The document discusses diffusion magnetic resonance imaging (DW-MRI). It begins by explaining Fick's law of diffusion and how Einstein later derived the diffusion coefficient. It then discusses how DW-MRI can be used to measure diffusion in tissues by acquiring images with diffusion sensitizing gradients at different b-values. Higher b-values lead to more signal loss and allow generation of apparent diffusion coefficient maps, which provide quantitative maps of tissue diffusivity. Clinical applications of DW-MRI include tissue characterization, tumor staging, and assessing and monitoring treatment response.
Its important to recognise the myelination pattern in neonates and infants. This presentation talks about the myelination pattern and imaging of white matter diseases in children.
Magnetic Resonance Angiography and VenographyAnjan Dangal
Introduction to MR Angiography and Venography Procedure of Brain . Includes Indication, MRI protocol, planning and anatomy as well as brief intoduction to physics behind MRA and MRV principle.
Its important to recognise the myelination pattern in neonates and infants. This presentation talks about the myelination pattern and imaging of white matter diseases in children.
Magnetic Resonance Angiography and VenographyAnjan Dangal
Introduction to MR Angiography and Venography Procedure of Brain . Includes Indication, MRI protocol, planning and anatomy as well as brief intoduction to physics behind MRA and MRV principle.
Diffusion tensor imaging (DTI) is an MRI technique that measures water molecule diffusion and its directionality. The most commonly used outcome measures are fractional anisotropy (FA) and (rotationally indifferent) mean diffusivity (MD). Tractography is an additional DTI-based technique for the mapping of discrete fiber tracks, using defined originating regions (‘seeds’) and statistical procedures that can follow the trajectories of white-matter tracks from this region. Because water diffusion in the brain is mainly restricted by fiber tracts, DTI has been suggested as an indirect marker for white-matter integrity. In several types of brain lesions, including tumors, multiple sclerosis plaques, or ischemic lesions, DTI has been found to complement other clinical data in the characterization of these lesions.
In epilepsy, DTI might help identify and characterize epileptogenic lesions such as hippocampal sclerosis or FCD. In proven hippocampal sclerosis, the epileptogenic hippocampus demonstrates increased MD and decreased FA. Prospective studies are needed to investigate the potential of DTI to detect the epileptogenic side in medial temporal lobe epilepsy without clear MRI abnormalities. Besides changes in the mesial temporal lobe structures themselves, other white-matter abnormalities (e.g., in the corpus callosum and internal capsule) have been found to be associated with hippocampal sclerosis. At present, no clear relation between the extension of extrahippocampal abnormalities and success of surgery has been found, but comprehensive studies on this interesting topic are missing.
In FCD and other types of cortical malformations, DTI and tractography have been used to characterize changes in subcortical connectivity. In many cases, diffusion changes are found not only close to the cortical lesion but also in adjacent subcortical regions that appear unremarkable in conventional MRI. This finding again raises the question of whether the extent of subcortical involvement can be used to predict surgery outcome and improve surgical planning. DTI might also prove useful in the detection of lesions undetected by conventional MRI. A recent study by Rugg-Gunn and colleagues found a significant increase in diffusivity in 8 of 30 patients with cryptogenic focal epilepsy; in 6 of these patients, the locus of the increase overlapped with the localization of EEG abnormalities, suggesting that DTI might be an additional tool for the detection of MRI-negative epileptogenic foci.
Besides the potential of DTI in characterizing epileptogenic regions, it is a promising tool for investigating the association between structural connectivity and functional changes associated with epilepsy and epilepsy surgery. Powell and colleagues found, e.g., a reduced left and enhanced right-hemispheric interconnectivity in patients with left temporal lobe epilepsy (TLE) than in healthy controls and patients with right TLE. These structural changes might be related to language
Title: Sense of Taste
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 structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
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Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
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
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
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!
MANAGEMENT OF ATRIOVENTRICULAR CONDUCTION BLOCK.pdfJim Jacob Roy
Cardiac conduction defects can occur due to various causes.
Atrioventricular conduction blocks ( AV blocks ) are classified into 3 types.
This document describes the acute management of AV block.
Explore natural remedies for syphilis treatment in Singapore. Discover alternative therapies, herbal remedies, and lifestyle changes that may complement conventional treatments. Learn about holistic approaches to managing syphilis symptoms and supporting overall health.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
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2 Case Reports of Gastric Ultrasound
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
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.
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
2. What is diffusion?
• Fick’s Law (1855, Adolf Fick)
J : diffusion flux (mol/m2s)
D : diffusion coefficient or diffusivity (m2/s)
Φ : Concentration in dimensions (mol/m3)
x : the position (m)
t : time (s)
2
3. What is diffusion?
• Brownian motion (Robert Brown, 1827)
– the presumably random drifting of particles suspended in a fluid
The characteristic bell-shaped curves of
the diffusion of Brownian particles.
3
4. What is diffusion?
• Einstein recognized that Brownian motion was associated with diffusion
– No macroscopic concentration gradient is needed.
