Wednesday, September 8, 2010

What is An MRI Scan?

MRI Scan

An MRI scan is a safe and painless test that can provide detailed pictures of organs and other structures inside your body.


What is an MRI scan?

MRI stands for magnetic resonance imaging. An MRI scan uses a strong magnetic field and radio waves to create pictures, on a computer, of tissues, organs and other structures inside your body.

How does an MRI scan work?

Your body contains millions of hydrogen atoms. When you are in an MRI scanner:
  • A strong magnetic field aligns particles called protons which are within the hydrogen atoms. All the protons line up in parallel to the magnetic field, like tiny magnets. (Normally the millions of protons all lie in random directions.)
  • Then, short bursts of radio waves are sent from the scanner into your body. The radio waves knock the protons from their position.
  • When the burst of radio waves stops, the protons realign back into place. As they do so they emit radio signals. The protons in different tissues of the body realign at different speeds. Therefore, the signal emitted from different body tissues varies. So, for example, softer tissues can be distinguished from harder tissues on the basis of the signals sent.
  • These signals are detected by a receiving device in the scanner.
  • The receiving device transmits the signals to a computer. The computer creates a picture based on the radio signals emitted from the body.

What does an MRI scan involve?

The MRI scanner is like a tunnel about 1.5 meters long surrounded by a large circular magnet. You lie on a couch which then slides into the scanner. A 'receiving device', like an aerial, is placed behind, or around, the part of the body being examined. This detects the tiny radio signals emitted from your body. When each 'picture' is being taken you need to keep still for a few minutes, otherwise the scan picture may be blurred.

The scan itself is painless. The whole procedure can take 15-40 minutes. It may be a little uncomfortable lying still on the couch for this time. Small children may need a general anaesthetic to keep them still long enough for the pictures to be taken. In some cases, an injection of a special contrast dye is given into the bloodstream via a vein on the arm. This helps to give clearer pictures of certain tissues or organs being examined.

The radiographer sits in the control room next to the scanner and observes through the window. However, you can talk to them, usually via an intercom, and you will be observed at all times on a monitor.

The scanner is noisy so you will be given some headphones or earplugs to protect your ears from the noise. Quite often you can listen to the radio through the headphones or bring a CD to listen to.

What is an MRI scan used for?

An MRI scan can create clear pictures of most parts of the body. So, it is useful for all sorts of reasons where other tests (such as X-rays) do not give enough information required. It is commonly used to get detailed pictures of the brain and spinal cord, to detect abnormalities and tumours. Even torn ligaments around joints can be detected by an MRI scan. So, it is being used more and more following sports injuries.

What preparation do I need to do before an MRI scan?

Usually very little. Your local hospital should give you information about what is required before you come for the scan. The MRI scanner uses an extremely strong magnet, so people with certain types of medical implant cannot be scanned. This is because the magnet can potentially move medical devices with metal in them, or affect their function.


Therefore, before you enter the scanning area you should be asked if you have any medical devices in your body. (You may have to fill in a safety questionnaire that asks about things that may contain metal.) The following is not a definitive list but may help remind you of the type of things radiographers need to know about:
  • Internal (implanted) defibrillator or pacemaker.
  • Cochlear (ear) implant.
  • Surgical clips such as those used on brain aneurysms.
  • Artificial heart valves.
  • Implanted drug infusion ports.
  • Implanted electronic device, including a cardiac pacemaker.
  • Artificial limbs or metallic joints.
  • Implanted nerve stimulators.
  • Pins, screws, plates, stents or surgical staples.
It is also important to tell the radiographer if you have ever had any metal fragments lodged in your eyes or your body. In some cases you may need an X-ray before an MRI scan to make sure you are safe to enter the scanner.

Are there any possible complications

MRI scans are painless and safe. Unlike X-rays and some other imaging tests, an MRI scan does not use radiation. However:
  • Rarely, some people have reactions to the contrast dye which is sometimes used.
  • Pregnant women are usually advised not to have an MRI scan unless it is urgent. Although the scan is thought to be safe, the long-term effects of strong magnetic fields on a developing baby are not yet known.

What can I expect after the scan?

There are no after-effects from the scan. You can return to your normal activities as soon as the scan is over. The pictures from the scan are studied by an X-ray doctor (a radiologist) who sends a report to the doctor who requested the scan.

Tuesday, September 7, 2010

MRI Scan Videos(Process brain scan)

MRI SCAN




MRI BRAIN SCAN


MRI Test | Cost


MRI Test Introduction



  • Invented in 1977, the Magnetic Resonance Imaging (MRI) scanning device changed medical history forever. MRI scanners are special pieces of medical equipment that give doctors the ability to see inside the entire body and split it up into sections. This gives medical professionals a 2D or 3D view of the body. This also allows the doctors a greater ability to diagnose patients faster and easier, helping to save millions of lives since its introduction to the medical community.








