This document discusses various types of artifacts that can occur in MRI imaging, including equipment-related artifacts like non-uniform signal and phase wrap, as well as patient-related artifacts like susceptibility effects and motion blurring. It provides examples of static magnetic field (B0) inhomogeneity artifacts caused by differences in magnetic susceptibility between tissues. The document also discusses specific artifact reduction strategies, such as improving B0 field shimming, adjusting pulse sequence parameters like echo time, and using parallel imaging techniques to reduce geometric distortion from susceptibility effects. In summary, the document provides an overview of common MRI artifacts and their causes, with a focus on artifacts from magnetic field inhomogeneities and susceptibility differences between tissues.
Basic physics of multidetector computed tomography ( CT Scan) - how ct scan works, different generations of ct, how image is generated and displayed and image artifacts related to CT Scan.
Basic physics of multidetector computed tomography ( CT Scan) - how ct scan works, different generations of ct, how image is generated and displayed and image artifacts related to CT Scan.
MDCT Principles and Applications- Avinesh ShresthaAvinesh Shrestha
Multidetector CT (MDCT) is one of the most commonly used imaging modality in the field of Radiology. Development and advancement in MDCT has made it's application as a major component in diagnosis and treatment planning of multitude of disease across the planet. This presentation briefly describes its basic principle and it's wide variety of application in medical imaging.
This presentation includes High-resolution computed tomography (HRCT) of the Chest and Temporal bone.
Objective of HRCT.
Artefacts in HRCT.
Clinical applications of HRCT.
Advantages of HRCT.
Disadvantages of HRCT.
Positioning and Centering.
MDCT Principles and Applications- Avinesh ShresthaAvinesh Shrestha
Multidetector CT (MDCT) is one of the most commonly used imaging modality in the field of Radiology. Development and advancement in MDCT has made it's application as a major component in diagnosis and treatment planning of multitude of disease across the planet. This presentation briefly describes its basic principle and it's wide variety of application in medical imaging.
This presentation includes High-resolution computed tomography (HRCT) of the Chest and Temporal bone.
Objective of HRCT.
Artefacts in HRCT.
Clinical applications of HRCT.
Advantages of HRCT.
Disadvantages of HRCT.
Positioning and Centering.
A review of advances in Brachytherapy treatment planning and delivery in last decade or so, with main focus on brachytherapy for Prostate cancer, Breast cancer and Cervical cancer
MRI artifacts remains a big challenge to get a diagnostic image. This represents a practical comprehensive approach to understand MRI artifacts & how to get rid of.
Magnetic resonance imaging (MRI) is a medical imaging technique that uses a magnetic field and computer-generated radio waves to create detailed images of the organs and tissues in your body.
Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily realigns water molecules in your body. Radio waves cause these aligned atoms to produce faint signals, which are used to create cross-sectional MRI images — like slices in a loaf of bread.
The MRI machine can also produce 3D images that can be viewed from different angles.
Products & Services
Sign up for Email: Get Your Free Resource – Coping with Cancer
Why it's done
MRI is a noninvasive way for your doctor to examine your organs, tissues and skeletal system. It produces high-resolution images of the inside of the body that help diagnose a variety of problems.
MRI of the brain and spinal cord
MRI is the most frequently used imaging test of the brain and spinal cord. It's often performed to help diagnose:
Aneurysms of cerebral vessels
Disorders of the eye and inner ear
Multiple sclerosis
Spinal cord disorders
Stroke
Tumors
Brain injury from trauma
A special type of MRI is the functional MRI of the brain (fMRI). It produces images of blood flow to certain areas of the brain. It can be used to examine the brain's anatomy and determine which parts of the brain are handling critical functions.
This helps identify important language and movement control areas in the brains of people being considered for brain surgery. Functional MRI can also be used to assess damage from a head injury or from disorders such as Alzheimer's disease.
MRI of the heart and blood vessels
MRI that focuses on the heart or blood vessels can assess:
Size and function of the heart's chambers
Thickness and movement of the walls of the heart
Extent of damage caused by heart attacks or heart disease
Structural problems in the aorta, such as aneurysms or dissections
Inflammation or blockages in the blood vessels
Magnetic resonance imaging (MRI) is a medical imaging technique that uses a magnetic field and computer-generated radio waves to create detailed images of the organs and tissues in your body.
Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily realigns water molecules in your body. Radio waves cause these aligned atoms to produce faint signals, which are used to create cross-sectional MRI images — like slices in a loaf of bread.
The MRI machine can also produce 3D images that can be viewed from different angles.
Products & Services
Sign up for Email: Get Your Free Resource – Coping with Cancer
Why it's done
MRI is a noninvasive way for your doctor to examine your organs, tissues and skeletal system. It produces high-resolution images of the inside of the body that help diagnose a variety of problems.
