Dr. Rajesh Venunath Nair teaches radiology at K.S Hegde Medical Academy in Mangalore. His presentation discusses the history, basic principles, hardware, imaging sequences, and clinical applications of magnetic resonance imaging (MRI). It explains how MRI uses radiofrequency pulses and magnetic fields to produce detailed images of internal organs and soft tissues without using ionizing radiation. The presentation covers the main components of MRI scanners, different pulse sequences, tissue contrast mechanisms, use of contrast agents, safety considerations, and recent technical advances that have expanded clinical use of MRI.
basic and brief but informative knowledge about how MRI works and what are its components ... easy to understand as well as presenting during lectures and in classes . share it
Computed tomography (CT scan) is a medical imaging procedure that uses computer-processed X-rays to produce tomographic images or 'slices' of specific areas of the body. These cross-sectional images are used for diagnostic and therapeutic purposes in various medical disciplines.
Brief explanation of what is PET, the main components for a PET system along with their basic functions. The principle behind PET inclusive of positron emission and emission detection. Acquisition and reconstruction of the collected data to produce the final image. Finally the pros and cons of Positron emission tomography.
Magnetic resonance imaging (MRI) is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body
basic and brief but informative knowledge about how MRI works and what are its components ... easy to understand as well as presenting during lectures and in classes . share it
Computed tomography (CT scan) is a medical imaging procedure that uses computer-processed X-rays to produce tomographic images or 'slices' of specific areas of the body. These cross-sectional images are used for diagnostic and therapeutic purposes in various medical disciplines.
Brief explanation of what is PET, the main components for a PET system along with their basic functions. The principle behind PET inclusive of positron emission and emission detection. Acquisition and reconstruction of the collected data to produce the final image. Finally the pros and cons of Positron emission tomography.
Magnetic resonance imaging (MRI) is a type of scan that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body
MRI is an imaging technique that uses strong magnetic fields and radio waves to create detailed images of the human body. It is primarily used in medical settings to get high-resolution images of the inside of the human body. MRI is also used to monitor the effectiveness of certain medical treatments, such as surgery and radiation therapy.
Please have a look at the features and Images from our latest installation of MDT centauri 3000 OPEN MRI systems at Chirayu Hospital, Ratnagiri, India.
This presentation discusees a brief history of the MRI, it's mechanism of action, applications in dentistry and recent advancements in its technology. Also it's advantages and disadvantages in comparison with the CT scan
Multiparametric Quantitative MRI as a Metric for Radiation Treatment PlanningCrimsonpublishersCancer
Magnetic resonance imaging (MRI) provides excellent soft tissue contrast, and in combination with its quantitative functional imaging capability, this modality is ideal for use in radiotherapy. MRI images, either used directly or fused with CT, play an increasingly important role in contouring gross tumor volume (GTV) and organs at risk (OAR) in radiation treatment planning (RTP) systems. The soft tissue contrast of MRI images provides more accurate tumor delineation than CT, although CT images have sufficient geometrical stability and electron density information for accurate radiation treatment planning. Many vendors now offer 70 cm wide-bore MRI systems with dedicated radiofrequency (RF) coils and immobilization devices for RTP simulation comparable to CT simulators.
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.
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
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
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.
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.
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.
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.
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
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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
1. Dr. Rajesh Venunath Nair
Assistant Professor
Department of Radiodiagnosis
K.S Hegde Medical Academy, Mangalore
2.
3. Objectives
To know the history behind the discovery of magnetic
resonance imaging.
To understand the principles of MR imaging and the
steps and basic physics behind image acquisition.
To understand the basic hardware and soft ware
involved in MR imaging.
To elaborate the advantages, disadvantages and uses of
MRI.
To understand the safety issues associated with MRI.
To familiarize with the latest application of MRI.
11. Types of MR Scanners
Open MRI – Low Magnetic field strength made of
permanent magnets
Closed MRI – Superconducting magnets of high field
strength.
18. Types of RF Coils
Volume coils – Head coil, Body coil, Spine coil.
Surface coils
Phase array coils.
Surface coils produce high resolution images but the field
of view is small.
Body coils have larger field of view.
RF coils can be receiving only, transmitting only or
combined receiving and transmitting coils.
RF pulses commonly used are 90 and 180 degree pulses.
30. The emitted energy of the protons
once the RF is stopped is affected by
in which tissue (the “lattice”) it
resides: fat, muscle, ligament, bone,
brain, etc.
