Our concepts of heart disease are based on the enormous reservoir of physiologic and anatomic knowledge derived from the past 70 years' of experience in the cardiac catheterization laboratory.
As Andre Cournand remarked in his Nobel lecture of December 11, 1956, the cardiac catheter was the key in the lock.
By turning this key, Cournand and his colleagues led us into a new era in the understanding of normal and disordered cardiac function in huma
Diagnostic catheters for coronary angiography Aswin Rm
Overview of diagnostic catheters used in coronary angiography
Guide catheters not included
History of coronary catheters
Radial techniques and catheters
Based on the principle that the distal coronary pressure measured during vasodilation is directly proportional to maximum vasodilated perfusion.
FFR is defined as the ratio of maximum blood flow in a stenotic artery to maximum blood flow in the same artery if there were no stenosis.
FFR is simply calculated as a ratio of mean pressure distal to a stenosis (Pd) to the mean pressure proximal stenosis, that is the mean pressure in the aorta (Pa), during maximal hyperaemia.
Our concepts of heart disease are based on the enormous reservoir of physiologic and anatomic knowledge derived from the past 70 years' of experience in the cardiac catheterization laboratory.
As Andre Cournand remarked in his Nobel lecture of December 11, 1956, the cardiac catheter was the key in the lock.
By turning this key, Cournand and his colleagues led us into a new era in the understanding of normal and disordered cardiac function in huma
Diagnostic catheters for coronary angiography Aswin Rm
Overview of diagnostic catheters used in coronary angiography
Guide catheters not included
History of coronary catheters
Radial techniques and catheters
Based on the principle that the distal coronary pressure measured during vasodilation is directly proportional to maximum vasodilated perfusion.
FFR is defined as the ratio of maximum blood flow in a stenotic artery to maximum blood flow in the same artery if there were no stenosis.
FFR is simply calculated as a ratio of mean pressure distal to a stenosis (Pd) to the mean pressure proximal stenosis, that is the mean pressure in the aorta (Pa), during maximal hyperaemia.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Flu Vaccine Alert in Bangalore Karnatakaaddon Scans
As flu season approaches, health officials in Bangalore, Karnataka, are urging residents to get their flu vaccinations. The seasonal flu, while common, can lead to severe health complications, particularly for vulnerable populations such as young children, the elderly, and those with underlying health conditions.
Dr. Vidisha Kumari, a leading epidemiologist in Bangalore, emphasizes the importance of getting vaccinated. "The flu vaccine is our best defense against the influenza virus. It not only protects individuals but also helps prevent the spread of the virus in our communities," he says.
This year, the flu season is expected to coincide with a potential increase in other respiratory illnesses. The Karnataka Health Department has launched an awareness campaign highlighting the significance of flu vaccinations. They have set up multiple vaccination centers across Bangalore, making it convenient for residents to receive their shots.
To encourage widespread vaccination, the government is also collaborating with local schools, workplaces, and community centers to facilitate vaccination drives. Special attention is being given to ensuring that the vaccine is accessible to all, including marginalized communities who may have limited access to healthcare.
Residents are reminded that the flu vaccine is safe and effective. Common side effects are mild and may include soreness at the injection site, mild fever, or muscle aches. These side effects are generally short-lived and far less severe than the flu itself.
Healthcare providers are also stressing the importance of continuing COVID-19 precautions. Wearing masks, practicing good hand hygiene, and maintaining social distancing are still crucial, especially in crowded places.
Protect yourself and your loved ones by getting vaccinated. Together, we can help keep Bangalore healthy and safe this flu season. For more information on vaccination centers and schedules, residents can visit the Karnataka Health Department’s official website or follow their social media pages.
Stay informed, stay safe, and get your flu shot today!
2. Sound
▪ Mechanical vibration transmitted through an elastic medium
▪ Pressure waves when propagate through air at appropriate frequency
produce sensation of hearing
Vibration Propagation
3. As sound propagates through a medium
the particles of the medium vibrate
Air at equilibrium, in the
absence of a sound wave
Compressions and rarefactions
that constitute a sound wave
4. ULTRASOUND
▪ Ultrasound is sound with a frequency over 20,000 Hz, which is the
upper limit of human hearing.
