This document discusses different types of spin echo pulse sequences used in MRI, including conventional spin echo, fast spin echo, inversion recovery, STIR, and FLAIR. It explains the mechanisms, parameters, advantages, disadvantages and uses of each type of sequence. Conventional spin echo uses a 90° excitation pulse followed by 180° rephasing pulses to generate spin echoes. Fast spin echo reduces scan time by using multiple 180° pulses to produce an echo train. Inversion recovery and STIR suppress the signal from fat, while FLAIR suppresses cerebrospinal fluid signal. Each sequence has different contrast weighting and applications in MRI exams.
this power-point slide presentation includes lots of information like how MRI coil works. what is shimming, magnet, fringe, and design of mri coil and also magnet. this will help a lot for radiologist and technician radiographers.. thanks.
Mri spin echo pulse sequences its variations andYashawant Yadav
MRI spin echo pulse sequences its variation and applications , in this slide collection principle of spine echo pulse sequences is described with physic behind it ,, this slide also coves the inverse recovery pulse sequences and types ,,,, image weighting and parameters are explained .. hope it may be help ful.
A pulse sequence is a sequence of events, which are
needed to acquire MRI images. These events are: RF
pulses, gradient switches and signal collecting.
this power-point slide presentation includes lots of information like how MRI coil works. what is shimming, magnet, fringe, and design of mri coil and also magnet. this will help a lot for radiologist and technician radiographers.. thanks.
Mri spin echo pulse sequences its variations andYashawant Yadav
MRI spin echo pulse sequences its variation and applications , in this slide collection principle of spine echo pulse sequences is described with physic behind it ,, this slide also coves the inverse recovery pulse sequences and types ,,,, image weighting and parameters are explained .. hope it may be help ful.
A pulse sequence is a sequence of events, which are
needed to acquire MRI images. These events are: RF
pulses, gradient switches and signal collecting.
The gradient echo pulse sequence is the simplest type of MRI sequence.
The major purposes behind the gradient technique is a significant reduction in scan time. Small variable flip angle are employed , usually less than 90 degrees. which in turn allow very short repetition time thus decreasing the scan time.
Gradient echo pulse sequence differ from spin echo pulse sequence . There is no 180 degree pulse in GRE. T2 relaxation in GRE is called as T2* relaxation. Gradient can be used to either dephase or rephase the magnetic moments of nuclei.
A pulse sequence is a sequence of events, which we need to acquire MRI images.
Basic pulse sequences
1. Spin echo sequence(SE)
2. Gradient echo sequence(GRE)
3. Inversion Recovery Sequence(IR)
4. Echo Planar Imaging(EPI)
MRI spin echo sequences are a fundamental imaging technique in magnetic resonance imaging (MRI). They work by manipulating the spin of hydrogen nuclei in the body's tissues to create detailed images. In a spin echo sequence: Spin echo sequences are versatile and used in various MRI applications, including anatomical imaging, quantitative measurements, and lesion characterization. They can produce T1-weighted and T2-weighted images, depending on the specific sequence parameters chosen, offering valuable diagnostic information in medical imaging.
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
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
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
- 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
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
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.
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
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.
New Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
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. INTRODUCTION
The spin echo pulse sequence commonly uses a 90°
excitation pulse to flip the NMV into the transverse plane.
The NMV precesses in the transverse plane inducing a
voltage in the receiver coil.
The precessional paths of the magnetic moments of the
nuclei are translated into the transverse plane. When the
90° RF pulse is removed, a free inducti on decay signal
(FID) is produced. T2 * dephasing occurs almost
immediately, and the signal decays. A 180 ° RF pulse is
then used to compensate for this dephasing.
3. TYPES
Spin echo pulse sequences (spins are rephased by a 180
rephasing pulse):
1. Conventional spin echo
2. Fast or turbo spin echo
3. Inversion recovery
4. Conventional Spin Echo Mechanism:
Spin echo uses a 90° excitation pulse followed by one or
more 180° rephasing pulses to generate a spin echo.
PARAMETERS
T 1 weighting
Short TE 10– 30ms
Short TR 300– 700ms
Typical scan time 4– 6 min
Proton density/T2 weighting
Short TE 20ms/long TE 80ms +
Long TR 2000ms +
Typical scan time 7–15min
5. ADVANTAGES
The contrast is truly based on the T1 and T2 relaxation
T1 weighted images
for anatomy (high SNR)
with contrast enhancement - show pathology.
T2 weighted images also demonstrate pathology.
DISADVANTAGES
Scan times relatively
6.
7. Fast Or Turbo Spin Echo MECHANISM
The main aim is to reduce the scan time. TR, NEX, no.
of phase encoding are the function of time. Decreasing
TR,NEX affect image weighting.
Reducing phase encoding reduce spatial resolution
8. So In Fast Spin Echo Several 180° rephasing pulses to
produce train of echo called echo train
With More than one phase encoding step and more lines of
k Space filled per TR.
At each rephasing, an echo is produced and a different
phase encoding step is performed.
The no:of 180° rephasing pulse corresponds to no:of echoes
and k space lines, this number called turbo factor or echo
train length
9.
