Basic Principles of Ultrasound Imaging
Introduction
Ultrasound imaging have different meaning to to different categories
of people based on profession or vocation
In the Heath Sector- Clinicians, Patients
In Commerce- Business & Industry
Definition :
Ultrasound Imaging (Scanning)
Commonly referred to as “Scanning,,” is the act of acquiring and interpreting
images using sound waves
Medically : Involves the use of high frequency ( higher than human hearing) sound
waves to produce images of internal organs of the body.
Technically, it is a noninvasive medical procedure that allow internal structures
of the body and hemodynamics of blood flow to be accessed or viewed as realtime images on a screen.
Ultrasound transducers send out high frequency sound waves into the body
tissues and receive reflected echoes , that are processed and displayed as
images.
For diagnostic purposes Ultrasound Doppler frequency range is 2.0 -10.5 MHz .
The frequency range for scanners for industrial or commercial use is different
Normal hearing sound wave frequency for adults is 2.5- 3.5 MHz
Basic Facts:
One major fact about Ultrasound Imaging(Scanning)
that distinguishes it from other Non Invasive Diagnostic
technology tools in the health industry is that...
“ The accuracy of the noninvasive examination is
almost exclusively dependent on the skill and the
experience of the operator.’’
Therefore, if the Operator misses the disease during
the process of scan, No matter how knowledgeable the
interpreter (Reader) is, it is unlikely that it will not be
detected unless... Other diagnostic tests were ordered
e responsibility on the operator to strive
and gain the knowledge and competency required, as
This places a uniqu
patient mistreatment / misdiagnosis due to professional incompetence and performance is
more dangerous than the disease itself..
Overview of Presentation
Part 1
Review Basic Ultrasound
Principles
Definitions and
Terminologies
Ultrasound Physics
The Transducer ( Probe )
Review Ultrasound
Modalities in
Cardiovascular Testing
Part 2

I Demonstrations

Exercises
Probe Handing ,
Orientation and Scanning
techniques
Scanning to identify body
organs
Objectives
Update awareness of various Ultrasound tests available
Enhance professional skills acquisition by Physicians to enable
proper evaluation of scanning reports or images given to
patients.
Enhance appropriate use of ultrasound systems in patient
management
Improve overall quality of patient care delivery through
accurate diagnosis
Descriptive Definitions
Terminologies
Cephalad / caudal (toward the head/toward
the tail): used
A
interchangeably with superior and inferior.
Superior / inferior (above/below): for location of a structure along the
long axis of the body.
Dorsal / ventral (backside / belly side): ventral always refers to the
belly side .
Proximal / distal (nearer the trunk or attached end.
Superficial / deep (toward or at the body surf ace / away from the body
surface or more internal).
Anterior / posterior (front / back): anterior structures are those that
are most forward—the face, chest, and abdomen.
Medial/lateral (toward the midline / away from the midline or median
plane):
Descriptive Definitions
Terminologies
Body Planes
Imaginary surface or line called a plane that lie at right angles to
one another.
Sagittal plane: divides the body into equal parts, right down the
median plane of the body, it is called a median, or mid sagittal plane.
Frontal (coronal) plane: divides the body (or an organ) into anterior
and posterior parts.
Transverse plane: divides the body into superior and inferior parts.
The terms above assume the person is in the anatomical position
•
Descriptive Definition
Terminologies
Sonography
ANECHOIC - Being echo-free or without echoes (e.g., a fluidfilled cyst).
ECHOGENICITY- Echogenic: the ability to create an
ultrasound echo .
ECHOLUCENT- same as above.
HETEROGENEOUS - mixed echoic pattern within plaqueareas of sonolucence and echogenicity.
HOMOGENEOUS - uniform plaque texture.
HYPERECHOIC - Producing echoes of higher amplitude than
normal for the surrounding medium.
HYPOECHOIC - Producing echoes of lower amplitude than
normal for the surrounding medium.
ISOECHOIC- Areas which have similar echogenicity to each
other. An isoechoic "property" makes it more difficult to see
the desired tissue structure.
SONOLUCENT- Allowing passage of ultrasonic waves without
echoes
Ultrasound Physics
Echo Doppler Principle
Mechanism of Sound Wave Generation:
Ultrasound transducers have elements made of Piezoelectric
crystals.
Major Kinds of Transducers Generated Doppler Waves
Continuous Wave (CW) Doppler and Pulse Wave(PW) Doppler
When stimulated with electricity , the crystals oscillate to produce a
high frequency sound wave signal.
Transducers send sound out and receive returning echoes from
moving reflectors in the body ( Blood and tissues ).
The wave frequency difference between the transmitted waves and
the reflected waves due to movement is called
Doppler Shift frequency
If the returning wave frequency is lower than the transmitted
frequency, the Doppler shift is considered a NEGATIVE (-)
If the returning frequency is higher, the Doppler shift is POSITIVE
(+)) Dopplers and Pulse Wave (PD)
Doppler Shift
Echo Doppler transmission is the principle mechanism use in
Ultrasound systems to detect and measure blood flow dynamics .