– Self-diffusion arising from local concentration fluctuations
• Einstein derived the self-diffusion coefficient of the Brownian particle
– Einstein expressed the energy change as the total work done by the particles contained within
the volume
– Diffusion coefficient
• Einstein rewrote Fick’s laws for the diffusion
– in terms of diffusion under probability gradients
𝐷 =
𝑘 𝐵 𝑇
6𝜋𝜂𝑅
: Sutherland-Einstein relation (1905)
𝑘 𝐵 ∶ 𝐵𝑜𝑙𝑡𝑧𝑚𝑎𝑛𝑛′
𝑠 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
𝜂 ∶ viscosity
T ∶ absolute temperature
R ∶ radius of the spherical particle
𝐾𝑛
𝜁
− 𝐷
𝛿𝑛
𝛿𝑥
= 0
𝐾 ∶ 𝑛𝑒𝑡 𝑓𝑜𝑟𝑐𝑒
𝑛 ∶ the number of Brownian particles per unit volume
𝜁 ∶ friction
D ∶ diffusion coefficient
X ∶ position
𝑃 𝑟 𝑟′
, 𝑡 : 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛𝑎𝑙 𝑝𝑟𝑜𝑏𝑎𝑏𝑙𝑖𝑡𝑦 𝑡ℎ𝑎𝑡 𝑎 𝑝𝑎𝑟𝑡𝑖𝑐𝑙𝑒 𝑠𝑡𝑎𝑟𝑡𝑖𝑛𝑔 𝑎𝑡 𝑟 𝑎𝑡 𝑡𝑖𝑚𝑒 𝑧𝑒𝑟𝑜 𝑤𝑖𝑙𝑙 𝑚𝑜𝑣𝑒 𝑡𝑜 𝑟′
𝑎𝑓𝑡𝑒𝑟 𝑎 𝑡𝑖𝑚𝑒 𝑡
: Einstein equation for diffusion
4
6. How to measure the diffusion in MRI
• A review of MR imaging sequences
Gradient Echo
sequence
Spin Echo
sequence
6
7. How to measure the diffusion in MRI
7
Allen W. Song, Brain Imaging and Analysis Center, Duke University,
“Principles of MRI Physics and Engineering”
Gradient Echo DW-MRI Spin Echo DW-MRI
• Almost any MR imaging sequence can be designed to be sensitive to diffusion
– By adding magnetic field gradients
• To magnetically label spins carried by diffusing molecules
• Only parallel component has an effect
8. How to measure the diffusion in MRI
Stationary
water
Mobile
water
Stationary
water
Mobile
water
8
9. How to measure the diffusion in MRI
• The first gradient pulse
– Alters the phase shift of each proton
– By an amount dependent on the water molecule’s spatial location relative to the gradient
• The second gradient pulse
– if the water molecule does not move between the application of the first and second
gradient pulses
• Reverse this phase shift
– If there is movement of the water molecule between application of the first and second
gradient pulses
• Complete rephasing cannot happen, causing signal loss from this spatial location
• The amount of signal loss is directly proportional to the degree of water motion (the protons’
mean diffusional path length)
• Two components measured
– Magnitude: the extent to which protons are free to diffuse
• Signal loss ∝ degree of water motion (the protons’ mean diffusional path length)
– Direction: preferential diffusion direction
• Signal loss is proportional to the motion component in the same direction as the diffusion
gradient. No signal loss would occur if the motion was perpendicular to the gradient direction.
9
10. How to measure the diffusion in MRI
Gradient and spin
90
RF
Dephasing
Rephasing
10
12. Equation of diffusion attenuation, and b-value
• There is a particular problem
– The combination of the imaging and the diffusion gradient pulses produce attenuation
effects
• So, b-value is suggested
– To summarize all gradient effects (diffusion and imaging pulses)
– The diffusion sensitivity of the sequence
– Without additional gradients, SE imaging sequences has very low b-values (around 1 s/mm2)
𝐴 𝑇𝐸 : ln
𝑆
𝑆𝑜
= −𝛾2 𝐺2 𝛿2 ∆ −
𝛿
3
𝑫 = −𝑏𝑫
b-value
SignalIntensity
D
12
13. Various sequences of diffusion-weighted MRI
• Pulsed field gradient spin echo (PFGSE)
• Double pulsed gradient spin echo
– Two gradient pulse pairs on the same spin magnetization
– To compensate flow
• Stimulated echo
• Gradient echo
𝐴 𝑇𝐸 = exp(−𝛾2 𝐺2 𝛿2 ∆ −
𝛿
3
𝐷)
𝐴 𝑇𝐸 = exp(−𝛾2 𝐺2 𝛿2 ∆ −
𝛿
3
+
𝜀3
30
−
𝛿𝜀3
6
𝐷)
13
14. We can get diffusion-weighted MR images
• Among various MRI images
– T1-weighted MRI
– T2-weighted MRI
– FLAIR (Fluid attenuated inversion recovery)
– Proton Density weighted MRI
– Diffusion-weighted MRI
– Diffusion Tensor Imaging
– Susceptibility Weighted Imaging (SWI)
– Dynamic Susceptibility Contrast (DSC) MRI
– Magnetic Resonance Spectroscopy (MRS)
– Functional MRI
CT T1
weighted
T2-
weighted
Diffusion
weighted
ADC map
14