10. How The Scan Time is Reduced
Higher the turbo factor shorter the scan time as more
phase encoding steps are performed per TR
Eg. In conventional spin echo, 256 phase matrix selected
so, 256 TR elapse to complete scan
In fast spin echo, using turbo factor 16, 16 phase encoding
steps are performed every TR.
So 256÷16, scan time reduced to 1/16 of the original
Conventional one line is filled per TR FSE several lines are
filled per
11. Weighting In Fast Spin Echo
Different slope of gradient to phase shift the signal by
different amount.
Steep = less amplitude, but good spatial resolution,
effective TE is away from center
Shallow = maximum signal, effective TE is centered
12. Two Contrast Differences Occur
Fat remains bright on T2 weighted images due to multiple
RF pulses (J coupling)
Remedy: fat saturation technique
Repeated 180° pulse can increase “Magnetization transfer
effect” so muscle appear darker
Sagittal T2 weighted fast spin echo sequence through the
pelvis. Note that both fat and water have high signal
intensity.
13. Blurring may occur at edge of tissue - late echoes have low
signal amplitude.
Remedy Decrease the spacing between echoes or turbo
factor
Multiple 180˚ reduce magnetic susceptibility effect
Detrimental when looking hemorrhages
Artefact from metal implant is greatly reduced
Respiratory artefact happen when respiratory
compensation technique are not compatible. Patient holds
their breath while imaging
14. USES
Generally speaking contrast in fast spin echo is
similar to spin echo, and used in..
Musculoskeletal regions
Central nervous system
Pelvis
Parameters For T1 Weighting
TR 300 -700ms
Effective TE minimum
Turbo factor 2-8
15. For PD weighting
TR 3000-10000ms (depending on required slice number)
effective TE minimum
turbo factor 2-8 .
16.
17. For T2 weighting
TR 3000-100 00ms (depending on required slice
number)
Effective TE 80- 140ms
turbo factor 12- 30
18. Short Turbo Factor
decreased effective TE
increased T1 weighting
longer scan time
more slices per TR
reduced image blurring
Long Turbo Factor
increased effective TE
increased T2 weighting
reduced scan time
reduced slice number per TR
increased image blurring
19. Advantages
Scan times greatly reduced
High - resolution matrices and multiple NEX can
be used
Image quality improved
Increased T2 information
Disadvantages
Some flow and motion affects increased
Incompatible with some imaging options
Fat bright on T2 weighted images
Image blurring with very long echo trains
20. Single Shot Fast Spin Echo (SS-FSE)
Scan time is much reduced in SS-FSE than fast
spin echo
All lines of K space is filled in one TR
SS-FSE combines a partial Fourier technique.
Half of lines acquired in one TR and other half are
transposed
21. There is a SNR penalty,because of longer turbo factor
Specific absorption rate (SAR) is increased because of
successive 180˚ pulses.
Remedy: (to decrease SAR)
Reduce no: of slices
Reduce refocusing angle to low as 120˚.
But ..., Decreasing the SAR - will Decrease the SNR
22. Driven Equilibrium Fourier Transform
Modification of FSE ( called DRIVEN, RESTORE, or
FR-FSE)
A reverse flip angle excitation pulse applied at end of
echo train.
No need to wait for T1 Relaxation to occur
This drives any transverse magnetization into
longitudinal so available for next TR.
Water has longest T1 and T2 times, appear bright
24. Inversion recovery
Inversion recovery is a pulse sequence begins with 180
inverting pulse.
This inverts the nmv through 180 into full saturation
When the inverting pulse is removed,the nmv begins
to relax back to B.
A 90 degree excitation pulse is then applies at the time
from the 180 degree inverting pulse known as the
TI(time from inversion )
25.
26. STIR (short tau inversion recovery)
Uses TI that corresponds to the time it takes fat to
recover from full inversion to the transverse plane so
that there is no longitudinal magnetization
corresponding to fat.
A 90˚ excitation pulse is applied, so fat signal is nulled.
A TI of 100– 175ms achieves fat suppression
27. STIR should not be used in conjunction with contrast
enhancement, which shortens the T1 times of
enhancing tissues, making them bright.
28. PARAMETERS
Short TI - 150– 175ms (to suppress fat depending on
field strength)
Long TE - 50ms+ (to enhance signal from pathology)
Long TR - 4000ms+(to allow full recovery)
Long turbo factor - 16–20 (to enhance signal from
pathology)
30. FLAIR (fluid attenuated inversion
recovery)
TI corresponding to the time of recovery of CSF from
180° to the transverse plane nulls the signal from CSF.
FLAIR is used to suppress the high CSF signal in T2
weighted images so that pathology adjacent to CSF is
seen more clearly
A TI of 1700– 2000ms achieves CSF suppression
31.
32. PARAMETERS
Long TI 1700– 2200ms (to suppress CSF depending on
field strength)
Long TE 70ms+(to enhance signal from pathology)
Long TR 6000 ms+ (to allow full recovery)
Long turbo factor 16– 20 (to enhance signal from
pathology)