Doppler shift frequency is expressed as a positive or negative value,
depending on the direction of flow relative to the Doppler beam
direction
Ultrasound physics
The Doppler Equation
The Doppler Equation is used to calculate blood flow
velocity if the speed of sound in tissue is known as well as
the angle between blood flow and the ultrasound beam.
The Equation follows
Where
V=
C (±Δf )
2 foCosѲ
V= Blood flow velocity (meters/s)
C = Speed of sound in tissue; approx 1540mm/s
Δf =Doppler frequency Shift (Hz)
fo = transmitted frequency
CosѲ = Cosine function of angle between ultrasound beam and the blood
flow vector
Doppler Wave form
Parameters
Pulse Wave Doppler(PW)
have single crystal to send &receive transmission
Range Gate (TGC) (Sample Volume) at any specific
depth. - Sets Time interval in PW Mode . Amplified
contrast of reflected sound waves to form images
Pulse Repetition Interval(PRF) is number of pulse echo
cycles per second
PRF is expressed in Hertz;
11/2 PRF = Nyquist Limit
Aliasing occurs when Doppler shift frequency exceeds
11/2 of PRF.
To reduce Aliasing; increase PRF; Decrease
frequency; Decrease sample volume depth volume
Wall Filters (Hz) are set to detect or eliminate low flow
As PRF increases; Wall filters increases
The Transducer (Probe)
The Scanning Techniques
Protocols
“Standard" Protocol remain unchanged if
proven
To be effective,
Cost efficient and
accurate,
Have been no better replacements.
Protocols change as
Better methods evolve
Technological advances
New technologies mandate new test methods
Applications
Angle of Insonation
Range 45 ⁰
To
60⁰
Applications of Ultrasound Imaging in
Cardiovascular Testing
Stroke Screening
Carotid plaque estimation
Carotid Artery Duplex Examinationn
CVA stenosis evaluation
Peripheral Arterial Disease (PAD) Imaging
Segmental pressure scan stdies forr localization
Plethysmography-Skin per Fusion evaluation of blood flow with IFR photosensors
Venous Duplex Scan for Thrombosis
Duplex studies for blood clot in vessels
Trans Cranial Imaging
Meningeal arterial flow studies
Abdominal Aorta Imaging for Aneurysms
Abdominal scan for aneurysms
Renal Vascular Studies
Renal vascular flow studies
In Conclusion
Ultrasound scanning has become the most affordable diagnostic
tool in our hospitals and clinics today.
There is need for professional improvement on the overall quality
of patient care delivery through accurate diagnosis and knowledge
based evaluation of patient reports from Scanning Facilities by
physicians .
Thank You.
REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Johnston KW, Rutherford RB, Tilson MD, et al. Suggested standards for reporting on
arterial aneurysms. J Vasc Surg. 1991;13:452-458
McConathy WJ, Alaupovic P, Woolcock N, et al. Lipids and apolipoprotein profiles in
men with aneurysmal and stenosing aorto-iliac atherosclerosis. Fur J Vasc Surg.
1989;3:511-514
Emedicine- http://www.emedicinehealth.com
Meyers P, Owens C, Renal Doppler. Integrated Ultrasound Reference Guide, SDMS
Educational Foundation, Dallas TX 1996
Kohler TR, Zeirler RE, Martin RL et al. Nonivasive Diagnosis Of Renal Artery
Stenosis By Ultrasonic Duplex Scanning. J Vasc Surg 1986;4;450-6.
Taylor DC, Kettler MD, Moneta GL, et.al, Duplex Ultrasound scaniing in the diagnosis
of renal artery stenosis: A prospective evaluation. J Vasc Surg 1988;7:363-9
Hansen KJ,Tribble RW, Reavis SW, et. al., Renal duplex sonography: Evaluation of
clinical utility. J Vasc Surg 1990;12:227-36
Martin RL, Nanra RS, Bray AE, et al., Renal Hilar Doppler analysis in the Detection
of Renal Artery Stenosis. J Vasc Technol 15(4):173-180 1991
Stavros AT, Harchfield D,. Renal Doppler, renal artery stenosis, and renovascular
hypertension: direct and indirect sonographic abnormalities in patients with renal
artery stenosis.Ultrasound Quarterly, Vol.12,No.4, pp. 217-263, 1994 Raven Press
Ltd, New York
Kotval PS. Doppler Waveform parvus and tardus: a sign of proximal flow
obstruction. J Ultrasound Med 1989;8:435-40.
Rene CE, Oliva VL, Bui BT et. al., Renal Artery Stenosis: Evaluation of Doppler US
after Inhibition of Angiotensen - converting enzyme with Captopril. Radiology 1995; 196:675-679.