▪ The basic principles and properties are same as that of audible sound
▪ Frequencies used for diagnostic ultrasound are between 2 to 20 MHz
6. Sine wave:
▪ Amplitude - maximal
compression of particles
above the baseline
▪ Wavelength - distance
between the two nearest
points of equal pressure
and density
One Compression and rarefaction constitute one sound wave . It can be
represented as “Sine wave”.
wavelength = speed/frequency
7. Amplitude
• Defines the Brightness of the image
Irrespective of the Freq the Amp remains
constant
The Higher the Amp the brighter the image
and the lower the more darker the images
Returning Waves
8. FREQUENCY:
▪ Number of cycles per second
▪ Units are Hertz
▪ Ultrasound imaging frequency range 2-20Mhz
11. Velocity:
▪ Speed at which a sound wave travels through a medium(cm/sec)
▪ Average speed of ultrasound in body is 1540 m/sec
Phase
Frequency
Amplitude
Wavelength
velocity = frequency x wavelength
• Dependent on physical properties of the medium through which it travels
• Directly proportional to stiffness of the material
• Inversely proportional to density within a physiological limit
12. Rule Of Thumb:
▪ Stiffness and Speed ---- Same Direction
▪ Density and Speed ---- Opposite Direction
▪ Stiffness is related to change in shape – squishability
▪ Density is related to Weight
13. Sound velocity in different materials
Material Velocity ( m/s)
Air 330
Water 1497
Metal 3000 - 6000
Fat 1440
Blood 1570
Soft tissue 1540
14. Pulsed Ultrasound
▪ In diagnostic imaging short pulses of acoustic energy are used to
create anatomic images.
▪ Continuous wave sound can not create images. CW is used for
Doppler
▪ Two component of Pulsed Ultrasound:
– The cycles (Transmit time)
– Dead time (Receive time)
16. Pulse Duration
▪ The time from the start of pulse to end of pulse
▪ Transmit time
▪ Can not be changed by sonographer
▪ In clinical imaging its 2-4 cycles
17. Spatial Pulse Length
▪ The distance from start to the end of one pulse.
▪ Can not be changed by sonographer
▪ Determines Axial Resolution
Spatial pulse length
Time
Distance
18. Pulse Repetition Period
▪ Time from the start of one pulse to the start of next pulse
▪ Includes one pulse and one Listening time
▪ Sonographer can change PRP (listening time only and not pulse duration of period)
Time
Distance Spatial pulse length
20. Pulse Repetition Frequency (PRF)
▪ Number of Pulses created by system in one second.
▪ Not related to Frequency
▪ Determined by depth
– Shallow image -- High PRF
– Deep Image – Low PRF
22. Frequency vs. Resolution
▪ The frequency also affects the QUALITY of the ultrasound image
–The HIGHER the frequency, the BETTER the resolution
–The LOWER the frequency, the LESS the resolution
23. Frequency, Penetration & Resolution
Higher the frequency Lower the penetration and Higher the
resolution
Low the frequency higher the penetration and lower the
resolution
24. The Trade Off
▪ The trade-off between tissue resolution and penetration
▪ A 12 MHz transducer has very good resolution, but cannot penetrate
very deep into the body
▪ A 3 MHz transducer can penetrate deep into the body, but the
resolution is not as good as the 12 MHz
32. Reflection
– Occurs at a boundary between 2 adjacent tissues or media
– The amount of reflection depends on differences in
acoustic impedance (z) between media
– The ultrasound image is formed from reflected echoes
Transducer
Z = Density xVelocity
33. Angle of Incidence
Reflection from a tissue interface at
right angle. There is
stronger reflection resulting in brighter
echo.
Reflection at an angle equal to
the angle of incidence
producing less bright echo.
35. ▪ Not all the sound wave is reflected, some continues
deeper into the body
▪ These waves will reflect from deeper tissue
structures
Transducer
Transmission
36. ▪ The deeper the wave travels in the body, the
weaker it becomes
▪ The amplitude of the wave decreases with
increasing depth
Attenuation
Higher frequency ,
more attenuation
Longer the distance
(Depth), more the
attenuation
37. Scattering
▪ Redirection of sound in several directions
▪ Caused by interaction with small reflector or rough surface
▪ Only portion of sound wave returns to transducer
38. ▪ The resistance that a material offers to the passage of sound wave
▪ Velocity of propagation “v” varies between different tissues
▪ Tissues also have differing densities “ρ”
▪ Acoustic impedance
“Z = ρv”
▪ Soft tissue / bone and soft tissue / air interfaces have large “Acoustic
Impedance mismatch”
