This document discusses dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) techniques for measuring tissue perfusion. It describes how DCE-MRI analyzes the passage of gadolinium contrast agents through tissue over time to provide quantitative measurements of microvascular properties like permeability and blood flow. The document outlines the principles, image acquisition, and qualitative, semi-quantitative, and quantitative analysis methods for DCE-MRI. It also discusses applications for evaluating brain tumors and other disorders.
A comprehensive study about new and upcoming modalities in imaging and screening of breast lesions with description about every new modalities with their advantages and pitfalls.
A comprehensive study about new and upcoming modalities in imaging and screening of breast lesions with description about every new modalities with their advantages and pitfalls.
Everything regarding the physics of MRA is given along with flow charts and images. Also have covered new advances and refrences taken from MR made easy and some articles related to MRI
Magnetic Resonance Elastography is an advanced imaging technique in MRI. This method is a method of "virtual palpation" of internal organs with the help of MRI.
Everything regarding the physics of MRA is given along with flow charts and images. Also have covered new advances and refrences taken from MR made easy and some articles related to MRI
Magnetic Resonance Elastography is an advanced imaging technique in MRI. This method is a method of "virtual palpation" of internal organs with the help of MRI.
Unlike other modalities, MRI offers the capability to modulate both the emitted and received signals so that a multitude of tissue characteristics can be examined and differentiated without the need to change scanner hardware.
As a result, from a single imaging session, one could obtain a wealth of information regarding
cardiac function and morphology,
myocardial perfusion & viability,
hemodynamics,
large vessel anatomy.
CMR is now considered the gold standard for the assessment of regional and global systolic function, myocardial infarction (MI) and viability, and the assessment of congenital heart disease.
Physicians have used palpation to detect differences in tissue stiffness as an aid to diagnosis based on the fact that the mechanical properties of tissues are often dramatically affected by the presence of disease processes such as cancer, inflammation, and fibrosis. Elastography depends on the same differences in mechanical properties between healthy and abnormal tissues using imaging to detect these differences at depths not reachable by manual palpation and presents data in color-coded display, can be performed with ultrasound, using manual pressure or low frequency sonic waves, or by MR Elastography imaging.
SWI , high susceptibility for blood products, iron depositions, and calcifications
makes susceptibility-weighted imaging an important additional sequence for the diagnostic
workup of pediatric brain pathologic abnormalities. Compared with conventional MRI
sequences, susceptibility-weighted imaging may show lesions in better detail or with higher
sensitivity
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.
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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.
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
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
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Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
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.
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.
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.
2. Perfusion refers to the passage of blood from an arterial
supply to venous drainage through the microcirculation.
perfusion imaging provides hemodynamic information
that complements the anatomic information attainable
with conventional imaging.
3. Measurement of tissue perfusion depends on the ability to
serially measure concentration of a tracer agent in a target organ
of interest. Exogenous tracers such as iced saline solution,
iodinated radiographic contrast material, and radionuclides have
been used .
With the advent of MR imaging, exogenous tracer agents, such
as paramagnetic contrast material, and endogenous tracer
agents, such as magnetically labeled blood, have been used
5. Dynamic Susceptibility Contrast-
enhanced MR Perfusion
Exploits the T2* susceptibility effects of gadolinium,
rather than the T1 shortening effects routinely
associated with contrast enhancement on
conventional imaging.
Signal loss resulting from passage of the contrast agent
bolus on T2* weighted images can be used to calculate
the change in contrast concentration occurring in each
pixel
6.
7. Image acquisition
Comfortably positioned.
Data is acquired by using a fast imaging technique, such as single or multishot echo
planar imaging (EPI) to produce a temporal resolution of approximately 2 seconds.
The imaging sequence may be gradient echo which will maximize T2* weighting or
alternatively a spin echo approach can be used which will minimize the signal
contribution from large vessels.
A series of at least five pre-contrast images should be collected prior to the passage of the
bolus to improve the estimation of the signal intensity baseline during analysis.
A standard contrast dose (0.1 mmol/kg) is adequate in most cases although double dose
of gadolinium (0.2 mmol/Kg) may be used to improve signal to noise ratio.
