2.comprehensive written report (mri)

7/24/2019 2.Comprehensive Written Report (MRI)

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Polytechnic University of the Philippines

Sta. Mesa, Manila

College of Engineering

Department of Electronics and Communication Engineering

MRI- Magnetic Resonance Imaging

Barrion, John Ervin M.

Gopez, Jayson B.

Sto. Domingo, Joziel R.

(Researchers)

BSECE IV-2


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Engr. Marianito P. Gallego Jr.

(Professor)

MRI- Magnetic Resonance Imaging

I. Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is a noninvasive medical test that helps

physicians diagnose and treat medical conditions. MRI uses a powerful

magnetic field, radio frequency pulses and a computer to produce detailed

pictures of organs, soft tissues, bone and virtually all other internal body

structures. MRI does not use ionizing radiation (x-rays).

Detailed MR images allow physicians to evaluate various parts of the body

and determine the presence of certain diseases. The images can then be

examined on a computer monitor, transmitted electronically, printed or

copied to a CD. It is based on the principles of nuclear magnetic resonance

(NMR), a spectroscopic technique to obtain microscopic chemical and

physical information about molecules. MRI has advanced beyond a

tomographic imaging technique to a volume imaging technique.

Magnetic resonance imaging (MRI) is a test that uses a magnetic field and

pulses of radio wave energy to make pictures of organs and structures

inside the body. In many cases, MRI gives different information about

structures in the body than can be seen with anX-ray,ultrasound,
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orcomputed tomography (CT) scan. MRI also may show problems that

cannot be seen with other imaging methods.

For an MRI test, the area of the body being studied is placed inside a

special machine that contains a strong magnet. Pictures from an MRI scan

are digital images that can be saved and stored on a computer for more

study. The images also can be reviewed remotely, such as in a clinic or an

operating room. In some cases,contrast materialmay be used during the

MRI scan to show certain structures more clearly.

You may be able to have an MRI with anopen machinethat doesn't

enclose your entire body. But open MRI machines aren't available

everywhere. The pictures from an open MRI may not be as good as those

from astandard MRI machine.

MRI can give different information about structures in the body than can

be obtained using a standard x-ray, ultrasound, or computed tomography

(CT) exam. For example, an MRI exam of a joint can provide detailed images

of ligaments and cartilage, which are not visible using other study types. In

some cases, a magnetically active material (called a contrast agent) is used

to show internal structures or abnormalities more clearly.

In most MRI devices, an electric current is passed through coiled wires to

create a temporary magnetic field around a patients body. (In open-MRI

devices, permanent magnets are used.) Radio waves are sent from and

received by a transmitter/receiver in the machine, and these signals are

used to produce digital images of the area of interest.
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An MRI (or magnetic resonance imaging) scan is a radiology technique that

uses magnetism, radio waves, and a computer to produce images of body

structures. The MRI scanner is a tube surrounded by a giant circular

magnet. The patient is placed on a moveable bed that is inserted into the

magnet. The magnet creates a strong magnetic field that aligns the protons

of hydrogen atoms, which are then exposed to a beam of radio waves. This

spins the various protons of the body, and they produce a faint signal that

is detected by the receiver portion of the MRI scanner. The receiver

information is processed by a computer, and an image is produced.

The image and resolution produced by MRI is quite detailed and can detect

tiny changes of structures within the body. For some procedures, contrast

agents, such as gadolinium, are used to increase the accuracy of the

images.

II. History

Magnetic resonance imaging (MRI) is a sophisticated imaging technique

that has evolved as a clinical modality over the past 30 years. The origins of

MRI, or NMR (nuclear magnetic resonance), as it was termed in the past,

however, can be traced back for over a century. Along the way, many

scientists from diverse disciplines have made remarkable contributions that

have brought the field to its present statea clinical tool capable of real

time in-utero cardiac imaging and a research tool capable of imaging a

single cell. As this powerful imaging modality and scientific tool continues

to evolve, it is worthwhile to pause and look back at the evolution of MRI


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and note the scientists who made the extraordinary contributions that have

led to five Nobel Prizes awarded to discoveries related to NMR/MRI.