MRI of the brain and spinal cord
MRI is the most frequently used imaging test of the brain and spinal cord. It's often performed to help diagnose:
Aneurysms of cerebral vessels
Disorders of the eye and inner ear
Multiple sclerosis
Spinal cord disorders
Stroke
Tumors
Brain injury from trauma
A special type of MRI is the functional MRI of the brain (fMRI). It produces images of blood flow to certain areas of the brain. It can be used to examine the brain's anatomy and determine which parts of the brain are handling critical functions.
This helps identify important language and movement control areas in the brains of people being considered for brain surgery. Functional MRI can also be used to assess damage from a head injury or from disorders such as Alzheimer's disease.
MRI of the heart and blood vessels
MRI that focuses on the heart or blood vessels can assess:
Size and function of the heart's chambers
Thickness and movement of the walls of the heart
Extent of damage caused by heart attacks or heart disease
Structural problems in the aorta, such as aneurysms or dissections
Inflammation or blockages in the blood vessels
Muktapishti is a traditional Ayurvedic preparation made from Shoditha Mukta (Purified Pearl), is believed to help regulate thyroid function and reduce symptoms of hyperthyroidism due to its cooling and balancing properties. Clinical evidence on its efficacy remains limited, necessitating further research to validate its therapeutic benefits.
Basavarajeeyam is a Sreshta Sangraha grantha (Compiled book ), written by Neelkanta kotturu Basavaraja Virachita. It contains 25 Prakaranas, First 24 Chapters related to Rogas& 25th to Rasadravyas.
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
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
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!
CDSCO and Phamacovigilance {Regulatory body in India}NEHA GUPTA
The Central Drugs Standard Control Organization (CDSCO) is India's national regulatory body for pharmaceuticals and medical devices. Operating under the Directorate General of Health Services, Ministry of Health & Family Welfare, Government of India, the CDSCO is responsible for approving new drugs, conducting clinical trials, setting standards for drugs, controlling the quality of imported drugs, and coordinating the activities of State Drug Control Organizations by providing expert advice.
Pharmacovigilance, on the other hand, is the science and activities related to the detection, assessment, understanding, and prevention of adverse effects or any other drug-related problems. The primary aim of pharmacovigilance is to ensure the safety and efficacy of medicines, thereby protecting public health.
In India, pharmacovigilance activities are monitored by the Pharmacovigilance Programme of India (PvPI), which works closely with CDSCO to collect, analyze, and act upon data regarding adverse drug reactions (ADRs). Together, they play a critical role in ensuring that the benefits of drugs outweigh their risks, maintaining high standards of patient safety, and promoting the rational use of medicines.
The Gram stain is a fundamental technique in microbiology used to classify bacteria based on their cell wall structure. It provides a quick and simple method to distinguish between Gram-positive and Gram-negative bacteria, which have different susceptibilities to antibiotics
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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
2. MRI Gradient fields
• The gradient fields are superimposed over the static
magnetic field. For transverse images:
• Z gradient–selects the slice, and is applied whilst the 90° RF
pulse is on
• X gradient–creates a frequency change in emitted signal
producing lines (or columns) of data, and is applied when
the echo RF is being measured
• Y gradient–produces a change in the phase of rotation in
different voxels, and is applied between the 90° and 180°
RF pulses at a different strength during each cycle. The
number of phase steps (e.g. 256) affects scan time.
• “Frequency encoding” and “Phase encoding” directions (X
and Y) are interchangeable.
4. MRI distortion Artifacts
A whole range……..
Equipment-related
• Non-uniformity of signal
• Wraparound (phase wrap,
aliasing)
• Peripheral signal artifacts
• Slice overlap (cross-excitation)
• Noise and RF interference
• Truncation (ringing, Gibbs
artifact)
• Phase smearing
Patient-related
• Signal void due to freezing
• Partial volume averaging
• Chemical shift
• Motion artifacts (blurring,
ghosting and pulsatility)
• Flow artifacts
• Susceptibility and image
distortion
• Magic angle
5. B0 inhomogeneity and susceptibility
• Extremely homogeneous static magnetic field is required
around isocenter of the magnet for MRI.
• B0 homogeneity of the empty magnet:
typical value of 1ppm (0.001%) in a 50 cm diameter
spherical volume.