  • The Process



  • For an MRI scan to work, the patient is placed on a table that slides into the bore, or hole in the center of the machine. Once the part that needs to be scanned is in the isocenter of the machine's magnetic field, the scan begins. Once the scan has been completed, the information is sent from the MRI scanner to a computer screen where the data is compiled and displayed.              




  • What is an MRI?
    MRI stand for Magnetic Resonance Imaging which is a technology that uses magnetic signals to show the different tissues inside the body allowing a digital image of inside the human body to be created. MRI's are primarily used to study nerves, muscles, ligaments, bones, and numerous other tissues in the body, primarily soft tissues. There are approximately 26,000,000 MRI procedures performed each year making this one of the more common imaging technologies used to view inside the body.
    What does an average MRI cost?
    MRI cost can range between $400 to $3,500 depending upon which MRI procuedure is performed (example: brain MRI vs. shoulder MRI) and where you have the MRI test performed. The same exact MRI test can vary by hundreds of dollars from testing facility to testing facility. That's why it is important that you shop around to make sure you're getting the best possible price. By spending a little time and shopping around your local hospitals and imaging centers you can save hundreds if not thousands of dollars. MRI costs are broken down into two areas:
    Technical Fees: this is the cost of the procedure and where there is a potential to save a considerable amount of money.
    Professional Fees: this is the fee associated with having the radiologist interpret the test result. 

    Why do MRIs cost so much?

    MRI's are expensive because of the price of the equipment. With the average MRI machine costing over $1 million dollars they have to charge enough per test to cover the expense of the machine. Now, that doesn't mean you can get a better price that what is published. Similar to the price of a new automobile, everyone knows that the "sticker price" is just an asking price. There's a nice mark-up included in that price and often if you ask the dealer to come off that price they will. MRI procedures are often no different. Most hospitals and imaging centers have a "sticker price" which are often on the high end. If you ask and work with most facilities they will often offer a substantial discount to individuals and insurance carriers due to the form of payment and the volume of procedures they pay for on an annual basis.
    MRI Costs Averages
    As noted above, MRI costs can vary by hundreds and possibly thousands of dollars so it's important that you shop around to get the best price. For example, listed below are some real examples or MRI procedure prices from around the United States.
    Testing Facility Location Test Type Average Cost
    Orlando, FL MRI $2,229
    Dallas, TX - MRI Testing Facility A MRI $3,624
    Dallas, TX - MRI Testing Facility B MRI $2,172
    San Diego, CA MRI $2,826
    Salt Lake City, UT MRI $1,694
    Detroit, MI MRI $3,461






    Magnet


  • The most important part of an MRI machine is the magnet. MRI machines can utilize three different kinds of magnets, resistive, superconductive, and permanent. However, superconductive magnets are the most popular. The magnets in MRI scanners can use their magnetic fields to emit radio waves powerful enough to affect the body's atoms.




  • How it Works



  • Once the magnet has been turned on it creates a magnetic field. This powerful magnetic field is strong enough to move and manipulate the nuclei of the hydrogen atoms in our body. As the atoms return to their places, they emit radio waves. These waves can then be picked up by the MRI machine. The MRI machine can then determine the type of tissue in the body being scanned by the type of radio waves being sent out from the nuclei. The stronger the radio waves, the closer that atom is to the surface of the body. This allows the machine to also create a three-dimensional picture of the body based off of where the nuclei are in the body. The result is a full picture of the body displaying all of its tissues.




  • How it's Used



  • Since the MRI machine can determine what types of tissues are sending out the radio waves, it can also tell when the tissue is something like a tumor, a blood clot, or really any irregularity. This allows the doctors to make a diagnosis and begin further testing or treatment.










  • MRI Head Scan


    MRI Head Scan
    MRI (magnetic resonance imaging) is an imaging technique used to get cross-sectional images using strong magnetic field and radio waves (radio frequency pulses) instead of X-rays.  

        In MRI scanning, patients are placed inside a very large and strong magnet, so that all the protons in the atoms of the patient's body can be aligned to a magnetic field. Then, radio waves (called radio frequency pulses) are directed at the protons -- i.e., the nuclei of hydrogen atoms -- to excite the protons. Once the radio waves are stopped, excited atoms emit radio signals received by an antenna (i.e., a surface coil in the MRI machine), which are then measured and processed to form an image using a computer.  
     
       Head MRI provides detailed images of the brain, meninges, inner ear, and eye. MRI can distinguish brain gray matter from white matter, and find small tumors in the brain stem, inner ear, and eyes.