By 1975, Peter Mansfield and Andrew Maudsley proposed a line scan

technique, which, in 1977, led to the first image of in vivo human anatomy,

a cross section through a finger. In 1977, Hinshaw, Bottomley, and Holland

succeeded with an image of the wrist and Damadian et al. created a cross

section of a human chest. More human thoracic and abdominal images

followed, and, by 1978, Hugh Clow and Ian R. Young, working at the British

company EMI, reported the first transverse NMR image through a human

head. Two years later, William Moore and colleagues presented the first

coronal and sagittal images through a human head. In 1980, Edelstein et

al. from Aberdeen University in Scotland demonstrated imaging of the body

using Ernsts technique. A single image could be acquired in approximately

five minutes by this technique. By 1986, the imaging time was reduced to

about five seconds without sacrificing too much image quality.

A.Quick History of the MRI

1882 Nikola Tesla discovered the Rotating Magnetic Field in Budapest,

Hungary. This was a fundamental discovery in physics.

1937 Columbia University Professor Isidor I. Rabi working in the Pupin

Physic Laboratory in New York City, observed the quantum phenomenon

dubbed nuclear magnetic resonance (NMR). He recognized that the atomic

nuclei show their presence by absorbing or emitting radio waves when

exposed to a sufficiently strong magnetic field.


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1946 Felix Bloch and Edward Purcell discover magnetic resonance

phenomenon.

1950s Herman Carr creates a one-dimensional MR image.

1956 The "Tesla Unit" was proclaimed in the Rathaus of Munich, Germany

by the International Electro-technical Commission-Committee of Action. All

MRI machines are calibrated in "Tesla Units". The strength of a magnetic

field is measured in Tesla or Gauss Units. The stronger the magnetic field,

the stronger the amount of radio signals which can be elicited from the

body's atoms and therefore the higher the quality of MRI images.

1969 Original Concept; Damadian Conceives of and proposes whole body

MR scanner for the first time.

1970 - Key Discovery Makes MR Scanner Possible; Damadian identifies

T1/T2 differences between cancer and normal. He was seeking an MR

signal difference in an important disease (cancer) that would prove his idea

of an MR body scanner was a goal worth pursuing.

March 1971 First Published Article; Damadian T1/T2 findings and

scanner proposal published inScience, March 19, 1971. High pixel contrast

provided by dramatic T1/T2 differences overcomes x-ray's century-old

inability to see detail in vital organs.

Spring 1971 Scanning Method Proposed; Damadian outlines voxel-by-voxel

scanning method

September 1971 Gradient Method Proposed; Lauterbur notebook proposal

of gradient methods of Gabillard, Purcell & Carr for 1-dimension


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1971 Raymond Damadian, a physician and experimenter working at

Brooklyn's Downstate Medical Center discovered that hydrogen signal in

cancerous tissue is different from that of healthy tissue because tumors

contain more water. More water means more hydrogen atoms. When the

NMR machine was switched off, the bath of radio waves from cancerous

tissue will linger longer then those from the healthy tissue.

1972 MRI adapted for medical purposes; Using highspeed computers,

magnetic resonance imaging (MRI) is adapted for medical purposes, offering

better discrimination of soft tissue than xray CAT and is now widely used

for noninvasive imaging throughout the body. Among the pioneers in the

development of MRI are Felix Bloch and Edward Purcell (Nobel Prize

winners in 1952), Paul Lauterbur, and Raymond Damadian.

March 1972 First Patent Filed; Damadian files '832 patent for 3-dimension

voxel-by-voxel scan method and T1/T2 method.

October 1972 2D Scan (Image) Achieved; Lauterbur submits 2-dimension

MR scan (image) method with scan of 1mm tubes for publication

1972 Raymond Damadian applies for a patent, which describes the concept

of NMR being used for above purpose. He illustrates major parts of MRImachine in his patent application.

March 1973 2D Paper Published; Lauterbur paper published in Nature,

March 16, 1973


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1973 Paul Lauterbur, a chemist and an NMR pioneer at the State University

of New York, Stony Brook, produced the first NMR image. It was of a test

tube.

1974 3D Scan Method Proposed; Garroway, Grannell & Mansfield publish

3-dimension scan method

1974 Raymond Damadian receives his patent.

1975 Phase Coding Introduced; Kumar, Welti & Ernst introduce phase

encoding to scan method

1975 Richard Ernst proposes using phase and frequency encoding and

Fourier transform for acquisition of MR images.