31. RF Pulse sequence parameters
which the technician adjusts
The three pulse sequence parameters are
Repetition time (TR) measured in msec ie the time to repeat the RF
pulse.
Echo time (TE) measured in msec ie the time to receive the signal.
Time to invert(TI) ie the time to sent the 180degree inversion pulse.
Flip angle measured in degrees ie the degree to which the spinning
protons are flipped from the horizontal axis.
32.
33.
34. T1 and T2 relaxation times
Occur simultaneously and
independently of each other and
form
the basis of tissue contrast in MR-
reconstructed images
35. T1
• Low TR (400-700 msec)
• Low TE (20-40 msec)
T2
• High TR (2,000-3,000 msec)
• High TE (40-70 msec)
Proton density
• High TR (2,000-3,000msec)
• Low TE (20-40 msec)
36. Basic Sequences
T1 to view anatomy
T2 to detect a pathologic process
(edema, swelling)
Proton Density (PD)
great for ligamentous anatomy
37.
38.
39. Basic Pulse Sequences for MRI Imaging
Image type Fat Water Advantage
T1 Bright Dark Anatomical detail
T2 Intermediate Bright ++ edema
Fat
Suppressed
T2
Very Dark Very Bright ++++ edema
40.
41.
42. Advantages of MRI
Lack of ionizing radiation – used in pediatric and
obstetric imaging.
Better soft tissue contrast resolution.
Multiplanar imaging capabilities.
Does not use iodinated contrast agents.
Safe in patients with renal failure.
43. Disadvantages of MRI
Expensive.
Longer scanning time.
Susceptible to movement artifacts.
Cannot be used in acute trauma settings.
Does not image the bone and lungs.
Scanner not available at all places.
Requires skilled technicians for operating and
maintenance cost is high.
44. Indications for MR Imaging
Diagnosis of Brain and Spinal cord diseases.
Staging of cancers like rectum, cervix and prostate.
Diagnosis of musculoskeletal pathologies of knee, hip
and shoulder.
Imaging of spine and intervertebral discs.
Fetal MRI to detect anomalies.
Cardiac MRI for assessment of myocardium.
Breast MRI for diagnosing breast lesions.
45. Contraindications for MRI
Absolute:
Patients with cardiac pacemaker or defibrillator.
Patients with intraoccular metallic foreign bodies.
Patients with cochlear implants.
Patients with stainless steel metallic implants.
Patients with souvenir bullets.
Relative:
Claustrophobic patients.
Patients with Insulin Pump.
Patients with knee and hip prosthesis.
47. MRI Contrast Agent
Gadolinium chelates are the commonly used MRI contrast
agenta and the next being Manganese. They are
paramagnetic elements with atomic number 64 with 7
unpaired electrons.
It reduces the T1 relaxation time of protons and increases
the signal intensity on T1WI.
Given as intravenous agents at dose of 0.1mg/k, they are
intravascular agents that improves the conspicuity of
lesions which further aids in confirming the diagnosis.
Usually viewed in T1 weighted fat suppressed images in
multiplanar sections.
Side Effects – Nausea Vomiting, Anaphylaxis and Seizures.
50. Uses of Gadolinium
MR Arthrography.
Enhancement of tumor masses and inflammatory
abscess.
MR Urography.
Contrast Enhanced MR Angiography.
Dreaded complication of long term gadolinium use is
nephrogenic systemic fibrosis in patients with renal
failure and reduced GFR.
55. Recent Advances in MRI
Diffusion weighted images based on the restricted
movement of water protons, useful in the diagnosis of
stroke and tumors of brain.
MR Spectroscopy – Non invasive method to assess the
metabolites in tissues based on the spin of protons
within each metabolite.
Functional MRI – gives information about the
functional activity of different parts of brain using
BLOD sequence.
MRI guided biopsy.
The magnet is a huge super-cooled one
The absorption and release of electromagnetic energy by hydrogen protons while in the magnetic field is the ‘resonance”
The computer receives the signal from the spinning protons as mathematical data; the data is converted into a picture through the Fournier transform mathematical formula. That’s the "imaging" part of MRI.
Nuclear magnetic resonance (NMR) is a physical phenomenon which magnetic nuclei in a magnetic field
absorb and re-emit electromagnetic radiation.
The RF used in MRI are the same range as in common radio communication. These are non ionizing radiation unlike used in conventional x-ray and CT scans. How the common radio works can take some of the mystery out of how MRI images are generated.