▪ Difference between Air and Blood
Acoustic Impedance
39. How Does An Ultrasound Machine Make An Image ?
– Ultrasound transducer produces “pulses” of
ultrasound waves
– These waves travel within the body and interact
with various tissues
– The reflected waves return to the transducer and are
processed by the ultrasound machine
– An image which represents these reflections is
formed on the monitor
Pulse-Echo Method
40. Imaging By Ultrasound
▪ Ultrasound imaging is performed by emitting a pulse, which is partly
reflected from a boundary between two tissue structures, and partially
transmitted.
The amount of energy being reflected from each point is given
in the diagram as the Amplitude.
41. B- Brightness
mode shows
the energy as
the brightness
of the point
M- Motion mode the
reflector is moving so
if the depth is shown
in a time plot, the
motion will be seen
as a curve
A
B
C
42. 2-Dimensional Imaging
▪ Provides more structural and functional
information
▪ Rapid repetitive scanning along many different
radii with in an area in the shape of a fan
▪ 2-D image is built up by firing a beam , waiting
for the return echoes, maintaining the
information and then firing a new line from a
neighboring transducer along a neighboring line
43.
44. A single ‘FRAME’ being formed
from one full sweep of beams
A ‘CINE LOOP’ from multiple FRAMES
45. Position of Reflected Echoes
▪ How does the system know the depth of the
reflection?
▪ TIMING
– The system calculates how long it takes for the echo to return
to the transducer
– The velocity in tissue is assumed constant at 1540m/sec
Velocity = Distance xTime
2
46. How Is An Image Formed On The Monitor?
▪ The amplitude of each reflected wave is represented by a
dot
▪ The position of the dot represents the depth from which
the echo is received
▪ The brightness of the dot represents the strength of the
returning echo
▪ These dots are combined to form a complete image
51. ▪ Spatial Resolution
– also called Detail Resolution
– the combination ofAXIAL and LATERAL resolution
– some customers may use this term
Types of Resolution
52. Axial Resolution
– specifies how close together two objects can be
along the axis of the beam, yet still be
detected as two separate objects
– frequency (wavelength) affects axial resolution
▫ Determinants:
▫ Wavelength – smaller the
better
▫ Pulse length – shorter the
train of cycles greater the
resolution
53. Lateral Resolution
– the ability to resolve two adjacent objects that are
perpendicular to the beam axis as separate objects
– Beamwidth affects lateral resolution
▫ Determinants:
▫ Beam width – smaller
the better
▫ Depth
▫ Gain
56. ▪ The lateral resolution is approximately equals
the beam diameter.
▪ Since the beam diameter varies with depth,
the lateral resolution also varies with depth.
▪ It is best at near zone ( focal ) length.
57. ▪ The ability to accurately locate the position of moving
structures at particular instants in time
▪ The temporal resolution is limited by the sweep speed of
the beam.
▪ And the sweep speed is limited by the speed of sound, as
the echo from the deepest part of the image has to return
before the next pulse is sent out ad a different angle in the
neighboring beam
Temporal resolution:
58. As the depth of the sector determines
the time before next pulse can be sent
out, higher depth results in longer time
for building each line, and thus longer
time for building the sector from a
given number of lines, i.e. lower frame
rate.
Thus reducing the desired depth of the
sector results in shorter time between
pulses, and thus shorter time for
building each line, shorter time for
building the same number of lines, i.e.
higher frame rate.
59. • Use Depth and NOT Zoom
• Adjust sector size
• Adjust gain
• Decreasing the line density
Improving Temporal Resolution (Frame Rate)
60. • Use Depth and NOT Zoom
In the image to the left, the depth has been halved, reducing the time for
building each line to half, thus also halving the time for building the full
sector, doubling the frame rate
(Temporal Resolution)
61. Reducing the line density instead and maintaining sector
width, results in lower number of lines, i.e. lateral resolution,
and gives the same increase in frame rate.
Reducing sector width, but maintaining the line density, gives
unchanged lateral resolution but higher frame rate, at the cost
of field of view.