1977 First Human Scan Achieved; Damadian and coworkers, Minkoff and

Goldsmith, achieve first scan (image) of the human body utilizing voxel

method of patent.

1977 Raymond Damadian produces MR image of the whole body. Peter

Mansfield improves mathematics behind MRI and develops echo-planar

technique, which allows images to be produces in seconds and later

becomes the basis for fast MR imaging.


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Figure 1. On July 3, 1977, nearly

five hours after the start of

the first MRI test, the first human

scan was made as the first MRI prototype.

The image above is of Dr. Damadian with the

history- making prototype of

his MRI scanner. This prototype is now on

permanent display at the Smithsonian Institutions Hall of Medical Sciences.

1980Phase Coding Applied; Aberdeen group introduces spin warp method

1980 Phase Coding Applied; Aberdeen group introduces spin warp method

1983 Ljunggren and Tweig introduce k-space.

1986 Le Bihan publishes an article in Radiology, which describes diffusion

weighted imaging (DWI).


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1987 Real time MR imaging of the heart is developed.

1991 Filler and colleagues describe imaging of axonal transport of

supermagnetic metal oxide particles, a technique, which later becomes

important in imaging of neural tracts.

1993 Functional MR imaging of the brain is introduced.

1994 The first intraoperative MR unit developed by GE and Harvard is

installed in the Brigham and Women's Hospital in Boston.

1997 Patent Upheld; High Court on U.S. Patents and U.S. Supreme Court

enforce Damadian '832 patent.

1990s In addition to research centers and large hospitals, small remote

hospitals and imaging centers begin to utilize MRI predominantly for

neuroimaging and musculoskeletal imaging.

2000s Cardiac MRI, Body MRI, fetal imaging, functional MR imaging are

further developed and become routine in many imaging centers. Research

centers make significant strides forward in imaging cartilage on high field

scanners. The number of free standing MRI centers, most of which utilize

low or moderate field MR scanners significantly increases.


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Figure 2. The future of MRI from 2050 2059

2057 The ability to scan, analyse and

diagnose the body has taken a huge

leap forward by now. Hires, 3D

imaging of internal structures and brain activity is now possible using

realtime video, rather than static photos. This can be accomplished with

devices no bigger than a camera or tablet. By the late 2050s, MRI scans

have become as quick and easy as taking a photograph, with a

hundredfold decrease in cost.

Nikola Tesla discovered the Rotating Magnetic Field in 1882 in Budapest,

Hungary.

This was a fundamental discovery in physics.

In 1956, the "Tesla Unit" was proclaimed in the Rathaus of Munich,

Germany by the

International Electrotechnical CommissionCommittee of Action. All MRI

machines

are calibrated in "Tesla Units". The strength of a magnetic field is measured

in Tesla or Gauss Units. The stronger the magnetic field, the stronger the

amount of radio signals

which can be elicited from the body's atoms and therefore the higher the

quality of MRI

images.

1 Tesla = 10,000 Gauss


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LowField

MRI= Under .2 Tesla (2,000 Gauss)

MidField

MRI= .2 to 0.6 Tesla (2,000 Gauss to 6,000 Gauss)

HighField

MRI= 1.0 to 1.5 Tesla (10,000 Gauss to 15,000 Gauss)

In 1937, Columbia University Professor Isidor I. Rabi working in the Pupin

Physic Laboratory in Columbia University, New York City, observed the

quantum phenomenon dubbed nuclear magnetic resonance (NMR). He

recognized that the atomic nuclei show their presence by absorbing or

emitting radio waves when exposed to a sufficiently strong magnetic field.

NUMBER OF MRI MACHINES WOLRDWIDE


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III. Uses and Application of the Procedure

MR imaging of the body is performed to evaluate, diagnose or monitor

treatments for a variety of medical conditions, including: organs of the

chest and abdomenincluding the heart, liver, biliary tract, kidneys,

spleen, bowel, pancreas, and adrenal glands; pelvic organs including the

bladder and the reproductive organs such as the uterus and ovaries in

females and the prostate gland in males; blood vessels (including MR

Angiography); lymph nodes; Abnormalities of the brain and spinal cord;

Tumors, cysts, and other abnormalities in various parts of the body;

Injuries or abnormalities of the joints; Suspected uterine abnormalities in

women undergoing evaluation for infertility

Physicians use an MR examination to help diagnose or monitor treatment

for conditions such as: tumors of the chest, abdomen or pelvis; diseases of

the liver, such as cirrhosis, and abnormalities of the bile ducts and

pancreas; inflammatory bowel disease such as Crohns disease and

ulcerative colitis; heart problems, such as congenital heart disease;

malformations of the blood vessels and inflammation of the vessels

(vasculitis); a fetus in the womb of a pregnant woman.