    Types of head MRI:
       1. Brain MRI
       2. Sellar MRI -- evaluates pituitary gland
       3. Head and Neck MRI
       4. Orbit MRI
       5. Temporal MRI -- evaluates the inner ear

    Advantages Of MRI Scan


  • Provides cross-sectional images in any anatomical plane (upper to lower, right to left, front to back, oblique).




  • Provides clear, detailed images of various soft tissues, such as gray and white matter of the brain, meninges, nerves, inner ear, eyes, blood vessels, temporomandibular joints, tumors, and fluids.




  • It is excellent in evaluating tumors of the brain, meninges, pituitary gland, and vascular or brain stem abnormality.




  • No radiation




  • Compared to the iodine-based contrast medium in X-ray or CAT scan, MRI dye is relatively safe. 





  •  Condition


  • To detect and evaluate tumors of the brain, head, and face




  • In cases involving stroke




  • Chronic neurological disorders such as multiple sclerosis




  • Dementia




  • Seizure




  • When vascular disease is suspected, in problems of the pituitary gland, and with inner ear abnormalities and complaints.   





  • MRI Brain and Head Neck   


  • Brain MRI



    1. Brain tumors -- including meningiomas, posterior fossa tumors, and acoustic neuromas
    2. Metastases, lymphoma
    3. Pituitary tumor or lesion
    4. Infections -- cerebritis, meningitis, brain abscess, toxoplasmosis
    5. Stroke -- cerebral infarction
    6. Vascular diseases -- cerebral aneurysms, arteriovenous malformations, sagittal sinus thrombosis
    7. Neurological disorders -- multiple sclerosis, multifocal leukoencephalopathy
    8. Intra-orbital or visual pathway lesions


  • Head-Neck MRI



    1. Head and neck cancer -- staging
    2. Disorders of the thyroid, parathyroid, and salivary glands; abnormalities of the throat, inner ear, and eyes.
    3. Temporomandibular joint dysfunction 
    Procedure

  • You will be asked to lie on the scan table. You will be asked to lie on the scan table. A head coil will be positioned around your head. After proper positioning, the exam table will slide into the center of the magnet.


  • During the scan you will be alone in the exam room, but you can talk to and listen to the technologist using an intercom, who will watch you through a glass window and video camera.




  • During actual scanning, you will hear loud tapping noises, but you are required to remain still until it's done (to get clear pictures).



  • In the event that a contrast medium is needed to make organs and blood vessels stand out, it will be injected into your vein during the exam.




  • The exam usually takes from 15 minutes to an hour and a half.




  • After proper positioning, the exam table will slide into the center of the magnet.




  • During the scan you will be alone in the exam room, but you can talk to and listen to the technologist using an intercom, who will watch you through a glass window and video camera.




  • During actual scanning, you will hear loud tapping noises, but you are required to remain still until it's done (to get clear pictures).




  • In the event that a contrast medium is needed to make organs and blood vessels stand out, it will be injected into your vein during the exam.




  • The exam usually takes from 15 minutes to an hour and a half.





  • MRI Scanner|MRI Scanning Machine

    MRI can help diagnose and monitor many different medical conditions. It's suitable for every part of the body, including the bones, soft tissues (such as blood vessels, ligaments and muscles) and the brain. MRI doesn't use X-rays.
    MRI doesn't cause pain or discomfort.

    A person having an MRI scan

    Diagnosis

    MRI is the best scan available for most conditions and can be used to investigate the entire body. It can be used for:
    • spinal, joint, ligament or tendon problems
    • measuring blood flow in blood vessels
    • diagnosing and planning of treatment for cancer
    • gynaecological problems
    • breast disease
    • assessment of brain function after a stroke
    • assessment of heart function

    Is MRI suitable for you?

    Not everyone can have an MRI scan. The magnetic field from the scan affects some metals. It's important to tell your radiographer (a health professional trained to perform MRI procedures) if you have a medical device implanted in your body. Examples include:
    • heart pacemaker
    • heart defibrillator (a device to establish a regular heart rhythm)
    • heart valve
    • medicine infusion pump (such as an insulin pump)
    • inner ear implant (a hearing aid)
    • neurostimulator (a device that stimulates nerves)
    • aneurysm clip (a metal clip on an artery)
    • shunts (tubes) in the brain
    • joint replacements/large metal implants
    • stents (tubes) in the heart or arteries
    • eye, penis, or breast implants
    • an intra-uterine contraceptive device or coil
    You will also need to tell your radiographer if you have:
    • shrapnel or gunshot wounds
    • body piercing
    • metal fragments anywhere in your body
    • tattoos or transdermal patches
    Not all of these mean that you won't be able to have an MRI scan. Your radiographer will discuss with you whether it's safe for you to go ahead with the scan.

