary
glands, breasts, testes, and eyes.
In last decade tiny probes has been developed
which can be attached to endoluminal
devices to provide high resolution images.
ENDO-CAVITARY EXAMINATION
As transvaginal ultrasonography of the uterus
and Ovaries, transrectal examination of the
prostate, and transoesophageal examination
of the heart and aorta.

46. PAEDIATRICS
-Excellent images of the brain of neonates can be
obtained by placing the ultrasound probe on the open
fontanelle. This allows identification of haemorrhage
in the ventricles or brain substance. Congential
anomalies, including the presence and causes of
hydrocephalus.
-Intussusception & pyloric stenosis can be identified,
avoiding the need for contrast media and ionising
radiation.
-Ultrasonography is now used in screening infants to
exclude congenital hip dislocation at an early and
treatable stage, identify effusion into the joint and
allow aspiration of fluid to exclude septic arthritis.

47. SMALL PARTS
Scrotum - It is the best investigation for
scrotal masses.
Epididymitis can be identified on it.
Testicular torsion is diagnosed clinically,
but ultrasonography may help to show
an abnormal lie of the testis & Doppler
scanning may reveal absent perfusion.
Thyroid - It is used to guide biopsy of
thyroid masses. It differentiates between
a multinodular goitre and a
homogeneously enlarged gland and may
confirm retro-sternal extension.

48. Breast - It is not sensitive enough to be used to
screen cancer at any age.
It is useful in patients with a palpable mass which
cannot be seen on mammography, in
differentiating a fibroadenoma from a cyst & in
investigating painful lumps such as abscesses,
which cannot be compressed for mammography.
Eye - It is quick, painless, and simple. The probe is
placed directly on the closed eyelid, which is
first covered in ultrasound jelly.
It can show retinal detachments and vitreous
haemorrhage and detect foreign bodies such as
metal splinters in the eye or the retro-orbital
tissues

49. When should we do
U/S examination &
what is its priority
between other
imaging modalities
in various cases?

50. Various imaging modalities may be used to
investigate a single patient or a single disease
process. Knowledge as to the natural history or
expected course of illness is necessary to
employ the appropriate imaging tool.
EXAMPLES:
65 year old man with chest pain
Diagnosis: Acute Myocardial Infarction
PLAIN FILM - CXR: to assess heart and lungs;
CHF
ECHOCARDIOGRAPHY (US): chamber size,
vessels to heart, estimate ejection fraction
CORONARY ANGIOGRAPHY: to assess blood
vessels - anything surgically correctable

51. 30 year old man with scrotal mass
Diagnosis: Testicular Cancer
Ultrasound: To assess testis and mass
CT: To look for retroperitoneal adenopathy
(that's where the disease spreads)
CXR: To assess for metastatic disease to chest.
Female patient with pelvic mass
Diagnosis: Uterine fibroids Vs adnexal mass.
Ultrasound:To assess uterus, adnexa, ovaries,
identify mass & follow it.
MRI: To look for invasion of surrounding
structures & grading of mass.

52. Patient with neck swelling
Diagnosis: Superficial mass (thyroid, salivary,
L.N.)
Ultrasound: Show size of gland, nodules or
lymphadenopathy.
CT or MRI: for retrosternal extension & laryngeal
or tracheal involvement, deep lesions.
Patient in shock after car accident
Diagnosis: Fracture ribs, pneumothorax,
subdural Hge, internal Hge after rupture
kidney.
Plain CXR: for ribs & pneumothorax.
CT Brain: for brain Hge.
Abd. Ultrasound:for internal Hge, visceral injury.

53. Computerized Ultrasound Tomography
In ultrasound tomography the aim is to
reconstruct an image, a cross section of
the object from projected data obtained
when ultrasound passes trough the
object.
The methods are based on the amplitude of
the signal or the time that it takes for the
sound to pass trough object.

54. WHAT IS THE FUTURE OF ULTRASOUND?
New ultrasound equipment offers improved
image quality and faster diagnosis & portable
equipments for paramedics and the military.
Future technology may allow the waves to travel
in multiple directions so that the equipment can
interpret the resulting images differently.
Virtual ultra-sonography will take a major role in
diagnosis in near future.
High-intensity focused ultrasound (or “HIFUS”)
allows medical professionals to diagnose and
immediately treat cancerous tumors.

55. That could change also,
researchers have
developed a line of
low cost ultrasound
USP-based probes
that run on laptops
and small PCs and are
now working on a new
generation of
cellphone-based
probes.