The contrast is usually injected via an 18- or 20-gauge IV catheter at a high rate (3-7
mL/sec) using a power injector. The injection should be followed by a saline flush of at
least 25 mL (20-30 mL) in order to ensure that the bolus, which enters the central
circulation is as coherent as possible
8. Data analysis:
The drop in T2* signal caused by the susceptibility
effects of gadolinium is computed on a voxel-by-voxel
basis and used to construct a time-versus intensity
curve.
The degree of signal drop is then assumed to be
proportional to the tissue concentration of
gadolinium, so that relative concentration-time curves
can be obtained (delta R2 curves)
9. Figure shows data analysis in DSC perfusion. (A) Time-versus MR signal intensity curve where signal
intensity decrease during passage of contrast agent bolus and is measured from a series of MR
images. (B) Tissue concentration-versus time curve where change in the relaxation rate (ΔR2*) is
calculated from signal intensity, and a baseline subtraction method is applied to measured data. (C)
Corrected ΔR2* curve after leakage correction
10. To obtain tissue response function, arterial concentration-time curve, or
arterial input function, must be deconvolved from measured tissue
concentration-time curve. This arterial input function may be derived directly
from imaging data
11. Problems with DSC MRI:
Contrast recirculation
Contrast leakage and tissue enhancement
Bolus dispersion and the measurement of
absolute CBF
12. Dynamic Contrast Enhanced MR
Perfusion
provides insight into the nature of the tissue
properties at the microvascular level by demonstrating
the wash-in, plateau, and washout contrast kinetics of
the tissue.
also referred as ‘permeability’ MRI, is an entirely
different approach to MR perfusion as the main focus
is on estimating tumor permeability
13. main advantage of T1- based techniques is that tumor
leakiness (enhancement) is used for data analysis
rather than considering it as an artifact as in DSC MRP.
It has been established that quantification of contrast
leakage can provide powerful indicators of the state of
neovascular angiogenesis in pathologies, such as
tumors and inflammatory tissue;
14. Principle:
measures the ‘relaxivity effects’ of the paramagnetic
contrast material.
DCE MRP is based on a two-compartmental (plasma
space and extravascular-extracellular space)
pharmacokinetic model
15. Dynamic contrast-enhanced MR perfusion: Two-compartment model
demonstrates the exchange of contrast between plasma and extravascular-
extracellular space
16. Image acquisition:
perform baseline T1 mapping, acquire DCE MRP
images, convert signal intensity data to gadolinium
concentration, determine the vascular input function,
and perform pharmacokinetic modeling.
lower dose of gadolinium is administered (typically a
single dose of 0.1 mmol/kg) at a lower rate (2 mL/sec)
and repetitive acquisitions are then made through the
lesion at longer intervals, typically every 15 to 26
seconds
17. Data analysis:
Simple analysis techniques: comparing the signal
intensity curves from ROI.
simplest of these is a measurement of the time taken for
the tumor tissue to attain 90 percent of its subsequent
maximal enhancement (T90).
Various curve shapes can also provide insight into the
quantification and calculates a standardized slope of the
enhancement curve
18. Pharmacokinetic analysis techniques: several
metrics are commonly derived: the transfer constant
(ktrans), the fractional volume of the extravascular
extracellular space (ve), the rate constant (kep, kep =
ktrans/ve), and the fractional volume of the plasma
space (vp).
intended to calculate the biological features, such as
endothelial permeability and the endothelial surface
area, which are relatively independent of imaging
approach
19. Problems with quantitative
measurement of DCE MRI:
Partial volume averaging effects: excluding any
voxel which produces values over a certain threshold
(1.2/ min) as being vascular in origin or more complex
pharmacokinetic models.
Long acquisition time: modifying the
pharmacokinetic model and describing only the first
passage of the contrast bolus. This technique also
eliminates the problems with partial volume averaging
described above and produces highly reproducible
parametric maps of both ktrans and CBV.
20. Flow dependency of ktrans: in areas where there is
contrast leakage and the blood flow is inadequate to
replenish contrast at adequate rate; as a result plasma
contrast concentration decreases and ktrans will
reflect local blood flow.
