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Pemeriksaan CT-Scan Kepala

A. Indikasi Pemeriksaan (Bontrager, 2001)

1. Tumor,massa dan lesi

2. Metastase otak

3. Perdarahan intra cranial

4. Aneurisma

5. Abses

6. Atrophy otak

7. Kelainan post trauma (epidural dan subdural hematom)

8. Kelainan congenital

B. Persiapan pemeriksaan

a. Persiapan pasien Tidak ada persiapan khusus bagi penderita, hanya saja instruksui-

instruksi yang menyangkut posisi penderita dan prosedur pemeriksaan harus diketahui

dengan jelas terutama jika pemeriksaan dengan menggunakan media kontras. Benda

aksesoris seperti gigi palsu, rambut palsu, anting-anting, penjempit rambut, dan alat bantu

pendengaran harus dilepas terlebih dahulu sebelum dilakukan pemeriksaan karena akan

menyebabkan artefak.Untuk kenyamanan pasien mengingat pemeriksaan dilakukan pada

ruangan ber-AC sebaiknya tubuh pasien diberi

selimut (Brooker, 1986)

b. Persiapan alat dan bahanAlat dan bahan yang digunakan untuk pemeriksaan kepala

dibedakan menjadi dua, yaitu :

1. Peralatan steril :

Alat-alat suntik

Spuit.

Kassa dan kapas

Alkohol

2. Peralatan non-steril

Pesawat CT-Scan

Media kontras

Tabung oksigen

c. Persiapan Media kontras dan obat-obatanDalam pemeriksaan CT-scan kepala pediatrik

di butuhkan media kontras nonionik karena untuk menekan reaksi terhadap media kontras

seperti pusing, mual dan muntah serta obat anastesi jika diperlukan. Media kontras digunakan

agar struktur-struktur anatomi tubuh seperti pembuluh darah dan orga-organ tubuh lainnya

dapat dibedakan dengan jelas. Selain itu dengan penggunaan media kontras maka dapat

menampakan adanya kelainan-kelainan dalam tubuh seperti adanya tumor.Teknik injeksi

secara Intra Vena ( Seeram, 2001 )

1. Jenis media kontras : omnipaque, visipaque

2. Volume pemakaian : 2 – 3 mm/kg, maksimal 150 m

3. Injeksi rate : 1 – 3 mm/sec

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C. Teknik Pemeriksaan

Posisi pasien : Pasien supine diatas meja pemeriksaan dengan posisi kepala dekat

dengan gantry.

Posisi Objek : Kepala hiperfleksi dan diletkkan pada head holder. Kepala diposisikan

sehingga mid sagital plane tubuh sejajar dengan lampu indikator longitudinal dan

interpupilary line sejajar dengan lampu indikator horizontal. Lengan pasien diletakkan

diatas perut atau disamping tubuh. Untuk mengurangi pergerakan dahi dan tubuh

pasien sebaiknya difikasasi dengan sabuk khusus pada head holder dan meja

pemeriksaan. Lutut diberi pengganjal untuk kenyamanan pasien ( Nesseth, 2000 ).

Scan Parameter

1. Scanogram : kepala lateral

2. Range : range I dari basis cranii sampai pars petrosum dan range II dari pars

petrosum sampai verteks.

3. Slice Thickness : 2-5 mm ( range I ) dan 5-10 mm ( range II )

4. FOV : 24 cm

5. Gantry tilt : sudut gantry tergantung besar kecilnya sudut yang terbentuk oleh

orbito meatal line dengan garis vertical.

6. kV : 120

7. mA : 250

8. Reconstruksion Algorithma : soft tissue

9. Window width : 0-90 HU ( otak supratentorial ); 110-160 HU ( otak pada

fossa posterior ); 2000-3000 HU ( tulang )

10. Window Level : 40-45 HU ( otak supratentorial ); 30-40 HU ( otak pada fossa

posterior ); 200-400 HU ( tulang )

Foto sebelum dan sesudah pemasukkan media kontras

o Secara umum pemeriksaan CT-scan kepala membutuhkan 6-10 irisan axial.