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An MRI scan can be used as an extremely accurate method of disease

detection throughout the body and is most often used after the other

testing fails to provide sufficient information to confirm a patient's

diagnosis. In the head, trauma to the brain can be seen as bleeding or

swelling. Other abnormalities often found include brain aneurysms,stroke,

tumors of the brain, as well as tumors or inflammation of the spine.

Neurosurgeons use an MRI scan not only in defining brain anatomy but in

evaluating the integrity of the spinal cord after trauma. It is also used when

considering problems associated with the vertebrae or intervertebral discs

of the spine. An MRI scan can evaluate the structure of the heart and

aorta, where it can detect aneurysms or tears. MRI scans are not the first

line of imaging test for these issues or in cases of trauma.

It provides valuable information on glands and organs within the abdomen,

and accurate information about the structure of the joints, soft tissues,

and bones of the body. Often, surgery can be deferred or more accurately

directed after knowing the results of an MRI scan.

IV.Procedure

A.Preparation

The presence of a strong magnetic field means the metal objects of any kind

are not permitted within the scanning room during an MRI Scan. All

jewellery and clothing containing metal, particularly objects containing iron

need to be removed. Internal metal objects such as metal clips, medication
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pumps, or any internal metal items such as shrapnel or metal particles

also present a considerable risk and must be made known to the doctor.

Other equipment that may cause a risk include cardiac pacemakers or

defibrillators; a catheter with metal components; aneurysm clips and

cochlear implants. Some metal implants do not rule out using an MRI

scanner, but some do and it is important to tell a doctor about any

implants or metallic objects. If the patient suspects they may bepregnant,

the doctor must be informed as little is known about the effect of MRI

scans on an unborn baby. To improve the experience of the MRI, it is

advised that the patient not drink for several hours before the scan. This is

especially true of coffee and tea, as going to the toilet is not possible

without interrupting the scan and beginning again.

B.How does it Work?

An MRI scanner is a cylindrical machine, used to get images of the human

body. An MRI machine consists of a round tunnel within where the patientlies on a narrow table. An image of this is seen to the right. Surrounding

the tube is a large cylindrical magnet. During an MRI Scan, the patient is

within a stable magnetic field which is 10,000 30,000 times stronger than

the earths magnetic field. Protons are tiny particles that are present in

water molecules throughout the body. These are aligned by the incredibly

strong magnetic field, noting that there are no water molecules in the

human skeleton, only in bodily tissue. Radio waves are transmitted in

pulses, and these protons produce echoes that are emitted out of the body.

These echoes are received by theMRIscanner, and are then reconstructed
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into images of the body by a computer. These images are very precise and

give a clear anatomical view of the body from any angle.

C.How does MRI performed?

Once you are dressed in a medical gown, you will then be asked to lie down

on a narrow table which then moves into the tunnel. An MRI can last from

30 minutes to an hour, depending on the scans being performed. The scan

consists of sequences, lasting from 2-15 minutes, during which the

machine makes knocking noises, which can be loud. Patients are often

provided with earphones to listen to music to distract them from these

noises during the procedure. It is essential that the patient must remain

motionless in order to produce a clear picture. For some patients

claustrophobia may be an issue as the space within the MRI can be

confining. Subsequently those with claustrophobicanxietyand childrenmay need light sedation. Throughout the procedure imaging technicians are

able to communicate with the patient via intercom to ensure that the

patient is informed and comfortable.

After the MRI scan a radiologist, who is a physician experienced in MRI and

other radiology examinations, will analyze the images and send a report

with his or her interpretation to the patients personal physician. Thepatient receives MRI results from the referring physician who ordered the

test. The image is available almost immediately, but the time from when the

image is made available to when a report is issued will vary depending on

the complexity of the case.
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D.What will you experience after the procedure?