Like X ray, MRI is based on a discovery in the physic lab: when the nuclei of hydrogen atoms--single protons, all spinning randomly--are caught suddenly in a strong magnetic field, they tend to line up like so many compass needles. If the protons are then hit with a short, precisely tuned burst of radio waves, they will momentarily flip around. Then, in the process of returning to their original orientation, they resound with a brief radio signal of their own that announces the presence of a specific tissue. The intensity of this emission reflects the number of protons in a particular "slice" of matter
When patients slide into an MRI machine, they take with them the billions of atoms that make up the human body. For the purposes of an MRI scan, we're only concerned with the hydrogen atom, which is abundant since the body is mostly made up of water and fat. These atoms are randomly spinning, or precessing, on their axis, like a child's top. All of the atoms are going in various directions, but when placed in a magnetic field, the atoms line up in the direction of the field.
When a strong magnetic field is applied*.
These hydrogen atoms have a strong magnetic moment, which means that in a magnetic field, they line up in the direction of the field. Since the magnetic field runs straight down the center of the machine, the hydrogen protons line up so that they're pointing to either the patient's feet or the head. About half go each way, so that the vast majority of the protons cancel each other out -- that is, for each atom lined up toward the feet, one is lined up toward the head. Only a couple of protons out of every million aren't canceled out. This doesn't sound like much, but the sheer number of hydrogen atoms* in the body is enough to create extremely detailed images. It's these unmatched atoms that we're concerned with now.
*Measured in teslas on the order of 0.5 to 3.0 (the earth’s magnetic field strength is 10 thousand time less than this (T 1.5 tesla or 15000 gauss vs Earth 0.5 gauss)
**There are 4.7 x 10 to the 27th power hydrogen protons in the human body, more than the est. stars in the Universe. One in a million means 10 to the 21th power protons do not align and are subjects of the RF
the MRI machine applies a radio frequency (RF) pulse that is specific only to hydrogen. The system directs the pulse toward the area of the body we want to examine. When the pulse is applied, the unmatched protons absorb the energy and spin again in a different direction. This is the "resonance" part of MRI. The RF pulse forces them to spin at a particular frequency, in a particular direction. The specific frequency of resonance is called the Larmour frequency and is calculated based on the particular tissue being imaged and the strength of the main magnetic field.
It is during the time between the radiofrequency turned off to return to normal position that energy signals are generated which can be detected and transferred to a computer.
By a series of calculations using the Fourier transform equations, the individual radio frequencey amplitutes are given a number (digitalized).
The value of those numbers (brightness of the dots) dictate how bright the wave that that point represents should be plotted on the MR image. Now were getting down to the point: an MR image is simply the superposition of thousands of these waves, all plotted on the same image, one o top of the another. When you add them all together, you get the image (like the shoulder in this example). It sounds improbable, but its true. Perhaps MRI should stand for Magical Remarkable Images.
We will concentrate on 3 series of MRIs: T1, T2, T2 fat suppressed and Proton Density as seen in all three cardinal planes
The flip angle a is used to define the angle of excitation for a field echo pulse sequence. It is the angle to which the net magnetization is rotated or tipped relative to the main magnetic field direction via the application of a RF excitation pulse at the Larmor frequency. It is also referred to as the tip angle, nutation angle or angle of nutation. The radio frequency power (which is proportional to the square of the amplitude) of the pulse is proportional to a through which the spins are tilted under its influence. Flip angles between 0° and 90° are typically used in gradient echo sequences, 90° and a series of 180° pulses in spin echo sequences and an initial 180° pulse followed by a 90° and a 180° pulse in inversion recovery sequences.
Students are given this hand out which is also posted on the CHA website
Modified from: Khanna AJ, Cosgarea AJ, Mont MA, Andres BM, Domb BG, Evans PJ, Bluemke DA, Frassica FJ. Magnetic resonance imaging of the knee. Current techniques and spectrum of disease. J Bone Joint Surg Am. 2001;83 Suppl 2(Pt 2):129. In STIR sequences, the echo time is varied to make the water appear bright (i.e., a fluid-sensitive sequence).
Confusing terminology:
The term Proton Density is actually an inaccurate term, as it implies that the only contrast mechanism of the image is based on differences in proton density. In fact, contrast is predominantly derived from intermediate weighting between T1 and T2. Most, so called PD sequences have TRs that are too short to completely eliminate T1 contrast and TEs that are too long to completely eliminate T2 contrast.
There are a multitude of other sequences STIR, Flair with more on the way as newer MRIs have increased magnetic flux density(tesla) from stronger magnets in the units.