Namun ukuran tersebut dapat bervariasi tergantung keperluan diagnosa. Untuk

kasus seperti tumor maka jumlah irisan akan mencapai dua kalinya karena

harus dibuat foto sebelum dan sesudah pemasukan media kontras. Tujuan

dibuat foto sebelum dan sesudah pemasukan media kontras adalah agar dapat

membedakan dengan jelas apakah organ tersebut mengalami kelainan atau

tidak.

Gambar yang dihasilkan dalam pemeriksaan CT-scan kepala pada umumnya:

o Potongan Axial I

Merupakan bagian paling superior dari otak yang disebut hemisphere.

Kriteria gambarnya adalah tampak :

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a. Bagian anterior sinus superior sagital

b. Centrum semi ovale (yang berisi materi cerebrum)

c. Fissura longitudinal (bagian dari falks cerebri)

d. Sulcus

e. Gyrus

f. Bagian posterior sinus superior sagital

o Potongan Axial IV

Merupakan irisan axial yang ke empat yang disebut tingkat medial

ventrikel. Criteria gambarnya tampak :

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a. Anterior corpus collosum

b. Anterior horn dari ventrikel lateral kiri

c. Nucleus caudate

d. Thalamus

e. Ventrikel tiga

f. Kelenjar pineal (agak sedikit mengalami kalsifikasi)

g. Posterior horn dari ventrikel lateral kiri

o Potongan Axial V

Menggambarkan jaringan otak dalam ventrikel medial tiga. Kriteria

gambar yang tampak :

a. Anterior corpus collosum

b. Anterior horn ventrikel lateral kiri

c. Ventrikel tiga

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d. Kelenjar pineal

e. Protuberantia occipital interna

o Potongan Axial VII

Irisan ke tujuh merupakan penggambaran jaringan dari bidang orbita.

Struktur dalam irisan ini sulit untuk ditampakkan dengan baik dalam

CT-scan. Modifikasi-modifikasi sudut posisi kepala dilakukan untuk

mendapatkan gambarannya adalah tampak :

a. Bola mata / occular bulb

b. Nervus optic kanan

c. Optic chiasma

d. Lobus temporal

e. Otak tengah

f. Cerebellum

g. Lobus oksipitalis

h. Air cell mastoid

i. Sinus ethmoid dan atau sinus sphenoid

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CT Scan

Apa yang dimaksud dengan CT Scanning Tubuh?

Apakah kegunaan umumnya?

Bagaimana persiapannya?

Apa saja peralatannya?

Bagaimana prosedur kerjanya?

Bagaimana scan CAT dilakukan?

Apa yang akan saya alami selama dan setelah pemeriksaan ini?

Siapa yang menafsirkan hasil dan bagaimana cara mendapatkannya?

Apa manfaat dan risikonya?

Apa keterbatasan CT Scanning Tubuh?

Apa yang dimaksud dengan CT Scanning Tubuh?

CT scan-kadang disebut juga CAT scan-adalah tes medis non- invasif yang membantu dokter untuk

mendiagnosa dan mengobati kondisi medis.

CT scan menggabungkan peralatan khusus x-ray dengan komputer canggih untuk menghasilkan

gambar atau beberapa gambar bagian dalam tubuh. Gambar-gambar penampang dari daerah yang

sedang dipelajari dapat diperiksa pada monitor komputer, dicetak atau ditransfer ke CD.

CT scan organ, tulang, jaringan lunak dan pembuluh darah memberikan kejelasan yang lebih besar

dan memberikan rincian lebih dari pemeriksaan x-ray biasa.

Dengan menggunakan peralatan khusus dan keahlian untuk membuat dan menafsirkan CT scan

tubuh, ahli radiologi dapat lebih mudah mendiagnosa masalah seperti kanker, penyakit jantung,

penyakit menular, apendisitis, trauma dan gangguan muskuloskeletal.

Apakah kegunaan umumnya?

Pencitraan CT adalah:

Salah satu alat terbaik dan tercepat untuk mempelajari dada, perut dan panggul karena

menyediakan gambarnya secara rinci, memperlihatkan potongan melintang dari semua

jenis jaringan.

Merupakan metode yang digunakan untuk mendiagnosis bermacam-macam kanker,

termasuk paru-paru, hati, ginjal dan kanker pankreas, karena gambar memungkinkan dokter

untuk mengkonfirmasi adanya tumor dan mengukur ukuran, lokasi yang tepat dan sejauh

mana keterlibatan tumor dengan organ terdekat lainnya.