Most MRI exams are painless. However, some patients find it uncomfortableto remain still during MR imaging. Others experience a sense of being

closed-in (claustrophobia). Therefore, sedation can be arranged for those

patients who anticipate anxiety, but fewer than one in 20 require

medication.

It is normal for the area of your body being imaged to feel slightly warm,

but if it bothers you, notify the radiologist or technologist. It is important

that you remain perfectly still while the images are being obtained, which is

typically only a few seconds to a few minutes at a time. You will know when

images are being recorded because you will hear and feel loud tapping or

thumping sounds when the coils that generate the radiofrequency pulses

are activated. Some centers provide earplugs, while others use headphones

to reduce the intensity of the sounds made by the MRI machine. You will be

able to relax between imaging sequences, but will be asked to maintainyour position without movement as much as possible.

In some cases, intravenous injection of contrast material may be

performed. The intravenous needle may cause you some discomfort when it

is inserted and you may experience some bruising. There is also a very

small chance of irritation of your skin at the site of the IV tube insertion.

Some patients may sense a temporary metallic taste in their mouth after

the contrast injection.

V. Benefits and Risk


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A.Benefits

MRI is a noninvasive imaging technique that does not involve exposure to

ionizing radiation. MR images of the soft-tissue structures of the body

such as the heart, liver and many other organs is more likely in some

instances to identify and accurately characterize diseases than other

imaging methods. This detail makes MRI an invaluable tool in early

diagnosis and evaluation of many focal lesions and tumors. MRI has proven

valuable in diagnosing a broad range of conditions, including cancer, heart

and vascular disease, and muscular and bone abnormalities. MRI enables

the discovery of abnormalities that might be obscured by bone with other

imaging methods. MRI allows physicians to assess the biliary system

noninvasively and without contrast injection. The contrast material used in

MRI exams is less likely to produce an allergic reaction than the iodine-

based contrast materials used for conventional x-rays and CT scanning.

MRI provides a noninvasive alternative to x-ray, angiography and CT for

diagnosing problems of the heart and blood vessels.

B.Risk and Disadvantages

The MRI examination poses almost no risk to the average patient when

appropriate safety guidelines are followed. If sedation is used, there are

risks of excessive sedation. The technologist or nurse monitors your vital

signs to minimize this risk. Although the strong magnetic field is not

harmful in itself, implanted medical devices that contain metal may


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malfunction or cause problems during an MRI exam. There is a very slight

risk of an allergic reaction if contrast material is injected. Such reactions

usually are mild and easily controlled by medication. If you experience

allergic symptoms, a radiologist or other physician will be available for

immediate assistance. Nephrogenic systemic fibrosis is currently a

recognized, but rare, complication of MRI believed to be caused by the

injection of high doses of gadolinium-based contrast material in patients

with very poor kidney function. Careful assessment of kidney function

before considering a contrast injection minimizes the risk of this very rare

complication.

Manufacturers of intravenous contrast indicate mothers should not

breastfeed their babies for 24-48 hours after contrast medium is given.

However, both the American College of Radiology (ACR) and the European

Society of Urogenital Radiology note that the available data suggest that it

is safe to continue breastfeeding after receiving intravenous contrast.

Figure 1 Accidents Happen becauseof strong magnetic Field


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The magnet may cause pacemakers, artificial limbs, and other implanted

medical devices that contain metal to malfunction or heat up during the

exam. Any loose metal object may cause damage or injury if it gets pulled

toward the magnet. If a contrast agent is used, there is a slight risk of an

allergic reaction. MRI contrast agents can cause problems in patients with

significant kidney disease. Dyes from tattoos or tattooed eyeliner can cause

skin or eye irritation. Medication patches can cause a skin burn. The wire

leads used to monitor an electrocardiogram (ECG) trace or respiration

during a scan must be placed carefully to avoid causing a skin burn.

Prolonged exposure to radio waves during the scan could lead to slight

warming of the body.

Here is a news about an accident happens in MRI session.

Aug. 1, 2001 -- Despite the horrific MRI accident that caused the death of

6-year-old Michael Colombini earlier this week in Valhalla, N.Y., many

medical experts reiterate that the use of the imaging test is safe when used

appropriately. Colombini was undergoing an MRI, or magnetic resonance

imaging, at Westchester County Medical Center last Friday when an oxygen

canister was turned into a guided missile by the powerful MRI magnet. The

canister was drawn into the magnet core while the boy was in the machine.