• susceptibility = local changes in Bo due to a substance’s
own magnetic properties
• Artifacts occur at interfaces between substances of different
susceptibilities, e.g. air/bone/metal/ calcification/hemorrhage;
implants and previous surgery, tooth fillings, mascara, ear-rings,
hair-slides
– worse at higher field strengths
6. B0 inhomogeneity
• Decreased frequency-selective fat-saturation efficacy of pulses
• Effect more pronounced the further the image slice is positioned from
the isocenter of the magnet
(a) off-center acquisition with insufficient fat
suppression (arrows)
(b) Identical acquisition at isocenter
Reduction:
improve field shimming
Optimal positioning of the patient in z-direction
Dietrich et. al., Artifacts in 3-T MRI: Physical background and reduction strategies, EJR, 65, 2008
7. B0 inhomogeneity
•
Relatively small frequency shifts lead to substantial reduction of the
transversal steady-state magnetization and, thus, to band-shaped signal losses
in the image
Reduction:
Move the artifact out of the region of interest (apply frequency offset to nominal
resonant frequency)
Dietrich et. al., Artifacts in 3-T MRI: Physical background and reduction strategies, EJR, 65, 2008
8. Susceptibility: Metal artifacts
•
An important manifestation of a susceptibility-related artifact is the signal
loss in gradient-echo images around metallic implants or surgical clips
Right hip prosthesis is seen as region of signal drop
out (closed arrows)
Figure from: Mechlin et al, AJR 143, December 1984
STIR axial MRI image of a patient, arrows B point to
artifacts due to right hip prosthesis.
Figure from: Dr. Geller et al, Malignant Peripheral Nerve
Sheath Tumors (MPNST), ESUN, june 2006, 3(3)
http://sarcomahelp.org/learning_center/mpnst.html
Reduction:
Decrease Echo time, TE, of pulse sequence
Increase receiver band-width
9. Susceptibility: Geometric distortion
artifact
•
•
Usually in echo-planar imaging (EPI)
At interfaces between soft-tissue and bone/air e.g., in the
base of the skull or in the head-and-neck region
Reduction:
a) decrease the echo-spacing of the
read out train e.g., by increasing
the receiver bandwidth or by
parallel imaging techniques
b) Use fast-spin echo technique
(b) EPI acquisition without parallel imaging, severe distortion
artifacts are visible (arrows) and (c) EPI acquisition with
acceleration factor 2, distortion artifacts are still present but
considerably reduced (arrows).
Dietrich et. al., Artifacts in 3-T MRI: Physical background and reduction strategies, EJR, 65,
2008
10. B1 inhomogeneity
• Spatial inhomogeneity of the B1 field results in
flip-angle deviations depending on the spatial
position
• Reduced signal intensity in these areas or to
altered contrast particularly in FLASH sequences
whose T1-weighting depends on the flip angle
11. Dielectric resonance effects/ RF
interference/ standing wave effect
•
Constructive or destructive interferences of the transmitted RF field may be observed
resulting in either regional (e.g., central) brightening or regional signal loss,
respectively.
Signal loss due to wavelength effect
Reduction:
a) Effect can be mitigated by positioning a dielectric cushion close to the ROI, or
b) Manually modify the RF-transmitter amplitude in order to reduce B1-inhomogeneityinduced signal loss
12. Chemical Shift Artifact
• For MRI in vivo, two important groups of
molecules : protons in water and protons in
fat tissue.
• Larmor frequencies difference of these
protons ~ 3.5 ppm.
• chemical shift leads to a slight geometric shift
of the relative position of water and fat
protons in readout direction.
13. Chemical Shift Artifact Reduction
image-compromising superposition of
fat tissue onto other tissues
Reduction:
a)manually increase the RF-transmitter amplitude and apply image post-processing
filters to obtain more uniform image intensities.
b)Increase (~double) receiver bandwidth
c)Based on anatomy switch readout and phase encoding directions
14. Blood Flow related artifact
• Magnetohydrodynamic effect: The flow of blood ions
perpendicular to the strong static magnetic field, B0, gives rise to
induced voltages and currents;
“(a) Signal loss in the pulmonary vessels in non-gated 3-T single-shot fast-spin-echo
(FSE) acquisition possibly related to the magnetohydrodynamic effect. (b) Non-gated
1.5-T single-shot FSE acquisition demonstrating visual signal in pulmonary vessels. (c)
ECG-gated 3-T single-shot FSE acquisition of the same volunteer as in (a) with data
acquisition during diastole; the vessel signal is restored.” …….Deitrich et al, EJR
65(2008)
15. SNR related artifacts
• Artifacts to Noise ratio (ANR)
• Artifacts are masked by increased statistical
noise.
• Gibbs Ringing: caused by data clipping at the
edges of K-space (raw data readings are still over
noise level at the borders of acquired K-space)
17. Resources
Many more Artifacts but time restriction
⇒Resources for MR Artifacts ad their reduction
⇒MR-TIP: online database (open forum) from University
of Illinois, Excellent resource
⇒ Review article by Dietrich et.al,”Artifacts in 3-T MRI:
Physical Background and reduction strategies” EJR, Vol
65, 2008