Pemeriksaan yang memainkan peran penting dalam diagnosis, deteksi dan pengobatan

penyakit pembuluh darah yang dapat menyebabkan stroke, gagal ginjal bahkan kematian. CT

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scan umumnya digunakan untuk menilai emboli paru (bekuan darah dalam pembuluh paru-

paru) serta untuk aneurisma aorta perut (AAA).

Berguna dalam mendiagnosa dan mengobati masalah tulang belakang dan luka pada tangan,

kaki dan struktur tulang lainnya karena dengan jelas dapat menunjukkan tulang bahkan yang

sangat kecil serta jaringan sekitarnya seperti otot dan pembuluh darah.

In pediatric patients, CT is rarely used to diagnose tumors of the lung or pancreas as well as

abdominal aortic aneurysms. For children, CT imaging is more often used to evaluate:

lymphoma

neuroblastoma

kidney tumors

congenital malformations of the heart, kidneys and blood vessels

Physicians often use the CT examination to:

quickly identify injuries to the lungs, heart and vessels, liver, spleen, kidneys, bowel

or other internal organs in cases of trauma.

guide biopsies and other procedures such as abscess drainages and minimally invasive

tumor treatments.

plan for and assess the results of surgery, such as organ transplants or gastric bypass.

stage, plan and properly administer radiation treatments for tumors as well as monitor

response to chemotherapy.

measure bone mineral density for the detection of osteoporosis.

How should I prepare?

You should wear comfortable, loose-fitting clothing to your exam. You may be given a gown

to wear during the procedure.

Metal objects including jewelry, eyeglasses, dentures and hairpins may affect the CT images

and should be left at home or removed prior to your exam. You may also be asked to remove

hearing aids and removable dental work.

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You may be asked not to eat or drink anything for several hours beforehand, especially if a

contrast material will be used in your exam. You should inform your physician of all

medications you are taking and if you have any allergies. If you have a known allergy to

contrast material, or "dye," your doctor may prescribe medications to reduce the risk of an

allergic reaction.

Also inform your doctor of any recent illnesses or other medical conditions and whether you

have a history of heart disease, asthma, diabetes, kidney disease or thyroid problems. Any of

these conditions may increase the risk of an unusual adverse effect.

Women should always inform their physician and the CT technologist if there is any

possibility that they are pregnant. See the Safety page for more information about pregnancy

and x-rays.

What does the equipment look like?

The CT scanner is typically a large, box-like machine with a hole, or short tunnel, in the

center. You will lie on a narrow examination table that slides into and out of this tunnel.

Rotating around you, the x-ray tube and electronic x-ray detectors are located opposite each

other in a ring, called a gantry. The computer workstation that processes the imaging

information is located in a separate control room, where the technologist operates the scanner

and monitors your examination.

How does the procedure work?

CT scan showing the liver

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CT slice through mid abdomen

In many ways CT scanning works very much like other x-ray examinations. X-rays are a

form of radiation—like light or radio waves—that can be directed at the body. Different body

parts absorb the x-rays in varying degrees.

In a conventional x-ray exam, a small amount of radiation is aimed at and passes through the

body, recording an image on photographic film or a special image recording plate. Bones

appear white on the x-ray; soft tissue, such as organs like the heart or liver, shows up in

shades of gray and air appears black.

With CT scanning, numerous x-ray beams and a set of electronic x-ray detectors rotate

around you, measuring the amount of radiation being absorbed throughout your body. At the

same time, the examination table is moving through the scanner, so that the x-ray beam

follows a spiral path. A special computer program processes this large volume of data to

create two-dimensional cross-sectional images of your body, which are then displayed on a

monitor. This technique is called helical or spiral CT.

CT imaging is sometimes compared to looking into a loaf of bread by cutting the loaf into

thin slices. When the image slices are reassembled by computer software, the result is a very

detailed multidimensional view of the body's interior.

Refinements in detector technology allow new CT scanners to obtain multiple slices in a

single rotation. These scanners, called multislice CT or multidetector CT, allow thinner slices

to be obtained in a shorter period of time, resulting in more detail and additional view

capabilities.