The result was a fatal blow to the child's head. He died on Sunday. Frank

Shellock, MD, an MRI safety expert who has been tracking MRI-related

accidents for 16 years tells WebMD that this is the first death caused by an

MRI projectile, and that any kind of MRI accident is "relatively rare." MRIs

have been used regularly by doctors since "1982, and it is estimated that

about 10 million MRI imaging studies are done in the United States each


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year," says Shellock, who is a clinical professor of radiology at the

University of Southern California. 2001 WebMD, Inc. All rights reserved.

VI.Limitation

High-quality images are assured only if you are able to remain perfectly still

and follow breath-holding instructions while the images are being recorded.

If you are anxious, confused or in severe pain, you may find it difficult to lie

still during imaging.

The presence of an implant or other metallic object sometimes makes it

difficult to obtain clear images. Patient movement can have the same effect.A very irregular heartbeat may affect the quality of images obtained using

techniques that time the imaging based on the electrical activity of the

heart, such as electrocardiography (EKG).

An MRI is a very expensive and time consuming investigation compared to

other methods such asx-rayandCT. Some parts of the body, like bone, are

better examined using simpler techniques such as an X-Ray. An MRI may

not always be able to tell the difference between some disease processes. It

is also not a very good investigation for emergencies or accidents because of

the long time it takes and the fact that all equipment has to be removed

from the room while the machine is running.
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VII. The equipment

A.Appearance and Process

The traditional MRI unit is a large cylinder-shaped tube surrounded by a

circular magnet. You will lie on a moveable examination table that slides

into the center of the magnet.

Some MRI units, calledshort-bore systems, are designed so that the

magnet does not completely surround you. Some newer MRI machines have

a larger diameter bore which can be more comfortable for larger size

patients or patients with claustrophobia. Other MRI machines are open on

the sides (open MRI). Open units are especially helpful for examining larger

patients or those with claustrophobia. Newer open MRI units provide very

high quality images for many types of exams; however, older open MRI

units may not provide this same image quality. Certain types of exams

cannot be performed using open MRI. For more information, consult your

radiologist.

The computer workstation that processes the imaging information is

located in a separate room from the scanner.
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Figure 1: Picture of MRI Equipment Figure 2: Siemens Allegra 3T

Figure 3: A schematic representation

of the major systems on a

magnetic resonance imager.

B.Comparison to other Imaging Equipment

Unlike conventional x-ray examinations and computed tomography (CT)scans, MRI does not depend on ionizing radiation. Instead, while in the

magnet, radio waves redirect alignment of hydrogen atoms that naturally

exist within the body without causing any chemical changes in the tissues.

As the hydrogen atoms return to their usual alignment, they emit energy


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that varies according to the type of body tissue in which they lie. The MR

scanner listens for this energy and creates a picture of the tissues scanned.

The magnetic field is produced by passing an electric current through wire

coils in most MRI units. Other coils, located in the machine and in some

cases, placed around the part of the body being imaged, send and receive

radio waves, producing signals that are detected by the coils.

A computer then processes the signals and generates a series of images,

each of which shows a thin slice of the body. The images can then be

studied from different angles by the interpreting radiologist. The

differentiation of abnormal (diseased) tissue from normal tissues is better

with MRI than with other imaging modalities such as x-ray, CT and

ultrasound.

VIII.Types of MRI

A.Magnetic Resonance Angiogram(MRA)

An MRA, or magnetic resonance angiogram, is a type ofMRI scanthat uses

MRI's magnetic fields and radio waves to produce pictures of blood vessels

inside the body, allowing doctors to locate problems that may cause

reduced blood flow. An MRI, or magnetic resonance imaging, is the

technology behind an MRA, and it is used to examine soft ligament tissues

and tendon injuries. Both scans are generally safe for most patients and do

not expose them toionizing radiation.

B. Functional MRI
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This type of MRI is done on the brain, and not only shows the structure of

the brain, but also how much activity is taking place in each part. This has

been used to find out what parts of the brain are most active during certain

situations or tasks.Cardiac MRI: This can be used for several different

conditions and is dealt with separately.