• Line density & Sector width
(Temporal Resolution)
62. ▪ Contrast Resolution
– the ability to resolve two adjacent objects of similar
intensity/reflective properties as separate objects
Types of Resolution
65. DEPTH:
The deeper the field of the image, the slower the frame rate
The smallest depth that permits display of the region of interest should be employed
67. Signal-To-Noise Ratio
▪ Returning ultrasound waves are referred to as signal,
while background artifact is referred to as noise.
▪ Increasing the gain increases the signal-to-noise ratio.
68. Time Gain Compensation
• TGC will change the gain factor so that equally reflective
structures will be displayed with the same brightness
regardless of their depth.
• TGC allows amplification of ultrasound beams from deeper
depths because different amplitudes of ultrasound signals
are produced when received from different depths.
• MoreTGC is required for higher frequency transducers,
which create more attenuation.
70. Focusing The Beam
• Near Field
• Far Field
• Imaging quality is best within the near field.
• The length of the near field is greater at higher transducer frequencies
and wider transducer diameters.
71. FOCUS:
Indicates the region of the image in which the ultrasound beam is narrowest
Resolution is greatest in this region
72. Focusing The Beam
▪ Focusing the ultrasound beam does not affect the length of the
near field
▪ It produces a narrower beam (and higher resolution) within the
near field
▪ But makes the beam wider in the far field
▪ A phased-array transducer also offers electronic focusing, which
allows the sonographer to control the depth at which the
ultrasound beam is most tightly focused.
73. Harmonic Imaging
• When an ultrasound wave passes through the body, the
tissue generates "harmonic ultrasound waves" because
the tissue resonates.
• The resonance frequency is typically a multiple of the
original frequency (transmitted frequency)
• Fundamental components are filtered out.
• Images produced with harmonic imaging have a higher
resolution and are associated with fewer artifacts than
conventional (fundamental) imaging
76. ▪ Thus frame rate is a compromise
between sector size (width and depth),
resolution (line density).
77. ▪ High frequency transducers produce pulses with
shorter wave length and higher longitudinal resolution.
78. Lateral resolution.
▪ The minimum distance that 2 side by side structures can be
separated and still produce 2 distinct echoes.
•• •
•
Only one here
2 structures seen here
79.
80. More foci per image.
▪ More sound pulses per line.
▪ Superb lateral resolution at all depths.
▪ More time per image scan line.
▪ More time to create a frame.
Lower frame rate.
81. Multiple focal zones.
▪ An ultrasound pulse has only a single focal zone.
▪ By using multiple sound beams with different focal
depth to create a single image line the lateral
resolution is optimal at all depths
85. Ultrasound Interactions with Tissue Interfaces
Arrow representVectors whose length equal the strength & direction
of the reflected signal
A and B represent specular (mirror like) reflectors,
the B return signal does not return to the transducer
C and D have a rough surface that is typical of human tissue
E are objects smaller than a wavelength & therefore scatter the
energy
86. Interactions of Ultrasound Waves with
Tissue
The interactions will determine the types of images &
artifacts that are generated
92. Reflection:
▪ Occurs when some of the propagating acoustic energy
is redirected and returns toward the transducer.
▪ Reflection off of a very smooth reflector such as a
mirror are called specular
Reflection and incidence.
93. ▪ if the boundary between 2 media has
irregularities, then the wave is distributed in a
number of different directions.
▪ It occurs when a sound wave strikes material
whose size is approximately equal to or smaller
than the wavelength of the cycles in the pulse.
Scattering:
99. In clinical ultrasound imaging 99% or more of
the incident energy is transmitted forward at a
boundary between soft tissues.
100. Reflection with oblique incidence.
▪ With oblique incidence, we cannot predict whether
transmission and/ or reflection will occur.
101. Refraction.
▪ Is a change in direction, or a bending away from a straight
line path, of a wave traveling from one medium to another.
▪ Refraction occurs only when there are:
1. Different Propagation Speed.
2. Oblique Incidence between the sound wave and the
boundary.
103. Range equation.
How does an imaging system
determine the depth of a reflecting
surface?
Time-Of-Flight.
104. ▪ Time-Of-Flight: the go-return time
Is the elapsed time between pulse production and echo
reception by the transducer.
▪ Estimating distance from the go-return time is called
echo ranging.
105.
106.
107.
108.