Modern CT scanners are so fast that they can scan through large sections of the body in

just a few seconds, and even faster in small children. Such speed is beneficial for all patients

but especially children, the elderly and critically ill.

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For children, the CT scanner technique will be adjusted to their size and the area of

interest to reduce the radiation dose.

For some CT exams, a contrast material is used to enhance visibility in the area of the body

being studied.

How is the CAT scan performed?

The technologist begins by positioning you on the CT examination table, usually lying flat on

your back or less commonly, on your side or on your stomach. Straps and pillows may be

used to help you maintain the correct position and to hold still during the exam. Depending

on the part of the body being scanned, you may be asked to keep your hands over your head.

Many scanners are fast enough that children can be scanned without sedation. In special

cases, sedation may be needed for children who cannot hold still. Motion will degrade the

quality of the examination the same way that it affects photographs.

If contrast material is used, it will be swallowed, injected through an intravenous line (IV) or

administered by enema, depending on the type of examination.

Next, the table will move quickly through the scanner to determine the correct starting

position for the scans. Then, the table will move slowly through the machine as the actual CT

scanning is performed. Depending on the type of CT scan, the machine may make several

passes.

You may be asked to hold your breath during the scanning. Any motion, whether breathing or

body movements, can lead to artifacts on the images. This is similar to the blurring seen on a

photograph taken of a moving object.

When the examination is completed, you will be asked to wait until the technologist verifies

that the images are of high enough quality for accurate interpretation.

The CT examination is usually completed within 30 minutes. The portion requiring

intravenous contrast injection usually lasts only 10 to 30 seconds.

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What will I experience during and after the procedure?

CT scan: appendicitis

CT scan: normal appendix

CT exams are generally painless, fast and easy. With helical CT, the amount of time that the

patient needs to lie still is reduced.

Though the scanning itself causes no pain, there may be some discomfort from having to

remain still for several minutes. If you have a hard time staying still, are claustrophobic or

have chronic pain, you may find a CT exam to be stressful. The technologist or nurse, under

the direction of a physician, may offer you some medication to help you tolerate the CT

scanning procedure.

If an intravenous contrast material is used, you will feel a pin prick when the needle is

inserted into your vein. You may have a warm, flushed sensation during the injection of the

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contrast materials and a metallic taste in your mouth that lasts for a few minutes. Some

patients may experience a sensation like they have to urinate but this subsides quickly.

If the contrast material is swallowed, you may find the taste mildly unpleasant; however,

most patients can easily tolerate it. You can expect to experience a sense of abdominal

fullness and an increasing need to expel the liquid if your contrast material is given by

enema. In this case, be patient, as the mild discomfort will not last long.

When you enter the CT scanner, special light lines may be seen on your body and are used to

ensure that you are properly positioned. With modern CT scanners, you will hear only slight

buzzing, clicking and whirring sounds as the CT scanner revolves around you during the

imaging process.

You will be alone in the exam room during the CT scan, unless there are special

circumstances. However, the technologist will always be able to see, hear and speak with you

at all times.

With pediatric patients, a parent may be allowed in the room but will be required to wear a

lead apron to minimize radiation exposure.

After a CT exam, you can return to your normal activities. If you received contrast material,

you may be given special instructions.

Who interprets the results and how do I get them?

A physician, usually a radiologist with expertise in supervising and interpreting radiology

examinations, will analyze the images and send a signed report to your primary care

physician or the physician who referred you for the exam, who will discuss the results with

you.

Follow-up examinations are often necessary, and your doctor will explain the exact reason

why another exam is requested. Sometimes a follow-up exam is done because a suspicious or

questionable finding needs clarification with additional views or a special imaging technique.

A follow-up examination may be necessary so that any change in a known abnormality can

be detected over time. Follow-up examinations are sometimes the best way to see if treatment

is working or if an abnormality is stable over time.

What are the benefits vs. risks?

Benefits

CT scanning is painless, noninvasive and accurate.

A major advantage of CT is its ability to image bone, soft tissue and blood vessels all

at the same time.

Unlike conventional x-rays, CT scanning provides very detailed images of many types

of tissue as well as the lungs, bones, and blood vessels.

CT examinations are fast and simple; in emergency cases, they can reveal internal

injuries and bleeding quickly enough to help save lives.

