2. Ultrasound waves
• Sound waves are mechanical vibrations that
can be described in terms of frequency or
Hertz (Hz), ie, the number of repetitions or
cycles per second.
• Other characteristics include wavelength, the
distance between excitations, measured in
mm; and the amplitude of excitation,
measured in decibels (dB).
3.
4. • Medical ultrasound imaging typically uses
sound waves at frequencies of 1,000,000 to
20,000,000 Hz (1.0 to 20 MHz).
• In contrast, the human auditory spectrum
comprises frequencies between 20 and 20,000
Hz.
5. INTERACTION OF ULTRASOUND
WAVES WITH TISSUES
• When ultrasound beam hits the target it can
undergo
• Reflection
• Refraction
• Scattering
• Attenuation – Reduce signal strength
6. ULTRASOUND TRANSDUCERS
• Ultrasound transducers use piezoelectric crystals to
both generate and receive ultrasound waves
• These crystals (quartz or titanate ceramic) alternately
compress and expand the alternating electric current
that is applied, thereby generating the ultrasound
wave.
• Following a brief period of transmission, typically 1 to
6 microseconds, the same crystal also acts as a
receiver.
• When a reflected ultrasound wave impacts the
piezoelectric crystal, an electric current is generated.
10. • 2D image is generated from data obtained
electronically using a phased-array transducer.
• Since each scan line of data requires a finite
period of time for transmission and reception,
the time required to complete each 2D image
is directly related to the number of scan lines.
11. Tomographic View
• Each tomographic view is defined by the
transducer position
• parasternal
• apical
• subcostal
• suprasternal
12. Views
• Views obtained by manipulation of transducer
by combined angulation and rotation
• long axis
• short axis
• four-chamber
• five-chamber.
13.
14. Parasternal long axis view
• Third or fourth left intercostal space,
immediately adjacent to the sternum
15.
16. Right ventricular inflow and outflow-
PLAX
• Infero medial
angulation of
Parasternal long axis
view
• Visualize IVC, RA ,RV, TV
17.
18. Parasternal short axis
• From the parasternal long axis orientation, a 70º
to 110º clockwise rotation of the transducer
• superior and inferior transducer manipulations
permits delineation of the parasternal short axis
views
• base (aortic valve)
• basal left ventricular (mitral valve)
• mid-left ventricular (papillary muscle)
• and apical left ventricular levels
24. MERCEDES BENZ SIGN
All three leaflets of the
aortic valve may be
identified, forming a "Y"
configuration during
ventricular diastole, with
the interatrial septum
adjacent to the
noncoronary cusp.
27. ANALYSIS OF WALL MOTION PSAX
• Slight inferior
angulation of PSAX view
helps in assessing wall
motion abnormalities in
Myocardial infarction
patients
28. Apical 4 chamber view
• Transducer at
apex
• Visualize all 4
chambers
29.
30.
31. Apical five-chamber
• Anterior angulation and
slight clockwise rotation
of the transducer .
• permits imaging of the
left ventricular outflow
tract, right and left
leaflets of the aortic
valve, and proximal
ascending aorta
33. Apical Long Axis view
• Further
counter
clockwise
direction and
anterior
angulation
34. Subcostal view
• obtained with the patient
supine in full inspiration
to bring the heart closer
to the imaging probe and
with the knees bent to
relax the abdominal
musculature
• The transducer is
positioned immediately
below or to the right of
the xiphoid process.
38. Suprasternal notch
• with the patient supine
and the neck extended,
the transducer is placed
in the suprasternal
notch to obtain an
image of the distal
ascending, transverse,
and proximal
descending aorta
