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Basics of sonography and anatomy of chest wall
1.
2. Basics of Chest Sonography
and Anatomy of Chest Wall
By
Gamal Rabie Agmy , MD , FCCP
Professor of Chest Diseases ,Assiut University
ERS National Delegate of Egypt
3.
4. • Diagnostic ultrasonography
is the only clinical imaging
technology currently in use
that does not depend on
electromagnetic radiation.
5. Ultrasound Transducer
Speaker
transmits sound pulses
Microphone
receives echoes
• Acts as both speaker & microphone
Emits very short sound pulse
Listens a very long time for returning echoes
• Can only do one at a time
8. Frequency
• # of cycles per second
• Measured in Hertz (Hz)
-Human Hearing 20 - 20,000 Hz
-Ultrasound > 20,000 Hz
-Diagnostic Ultrasound 2.5 to 10
MHz
(this is what we use!)
17. Transmitter
• a crystal makes energy into sound
waves and then receives sound waves
and converts to energy
• This is the Piezoelectric effect
• u/s machines use time elapsed with a
presumed velocity (1,540 m/s) to
calculate depth of tissue interface
• Image accuracy is therefore dependent
on accuracy of the presumed velocity.
18. Transducers
• Continuous mode
– continuous alternating current
– doppler or theraputic u/s
– 2 crystals –1 talks, 1 listens
• Pulsed mode
– Diagnostic u/s
– Crystal talks and then listens
19. Receiver
• Sound waves hit and make voltage
across the crystal-
• The receiver detects and amplifies
these voltages
• Compensates for attenuation
20. Signal Amplification
• TGC (time gain
compensation)
– Manual control
– Selective enhancement
or suppression of sectors
of the image
– enhance deep and
suppress superficial
*blinders
• Gain
– Manual control
– Affects all parts of the
image equally
– Seen as a change in
“brightness” of the
images on the entire
screen
*glasses
23. Displays
• B-mode
– Real time gray scale, 2D
– Flip book- 15-60 images per second
• M-mode
– Echo amplitude and position of moving
targets
– Valves, vessels, chambers
26. Image properties
• Echogenicity- amount of energy
reflected back from tissue interface
– Hyperechoic - greatest intensity - white
– Anechoic - no signal - black
– Hypoechoic – Intermediate - shades of
gray
28. Image Resolution
• Image quality is dependent on
– Axial Resolution
– Lateral Resolution
– Focal Zone
– Probe Selection
– Frequency Selection
– Recognition of Artifacts
29. Axial Resolution
• Ability to differentiate two objects along
the long axis of the ultrasound beam
• Determined by the pulse length
• Product of wavelength λ and # of cycles in
pulse
• Decreases as frequency f increases
• Higher frequencies produce better
resolution
30. Axial Resolution
• 5 MHz transducer
– Wavelength 0.308mm
– Pulse of 3 cycles
– Pulse length
approximately 1mm
– Maximum resolution
distance of two objects
= 1 mm
• 10 MHz transducer
– Wavelength 0.15mm
– Pulse of 3 cycles
– Pulse length
approximately 0.5mm
– Maximum resolution
distance of two objects
= 0.5mm
32. Lateral Resolution
• The ultrasound beam is made up of
multiple individual beams
• The individual beams are fused to
appear as one beam
• The distances between the single
beams determines the lateral resolution
33. Lateral resolution
• Ability to differentiate objects along an
axis perpendicular to the ultrasound
beam
• Dependent on the width of the
ultrasound beam, which can be
controlled by focusing the beam
• Dependent on the distance between the
objects
39. Acoustic Enhancement
• Opposite of acoustic shadowing
• Better ultrasound transmission allows
enhancement of the ultrasound signal
distal to that region
41. Acoustic Shadowing
• Occurs distal to any highly reflective or
highly attenuating surface
• Important diagnostic clue seen in a
large number of medical conditions
– Biliary stones
– Renal stones
– Tissue calcifications
42. Acoustic Shadowing
• Shadow may be more prominent than
the object causing it
• Failure to visualize the source of a
shadow is usually caused by the object
being outside the plane of the
ultrasound beam
47. Beam-Width Artifact
• Gas bubbles in the duodenum can
simulate a gall stone
• Does not assume a dependent posture
• Do not conform precisely to the walls of
the gallbladder
49. Side Lobe Artifact
• More than one ultrasound beam is
generated at the transducer head
• The beams other than the central axis
beam are referred to as side lobes
• Side lobes are of low intensity
50. Side Lobe Artifact
• Occasionally cause
artifacts
• The artifact by be
obviated by
alternating the angle
of the transducer
head
53. Reverberation Artifacts
• On the monitor parallel bands of
reverberation echoes are seen
• This causes a “comet-tail” pattern
• Common reflective layers
– Abdominal wall
– Foreign bodies
– Gas
59. Traditionally, air has been considered the
enemy of ultrasound and the lung has been
considered an organ not amenable to
ultrasonographic examination. Visualizing the
lung is essential to treating patients who are
critically ill.
60.
61.
62.
63. Lines written on ultrasound in the five
Light’s editions
43
78
102
122
278
1983 1990 1995 2001 2008
68. A high-resolution linear transducer of 5–10 MHz is
suitable for imaging the thorax wall and the
parietal pleura (Mathis 2004). More recently
introduced probes of 10–13 MHz are excellent for
evaluating lymph nodes (Gritzmann 2005), pleura
and the surface of the lung.
For investigation of the lung a convex or sector probe
of 3–5 MHz provides adequate depth of penetration.
77. Normal lung surface
Left panel: Pleural line and A line (real-time).
The pleural line is located 0.5 cm below the rib line in the adult.
Its visible length between two ribs in the longitudinal scan is
approximately 2 cm. The upper rib, pleural line, and lower rib (vertical
arrows) outline a characteristicpattern called the bat sign.
95. Duplex Doppler sonogram of a 5 x 3 cm hypoechoic mass
(adenocarcinoma) in upper lobe of left lung shows blood flow
at margin of tumor near pleura. Spectral waveform reveals
arteriovenous shunting: low-impedance flow with high
systolic and diastolic velocities. Pulsatility index = 0.90,
resistive index = 0.51, peak systolic velocity = 0.47 m/sec, end
diastolic velocity =0.23 m/sec, peak frequency shift = 3.8 kHz,
96. Duplex Doppler sonogram in 67-year-old man with pulmonary
tuberculosis in lower lobe of left lung shows several blue and
red flow signals in massiike lesion. Spectral waveform reveals
high-impedance flow. Pulsetility index = 4.20, resistive index =
0.93, peak systolic velocity = 0.45 m/sec, end diastolic
velocity = 0.03 m/sec, Doppler angle = 21#{