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CT has been shown to be a cost-effective imaging tool for a wide range of clinical

problems.

CT is less sensitive to patient movement than MRI.

CT can be performed if you have an implanted medical device of any kind, unlike

MRI.

CT imaging provides real-time imaging, making it a good tool for guiding minimally

invasive procedures such as needle biopsies and needle aspirations of many areas of

the body, particularly the lungs, abdomen, pelvis and bones.

A diagnosis determined by CT scanning may eliminate the need for exploratory

surgery and surgical biopsy.

No radiation remains in a patient's body after a CT examination.

X-rays used in CT scans usually have no immediate side effects.

Risks

There is always a slight chance of cancer from excessive exposure to radiation.

However, the benefit of an accurate diagnosis far outweighs the risk.

The effective radiation dose for this procedure varies. See the Safety page for more

information about radiation dose.

Women should always inform their physician and x-ray or CT technologist if there is

any possibility that they are pregnant. See the Safety page for more information about

pregnancy and x-rays.

CT scanning is, in general, not recommended for pregnant women unless medically

necessary because of potential risk to the baby.

Nursing mothers should wait for 24 hours after contrast material injection before

resuming breast-feeding.

The risk of serious allergic reaction to contrast materials that contain iodine is

extremely rare, and radiology departments are well-equipped to deal with them.

Because children are more sensitive to radiation, they should have a CT exam only if

it is essential for making a diagnosis and should not have repeated CT exams unless

absolutely necessary. CT scans in children should always be done with low-dose

technique.

What are the limitations of CT Scanning of the Body?

Soft-tissue details in areas such as the brain, internal pelvic organs, and joints (such as knees

and shoulders) can often be better evaluated with magnetic resonance imaging (MRI). A CT

exam is not generally indicated for pregnant women.

A person who is very large may not fit into the opening of a conventional CT scanner or may

be over the weight limit—usually 450 pounds—for the moving table.

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MRI (Magnetic Resonance Imaging)

What is MRI of the Body?

MRI of the knee

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.

The images can then be examined on a computer monitor, transmitted electronically, printed

or copied to a CD. MRI does not use ionizing radiation (x-rays).

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

determine the presence of certain diseases that may not be assessed adequately with other

imaging methods such as x-ray, ultrasound or computed tomography (also called CT, MDCT

or CAT scanning).

What are some common uses of the procedure?

MR imaging of the body is performed to evaluate:

organs of the chest and abdomen—including the heart, liver, biliary tract, kidneys,

spleen, bowel, pancreas and adrenal glands.

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pelvic organs including the reproductive organs in the male (prostate and testicles)

and the female (uterus, cervix and ovaries).

blood vessels (MR Angiography).

breasts.

Physicians use the MR examination to help diagnose or monitor treatment for conditions such

as:

tumors of the chest, abdomen or pelvis.

certain types of heart problems.

blockages, enlargements or anatomical variants of blood vessels, including the aorta,

renal arteries, and arteries in the legs.

diseases of the liver, such as cirrhosis and tumors, and that of other abdominal organs,

including the bile ducts, gallbladder, and pancreatic ducts.

diseases of the small intestine, colon, rectum and anus.

cysts and solid tumors in the kidneys and other parts of the urinary tract.

tumors and other abnormalities of the reproductive organs (e.g., uterus, ovaries,

testicles, prostate).

causes of pelvic pain in women, such as fibroids, endometriosis and adenomyosis.

suspected uterine congenital abnormalities in women undergoing evaluation for

infertility.

breast cancer and implants.

fetal assessment in pregnant women.

How should I prepare for the procedure?

You may be asked to wear a gown during the exam or you may be allowed to wear your own

clothing if it is loose-fitting and has no metal fasteners.

Guidelines about eating and drinking before an MRI exam vary with the specific exam and

also with the facility. Unless you are told otherwise, you may follow your regular daily

routine and take food and medications as usual.

Some MRI examinations may require the patient to receive an injection of contrast material

into the bloodstream. The radiologist or technologist may ask if you have allergies of any

kind, such as allergy to iodine or x-ray contrast material, drugs, food, the environment, or

asthma. However, the contrast material most commonly used for an MRI exam, called

gadolinium, does not contain iodine and is less likely to cause side effects or an allergic

reaction.