Types of MRI Exams

Brain MRI

An MRI of the brain produces very detailed pictures of the brain. It is

commonly used

to study patients with headaches, seizures, weakness, blurry vision, etc. It

also can

further evaluate an abnormality seen on a CT scan. During the brain MRI,

a special

device called a head coil is placed around the patient's head. It does not

touch the

patient, and the patient can see through large gaps in the coil. This device

is what

helps to produce the very detailed pictures of the brain.

Cardiac MRI

Cardiac MRI can evaluate the size and thickness of the chambers of the

heart, the extent of damage caused by a heart attack or progressive heart

disease, and buildup of plaque and blockages in the blood vessels. It is an

invaluable tool for detecting and evaluating coronary artery disease and the

function of the heart muscles, valves and vessels.
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Spine MRI

This test is most commonly used to look for a herniated disc or narrowing

of the spinal canal (spinal stenosis) in patients with neck, arm, back

and/or leg pain. It is also the best test to look for a recurrent disc

herniation in a patient who has had prior back surgery.

Bone and Joint MRI

MRI can evaluate virtually all of the bones and joints, as well as the soft

tissues. Tendon, ligament, muscle, cartilage and bone injuries can be

diagnosed using MRI scans. It can also be used to look for infections and

masses.

Abdomen MRI

MRI of the abdomen is most frequently used to further evaluate an

abnormality seen on another test, such as an ultrasound or CT scan. Thus,

the exam is usually tailored to look at specific organs or tissues, such as

the liver, adrenal glands or pancreas.

Pelvic MRI

For women, pelvic MRI is used to evaluate the ovaries and uterus as

followup to an ultrasound exam which showed an abnormality. It is also

used to evaluate endometrial cancer. For men, pelvic MRI is sometimes

used to evaluate prostate cancer.


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Magnetic Resonance Imaging (MRI) Magnetic Resonance Andiography(MRA)


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IX. Microscopic Property Responsible for MRI

A.Basic Concepts and Basic Anatomy of an MRI System

The Static Magnetic Field

Magnetic resonance imaging requires a very strong magnetic field that has

precisely the same magnitude and direction everywhere in the region we

want to image. Uniformity or homogeneity is one of key properties to

describe MRI system quality. The strength of the magnetic field can be

difficult to understand because we rarely encounter strong magnetic field in


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everyday life. We use unit of gauss (G) or tesla (T), where 10000 gauss is

equal to 1 tesla, to describe the strength of the field.

The basic concept used both for creating the magnetic fields we need for

MRI and detecting the MR signal is that if we run an electrical current

through a wire, then a magnetic field is created around the wire. For the

design of MRI systems, this idea is extended further by wrapping wires in

repeated loops along the surface of a cylinder, which makes the magnetic

field stronger and more uniform over a larger volume at the center of the

cylindrical coil of wire.

Magnetic Field Gradient

A gradient in the magnetic field is what will allow us to accomplish this. A

magnetic field gradient is a variation in the magnetic field with respect to

position. A one-dimensional magnetic field gradient is a variation with

respect to one direction, while a two-dimensional gradient is a variation

with respect to two. The most useful type of gradient in magnetic resonance

imaging is a one- dimensional linear magnetic field gradient. A one-

dimensional magnetic field gradient along the x axis in a magnetic field, Bo,

indicates that the magnetic field is increasing in the x direction. Here the

length of the vectors represents the magnitude of the magnetic field. The

symbols for a magnetic field gradient in the x, y, and z directions are Gx, Gy,

and Gz.

Representing Images with Numbers and Vice-Versa

Digital Imaging and Communications in Medicine


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Digital Imaging and Communications in Medicine (DICOM) is a standard for

handling, storing, printing, andtransmittinginformation inmedical

imaging. It includes afile formatdefinition and a networkcommunications

protocol. The communication protocol is an application protocol that

usesTCP/IPto communicate between systems. DICOM files can be

exchanged between two entities that are capable of receiving image and

patient data in DICOM format.

A DICOM data object consists of a number of attributes, including items

such as name, ID, etc., and also one special attribute containing the image

pixel data (i.e. logically, the main object has no "header" as such: merely a

list of attributes, including the pixel data). A single DICOM object can have

only one attribute containing pixel data. For many modalities, this

corresponds to a single image. But note that the attribute may contain

multiple "frames", allowing storage of cine loops or other multi-frame data.