15. Diffusion-weighted image vs. Diffusion map
• Diffusion-weighted image
– Darkness: high diffusion
– Brightness: low diffusion
– Intensity is affected by many other parameters than diffusion
• Diffusion map (ADC map)
– To obtain pure maps of the diffusion coefficient
– By acquiring two images with different b-values, b and b0
– Darkness: low, slow diffusion
– Brightness: high, fast diffusion
𝐴 = [1 − exp −
TR
𝑇1
]exp −
𝑇𝐸
𝑇2
exp(−𝑏𝑫)
𝑫 𝑥,𝑦,𝑧 = −ln[
𝐴 𝑥,𝑦,𝑧 𝑏
𝐴 𝑥,𝑦,𝑧 𝑏0
]/(𝑏 − 𝑏0)
Diffusion-weighted image ADC map
15
16. Diffusion map
• Two b-value acquisitions
– Best precision: b-b0 = 1/D (in the brain b-b0 = 1000 to 1500 s/mm2)
• More than two b-value acquisitions
– Better accuracy
– To get further information on tissue microstructure and dynamics
16b-value
SignalIntensity
D
17. IVIM
• IVIM (intravoxel incoherent motion)
– Pseudo-diffusion process from movement of the blood in the microvasculature
– A means to cover all molecular displacements to which “diffusion” MRI could be sensitive
– Diffusion measurements with MRI may include perfusion effects and not just true diffusion
• Perfusion effects at very low b-values (<200 s/mm2)
– Only two b-values (0 and 1000 s/mm2) could include perfusion effect
• Overestimation of the true diffusion coefficient D
17
18. ADC (apparent diffusion coefficient)
• ADC map
– Describes microscopic water diffusibility in the presence of factors that restrict diffusion
within tissues.
– ADC is measured by combining two diffusion-weighted images
• typically with (Sb) and without (So) diffusion weighting
• or using two b-values
– Multiple b-values are needed
• To differentiate between perfusion and diffusion
– The area of high diffusion is represented as a bright area; a high ADC value
18
19. ADC (apparent diffusion coefficient)
• To take into account diffusion and pseudo-diffusion processes
• By replacing the microscopic diffusion coefficient D with a global parameter, ADC
• In the brain, as larger b-values can generally be used and f is very small (2~4%)
ADC ≡ −ln[
𝐴(𝑏)
𝐴(𝑏0)
]/(𝑏 − 𝑏0)
𝐴𝐷𝐶 ≈ 𝐷 + 𝑓/𝑏 f : perfusion fraction
Diffusion-weighted image ADC map
19
20. Fast and slow diffusion pool
• The biexponential model
𝐴 = 𝑓𝑠𝑙𝑜𝑤 exp −𝑏𝐷𝑠𝑙𝑜𝑤 + 𝑓𝑓𝑎𝑠𝑡exp(−𝑏𝐷𝑓𝑎𝑠𝑡)
f: the volume fraction (fslow + ffast = 1)
D: the diffusion coefficient
20
21. Clinical applications of DW-MRI
• Clinical applications
– Tissue characterization (differentiating benign from malignant lesions)
– Tumor staging
– Predicting treatment outcomes (before and soon after starting therapy)
– Monitoring treatment response after chemotherapy or radiation
– Differentiating post-therapeutic changes from residual active tumor
– Detecting recurrent cancer
– Detecting lymph node involvement by cancer
21
23. Primary brain tumor in DW-MRI
23
Charles-Edwards, E.M. and deSouza, N.M. (2006). “Diffusion-weighted magnetic
resonance imaging and its application to cancer.” Cancer imaging : the official
publication of the International Cancer Imaging Society, 6, pp. 135-43.
B-value = 0 B-value = 500 B-value = 1000 ADC map
Edema
Tumor
25. Summary
• Fick’s law of diffusion → Einstein equation
• Why diffusion?
– Tissue cellularity : DW-MRI
– Connectivity : DTI
• How to measure diffusion in MRI
– By adding a pair of magnetic field gradients (diffusion gradient)
– Diffusivity → signal attenuation
• High signal : low diffusion
• Low signal : high diffusion
• The b-value
– the diffusion sensitivity of the sequence (correlated with G, ∆, 𝛿)
• ADC map: tissue cellularity
– From (more than) two DW-MRI with different b-value → ADC map
– High intensity : high diffusion
– Low intensity : low diffusion
• IVIM
– Blood flow effect analysis
• Biexponential model
– Slow and fast diffusion pool
– Intra-cellular and extra-cellular compartment
• Clinical application
– Tissue characterization
– Tumor staging
– prediction and monitoring of treatment response
25
𝐴 = 𝑓𝑠𝑙𝑜𝑤 exp −𝑏𝐷𝑠𝑙𝑜𝑤 + 𝑓𝑓 𝑎𝑠𝑡exp(−𝑏𝐷𝑓𝑎𝑠𝑡)