The radiologist should also know if you have any serious health problems or if you have

recently had surgery. Some conditions, such as severe kidney disease may prevent you from

being given contrast material for an MRI. If there is a history of kidney disease, it may be

necessary to perform a blood test to determine whether the kidneys are functioning

adequately.

Women should always inform their physician or technologist if there is any possibility that

they are pregnant. MRI has been used for scanning patients since the 1980s with no reports of

any ill effects on pregnant women or their babies. However, because the baby will be in a

strong magnetic field, pregnant women should not have this exam unless the potential benefit

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from the MRI exam is assumed to outweigh the potential risks. Pregnant women should not

receive injections of contrast material. See the Safety page for more information about

pregnancy and MRI.

If you have claustrophobia (fear of enclosed spaces) or anxiety, you may want to ask your

physician for a prescription for a mild sedative prior to the scheduled examination.

Jewelry and other accessories should be left at home if possible, or removed prior to the MRI

scan. Because they can interfere with the magnetic field of the MRI unit, metal and electronic

objects are not allowed in the exam room. These items include:

jewelry, watches, credit cards and hearing aids, all of which can be damaged. pins, hairpins, metal zippers and similar metallic items, which can distort MRI images. removable dental work. pens, pocketknives and eyeglasses. body piercings.

In most cases, an MRI exam is safe for patients with metal implants, except for a few types.

People with the following implants cannot be scanned and should not enter the MRI scanning

area unless explicitly instructed to do so by a radiologist or technologist who is aware of the

presence of any of the following:

internal (implanted) defibrillator or pacemaker cochlear (ear) implant some types of clips used on brain aneurysms some types of metal coils placed within blood vessels

You should tell the technologist if you have medical or electronic devices in your body,

because they may interfere with the exam or potentially pose a risk, depending on their nature

and the strength of the MRI magnet. Examples include but are not limited to:

artificial heart valves implanted drug infusion ports implanted electronic device, including a cardiac pacemaker artificial limbs or metallic joint prostheses implanted nerve stimulators metal pins, screws, plates, stents or surgical staples

In general, metal objects used in orthopedic surgery pose no risk during MRI. However, a

recently placed artificial joint may require the use of another imaging procedure. If there is

any question of their presence, an x-ray may be taken to detect the presence of and identify

any metal objects.

Patients who might have metal objects in certain parts of their bodies may also require an x-

ray prior to an MRI. You should notify the technologist or radiologist of any shrapnel,

bullets, or other pieces of metal which may be present in your body due to accidents. Dyes

used in tattoos may contain iron and could heat up during MRI, but this is rarely a problem.

Tooth fillings and braces usually are not affected by the magnetic field but they may distort

images of the facial area or brain, so the radiologist should be aware of them.

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Infants and young children usually require sedation or anesthesia to complete an MRI

exam without moving. Whether a child requires sedation will depend on the child’s age and

the type of exam being performed. Moderate and conscious sedation can be provided at most

facilities. A physician or nurse specializing in the administration of sedation or anesthesia to

children will be available during the exam to ensure your child's safety. You will be given

special instructions how to prepare your child for the sedation or anesthesia.

What does the equipment look like?

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, called short-bore systems, are designed so that the magnet does not

completely surround you; others are open on the sides (open MRI). These units are especially

helpful for examining patients who are fearful of being in a closed space and for those who

are very obese. Newer open MRI units provide very high quality images for many types of

exams; however, open MRI units with older magnets 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.

How does the procedure work?

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 the axes

of spinning protons, which are the nuclei of hydrogen atoms, in a strong magnetic field.

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.

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Frequently, 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.

How is the procedure performed?

MRI examinations may be performed on outpatients or inpatients.

You will be positioned on the moveable examination table. Straps and bolsters may be used

to help you stay still and maintain the correct position during imaging.

Devices that contain coils capable of sending and receiving radio waves may be placed

around or adjacent to the area of the body being studied.

If a contrast material will be used in the MRI exam, a nurse or technologist will insert an

intravenous (IV) line into a vein in your hand or arm. A saline solution may be used. The

solution will drip through the IV to prevent blockage of the IV line until the contrast material

is injected.

You will be moved into the magnet of the MRI unit and the radiologist and technologist will

leave the room while the MRI examination is performed.