21. Endogenous Tracer Methods Arterial Spin Labeling MR
Imaging
Arterial blood flowing towards the region of interest is
tagged by magnetic inversion pulses (proton phase is
changed).
↓
After a delay to allow for inflow of tagged blood,
image is acquired in slice of interest. This image is
called ‘tag image’.
↓
Second image without in-flowing tagged blood. This
image is called ‘control image’.
22. ↓
Tag image is subtracted from control image
↓
This results into perfusion image representing ‘tagged
blood’ that flowed into the image slice.
It has poor SNR, however, ASL has better spatial and
temporal resolution than PET. Poor SNR and
sensitivity to abnormally long transit delays of tagged
protons prevents its general application.
23.
24. APPLICATIONS
MR Perfusion in Stroke
Mismatch between PW and DW represent potentially
salvageable tissue (penumbra). PW-DW mismatch is
also indicator of clinical outcome. Small mismatch has
good clinical outcome. Large mismatch is associated
with poor clinical outcome and larger vessel occlusion.
30. Other disorders
In addition to evaluation of ischemia and tumors, MR perfusion
imaging has been applied to the study of various other neurologic and
psychiatric disorders, such as dementia and migraine headaches .
The effects of psychoactive drugs, such as cocaine, have been studied as
well (Kaufman MJ et al., presented at the International Society of
Magnetic Resonance in Medicine, April 1996).
In the case of migraine headaches, decreases in cerebral blood volume
and cerebral blood flow have been seen during the auras compared
with the post-aura state (Sorensen AG et al., presented at the
International Society of Magnetic Resonance in Medicine, April 1996).
In the case of dementia, decreases in cerebral blood volume in the
temporal and parietal lobes of patients with Alzheimer's disease have
correlated well with the results of SPECT studies on the same subjects
31. DYNAMIC CONTRAST-ENHANCED
MRI
malignant lesions usually show faster and higher levels
of enhancement than normal tissue. This
enhancement pattern of the malignant lesions reflects
increased vascularity (neoangiogenesis) and higher
endothelial permeability to the contrast molecules.
dynamic contrast-enhanced MRI (DCE-MRI) is
modality of choice for the diagnosis and
characterization of the tumors of the brain, breast,
prostate, liver, cervix and musculoskeletal system
32. Principle:
relies on fast MRI sequences obtained before, during
and after the rapid intravenous (IV) administration of
a gadolinium-based contrast agent.
DCE-MRI is sensitive to alterations in vascular
permeability, extracellular space and blood flow. The
DCE-MRI enables the depiction of physiologic
alterations as well as morphologic changes.
33. Image acquisition:
minimum of three sections
imaging volume that includes a region outside the tumor,
such as an artery or muscle for normalization.
injected at a constant rate with a power injector typically
using 3D T1-weighted acquisition.
Serial image sets are obtained sequentially every 5 seconds
(ranging from 2–15 seconds) for up to 5 to 10 minutes.
34. Data analysis:Qualitative or visual analysis is most readily
accessible analytic but also the least standardized method
35. Semi-quantitative analysis:
calculates various curve parameters and is also referred
as curveology.
also based on the assumption of early and intense
enhancement and washout as a predictor of
malignancy.
Parameters are obtained to characterize the shape of
the time-intensity curve, such as the time of first
contrast uptake, time to peak, maximum slope, peak
enhancement, and wash-in and washout curve shapes
36. There are three common dynamic curve types after
initial uptake: type 1, persistent increase; type 2,
plateau; and type 3, decline after initial upslope. Type 3
is considered to be indicator of malignancy.
semiquantitative approach is widely used and has the
advantage of being simple to perform
37. It has limitations in terms of generalization across
acquisition protocols, sequences, and all other factors
contributing to the MR signal intensity, which in turn
affect curve metrics, such as maximum enhancement
and washout percentage.
38. Quantitative analysis:
Quantitative analysis is most generalizable but most
complex method.
It depends on contrast concentration curves over time and
use pharmacokinetic models to calculate permeability
constants.
fundamental limitation of DCE-MRI, namely the
parameters it generates are inherently ambiguous with
regard to their physiologic significance.