109. Machines
There are 5 basic components of an ultrasound scanner that are required for
generation, display and storage of an ultrasound image.
1. Pulse generator - applies high amplitude voltage to energize the crystals
2. Transducer - converts electrical energy to mechanical (ultrasound) energy
and vice versa
3. Receiver - detects and amplifies weak signals
4. Display - displays ultrasound signals in a variety of modes
5. Memory - stores video display
110. ▪ Depicted as sine wave-peaks and troughs
▪ One cylce=one compression + one rarefaction
▪ Distance between 2 similar points represent
wavelength
▪ 0.15 to 1.5 mm in soft tissue
▪ Frequency- number of wavelengths per unit time
▪ V=f X λ(v=velocity,f =frequency, λ is wavelength)
111. ▪ Velocity of sound=1540 m/sec in soft tissue
▪ Wavelength=1.54/f
▪ Amplitude
Measure of strength of the sound wave
Indicated by height of sine wave above and below baseline
112.
113.
114. ▪ Higher the frequency greater the resolution
▪ Higher frequency,lesser the penetration
▪ Loss of ultrasound as it propogates through a medium is
called attenuation
115. PRICIPLES OF PEIZO ELECTRIC CRYSTALS
The charges in a piezoelectric crystal are exactly
balanced, even if they're not symmetrically
arranged.
The effects of the charges exactly cancel out, leaving
no net charge on the crystal faces
the electric dipole moments—vector lines
separating opposite charges—exactly cancel one
another out.
If you squeeze the crystal , you force the charges out
of balance.
116. ▪ Now the effects of the charges (their dipole moments) no
longer cancel one another out and net positive and
negative charges appear on opposite crystal faces.
▪ By squeezing the crystal, voltage is produced across its
opposite faces- piezoelectricity
▪ The piezoelectric effect was discovered in 1880 by two French physicists, brothers Pierre and
Paul-Jacques Curie, in crystals of quartz, tourmaline, and Rochelle salt (potassium sodium
tartrate).They took the name from the Greek work piezein, which means "to press."
117. ▪ The phenomenon of generation of a voltage under mechanical stress
is referred to as the direct piezoelectric effect
▪ mechanical strain produced in the crystal under electric stress is
called the converse piezoelectric effect.
118. ▪ Ferro electrics,barium tianate,lead zirconate titanate are used
as peizo electric crystals.
▪ Dampening material-shortens the ringing response
Also absorbs backward and laterally transmitted acoustic
energy
▪ Frequency emitted by transducer is directly proportional to
propagation speed within crystal and inversely related to
thickness
119. ▪ Important feature of ultrasound is ability to direct or focus
the beam as it leaves the transducer
▪ Proximal cylindrical and distally divergent
▪ Proximal zone –Fresnel zone
▪ Divergent field is called Fraunhofer zone
▪ Imaging is optimal in near field
▪ Decreasing wavelength or increasing transducer size
increase near field
120.
121. Haemo”dynamics”
▪ Blood flow is a complex phenomenon
▪ Not a uniform liquid
▪ Flow pulsatile
▪ Vessel walls are elastic
122. Properties of Blood
▪ Density-mass of blood per unit volume
▪ Measure of resistance to accelaration
▪ Greater the density,greater the resistance to flow
▪ Viscosity:resistance to flow offered by fluid in motion
▪ 0.035 poise at 37 degree.
123.
124. Factors determining flow
▪ Flow rate is determined by
– Pressure gradient
– Resistance
▪ Viscosity of blood
▪ Radius of lumen
▪ Length of vessel
125. Types of flow
Laminar flow
Shape of parabola
Concentric layers,each parallel to vessel wall
Velocity of each layer differs
Maximal velocity is at centre of vessel
Decreasing profile towards peripheries
126.
127.
128.
129. Turbulent flow
▪ Obstruction produce increased velocities, flow vortices
▪ Whirlpools shed off in different directions producing variable
velocities- chaos
▪ Predicted by Reynolds number
▪ Reynolds number depends on
Re=( ρ x c x D)/v
ρ-Density of blood
D-Vessel diameter
c-Velocity of flow
V-viscosity
130. The Reynolds number is dimensionless
If Re is less than 1200 the flow will be -laminar
1200-2000 flow is described as -transitional
Greater than 2000 -turbulent