If a contrast material is used during the examination, it will be injected into the intravenous

line (IV) after an initial series of scans. Additional series of images will be taken during or

following the injection.

When the examination is completed, you may be asked to wait until the technologist or

radiologist checks the images in case additional images are needed.

Your intravenous line will be removed.

MRI exams generally include multiple runs (sequences), some of which may last several

minutes.

Depending on the type of exam and the equipment used, the entire exam is usually completed

in 15 to 45 minutes.

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What will I experience during and after the procedure?

Most MRI exams are painless. However, some patients find it uncomfortable to 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 it.

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 recorded, which is typically only a few seconds to a few minutes at a

time. For some types of exams, you may be asked to hold your breath. You will know when

images are being recorded because you will hear tapping or thumping sounds when the coils

that generate the radiofrequency pulses are activated. You will be able to relax between

imaging sequences, but will be asked to maintain your position without movement as much

as possible.

You will usually be alone in the exam room during the MRI procedure. However, the

technologist will be able to see, hear and speak with you at all times using a two-way

intercom. Many MRI centers allow a friend or parent to stay in the room as long as they are

also screened for safety in the magnetic environment.

You may be offered or you may request earplugs to reduce the noise of the MRI

scanner, which produces loud thumping and humming noises during imaging. Children will

be given appropriately sized earplugs or headphones during the exam. MRI scanners are air-

conditioned and well-lit. Some scanners have music to help you pass the time.

When the contrast material is injected, it is normal to feel coolness and a flushing sensation

for a minute or two. The intravenous needle may cause you some discomfort when it is

inserted and once it is removed, 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 metallic taste in their mouth after the contrast injection.

If you have not been sedated, no recovery period is necessary. You may resume your usual

activities and normal diet immediately after the exam. A few patients experience side effects

from the contrast material, including nausea and local pain. Very rarely, patients are allergic

to the contrast material and experience hives, itchy eyes or other reactions. If you experience

allergic symptoms, notify the technologist. A radiologist or other physician will be available

for immediate assistance.

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. The

ACR Manual on Contrast Media states:

"Review of the literature shows no evidence to suggest that oral ingestion by an infant of the

tiny amount of gadolinium contrast medium excreted into breast milk would cause toxic

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effects. We believe, therefore, that the available data suggest that it is safe for the mother and

infant to continue breastfeeding after receiving such an agent.

If the mother remains concerned about any potential ill effects, she should be given the

opportunity to make an informed decision as to whether to continue or temporarily abstain

from breastfeeding after receiving a gadolinium contrast medium. If the mother so desires,

she may abstain from breastfeeding for 24 hours with active expression and discarding of

breast milk from both breasts during that period. In anticipation of this, she may wish to use a

breast pump to obtain milk before the contrast study to feed the infant during the 24-hour

period following the examination."

For further information please consult the ACR Manual on Contrast Media and its

references.

Who interprets the results and how do I get them?

A radiologist, a physician specifically trained to supervise and interpret radiology

examinations, will analyze the images and send a signed report to your primary care or

referring physician, who will share the results with you.

Follow-up examinations are often necessary, and your doctor will explain the exact reason

why another exam is requested. Sometimes a follow-up exam is done because a suspicious or

questionable finding needs clarification with additional views or a special imaging technique.

A follow-up examination may be necessary so that any change in a known abnormality can

be detected over time. Follow-up examinations are sometimes the best way to see if treatment

is working or if an abnormality is stable over time.

What are the benefits vs. risks?

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.

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Risks

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 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 contrast

material in patients with very poor kidney function.

What are the limitations of MRI of the Body?

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

breath, if requested to do so, 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.

A person who is very large may not fit into the opening of a conventional MRI machine.

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

clear images. Patient movement can have the same effect.

Breathing may cause artifacts, or image distortions, during MRIs of the chest, abdomen and

pelvis. Bowel motion is another source of motion artifacts in abdomen and pelvic MRI

studies. This is less of a problem with state-of-the art scanners and techniques.

Although there is no reason to believe that magnetic resonance imaging harms the fetus,

pregnant women usually are advised not to have an MRI exam unless medically necessary.

MRI may not always distinguish between cancer tissue and edema fluid.

MRI typically costs more and may take more time to perform than other imaging modalities.