X. Bibliography and References
https://en.wikipedia.org/wiki/Data_transmissionhttps://en.wikipedia.org/wiki/Medical_imaginghttps://en.wikipedia.org/wiki/Medical_imaginghttps://en.wikipedia.org/wiki/File_formathttps://en.wikipedia.org/wiki/Communications_protocolhttps://en.wikipedia.org/wiki/Communications_protocolhttps://en.wikipedia.org/wiki/TCP/IPhttps://en.wikipedia.org/wiki/Data_transmissionhttps://en.wikipedia.org/wiki/Medical_imaginghttps://en.wikipedia.org/wiki/Medical_imaginghttps://en.wikipedia.org/wiki/File_formathttps://en.wikipedia.org/wiki/Communications_protocolhttps://en.wikipedia.org/wiki/Communications_protocolhttps://en.wikipedia.org/wiki/TCP/IP


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Magnetic Resonance Imaging (MRI) pages 1-8, Radiological Society of North

America, Inc.

Basic Principles of MRI, Simply Physics, simplyphysics.com

Magnetic Resonance Imaging: Historical Perspective,Journal of

Cardiovascular Magnetic Resonance(2006) 8, 573580 Copyright c_ 2006

Taylor & Francis Group, LLC

Basic Principles of MRI, James Voyvodic, Ph.D., Brain Imaging and

Analysis Center

Radiologyinfo.org, a resource produced by American College of Radiology

and Radiological Society of North America. Magnetic Resonance Imaging

-Body (MRI) Accessed 2/14/2014.

Food and Drug Administration, Radiation-Emitting Products: MRI

(Magnetic Resonance Imaging) Accessed 2/14/2014.

Copyright 1995-2014, The Cleveland Clinic Foundation.

Reimer P, Parizel PM, Stichnoth FA. Clinical MR Imaging: a Practical

Approach (2ndEdition). Heidelberg. Springer-Verlag. 2003.

Hornak, JP. The Basics of MRI. The Centre of Imaging Science. 2006.

July 1, 2015.http://www.cis.rit.edu/htbooks/mri/

Chernoff D, Stark P. Principles of Magnetic Resonance Imaging, UpToDate.

July 1, 2015.http://www.uptodate.com/contents/principles-of-magnetic-
http://www.cis.rit.edu/htbooks/mri/http://www.uptodate.com/contents/principles-of-magnetic-resonance-imaging?source=search_result&search=principles+of+magnetic+resonance+imaging&selectedTitle=1~150http://www.cis.rit.edu/htbooks/mri/http://www.uptodate.com/contents/principles-of-magnetic-resonance-imaging?source=search_result&search=principles+of+magnetic+resonance+imaging&selectedTitle=1~150


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resonance-imaging?

source=search_result&search=principles+of+magnetic+resonance+imaging

&selectedTitle=1~150

Magnetic Resonance Imaging: Body, Radiology Info. Radiological Society of

North America, 2006. July 1, 2015.http://www.radiologyinfo.org/

http://www.qmagnets.com/magnetic-field-gradients.php
http://www.uptodate.com/contents/principles-of-magnetic-resonance-imaging?source=search_result&search=principles+of+magnetic+resonance+imaging&selectedTitle=1~150http://www.uptodate.com/contents/principles-of-magnetic-resonance-imaging?source=search_result&search=principles+of+magnetic+resonance+imaging&selectedTitle=1~150http://www.uptodate.com/contents/principles-of-magnetic-resonance-imaging?source=search_result&search=principles+of+magnetic+resonance+imaging&selectedTitle=1~150http://www.radiologyinfo.org/http://www.qmagnets.com/magnetic-field-gradients.phphttp://www.uptodate.com/contents/principles-of-magnetic-resonance-imaging?source=search_result&search=principles+of+magnetic+resonance+imaging&selectedTitle=1~150http://www.uptodate.com/contents/principles-of-magnetic-resonance-imaging?source=search_result&search=principles+of+magnetic+resonance+imaging&selectedTitle=1~150http://www.radiologyinfo.org/http://www.qmagnets.com/magnetic-field-gradients.php

2.comprehensive written report (mri)

Documents