    If you're pregnant

    MRI scans aren't usually done on pregnant women, but can be done after the first three months of pregnancy if absolutely necessary. If you think you are or could be pregnant, tell your radiographer before your MRI appointment.

    What are the alternatives?

    Depending on your circumstances, alternative procedures that can be used to make images of the inside of your body include X-ray, ultrasound or computerised tomography (CT) scan.
    Your doctor will advise you on the best examination for you if MRI is unsuitable.

    Preparing for your MRI scan

    Most MRI scans don't need any special preparation. However, if you're having an abdominal or pelvic scan, you may be asked to follow special instructions about eating and drinking.
    Some types of metal can interfere with the scan. Therefore, it's best to wear clothing that doesn't have metal zips, buttons, clasps or underwiring (such as bras).
    An MRI scan is usually performed as an out-patient procedure in a hospital. This means that you can have the scan and go home the same day.
    At the hospital, your radiographer will ask you to complete and sign a safety questionnaire.
    If you are anxious or have claustrophobia, you may be offered a sedative to help you relax during the scan. Young children may also be offered a sedative or a general anaesthetic. This means they will be drowsy/asleep during the procedure.
    Your radiographer may ask you to take off your clothes and put on a hospital gown.
    Your radiographer will ask you to remove metal objects such as hair clips, hearing aids, jewellery, glasses, dentures with metal components, your mobile phone and wrist watch. He or she will also ask you to leave behind coins, keys and your credit cards, and remove all make up.
    Relatives or friends who wish to accompany you into the MRI room also need to follow these guidelines, and complete and sign a safety questionnaire.

    Contrast medium (dye)

    A dye may be used to make some tissues show up more clearly. If needed, the dye is injected into a vein in your hand or arm. The dye is harmlessly removed from your blood by your kidneys and is passed out in your urine.
    A very small number of patients may be allergic to the dye. Tell your radiographer if you have any allergies. If you have poor kidney function you may need to have a test before having the dye injected.

    About the procedure

    The scan can take between 30 minutes and an hour and a half, depending on the specific examination.
    You will lie on your back on a movable table, which slides inside the cylinder shaped scanner. Generally the part of your body being examined is placed in the middle of the scanner. The scanner is open ended so you won't be completely enclosed at any time.
    Your radiographer will operate the scanner from behind a window, and will be able to see and hear you during the scan. You will be given an alarm call button to hold during the scan, which you can press to get your radiographer's attention.
    It can take several minutes for each image to be taken, and it's important to lie very still and breathe gently during the process. Your radiographer may ask you to hold your breath at certain times during the scan.
    The machine is noisy and will make loud knocking or buzzing sounds throughout the scan, so you will have to wear earplugs or headphones.
    When the scan is complete, the table will be removed from the scanner.

    What to expect afterwards

    You will usually be able to go home straight after the scan.
    Sedation temporarily affects your co-ordination and reasoning skills, so you mustn't drive, drink alcohol, operate machinery or sign legal documents for 24 hours afterwards. If you're in any doubt about driving always follow your doctor's advice, and please contact your motor insurer so that you're aware of their recommendations. This means if you had a sedative, you will need to arrange for someone to drive you home. You should try to have a friend or relative stay with you for the first 24 hours.
    If you have had a dye injection, it's a good idea to drink plenty of water for the next 24 hours to help flush the dye out of your body.
    Your radiologist (a doctor specialising in MRI, CT and X-ray methods to diagnose medical conditions) will examine your MRI scans and send the results to the doctor who requested your test.

    What are the risks?

    MRI scans are commonly performed and generally safe. However, in order to make an informed decision and give your consent, you need to be aware of the possible side-effects and the risk of complications of this procedure.

    Full Body MRI Scan|Whole body MRI Scan

    FULL BODY MRI SCAN
    Full body MRI is a complicated process but it can be done by expert with caring some tips.When Lauterbur and Damadian described the application of magnetic resonance imaging (MRI) as a clinical imaging tool in the early 1970s the popular belief was that the technique would become the ultimate screening tool for the whole body.1 2  However, similar to other modalities limited by cost, acquisition times, availability, and artefact produced by motion, it evolved as a technique to image stationary body parts. Supported by technical developments in the past decade, improved excitatory pulse sequences, and faster methods of localising derived signal, and by increasing awareness of the hazards of radiation imposed by traditional techniques, the ability to use MRI as a rapid imaging tool for the whole body has now been revisited.3–11  Reduced acquisition times have been mirrored by a logical reduction in acquisition costs, and the recent development of the moving MRI table top has facilitated the clinical introduction of this technique as a practical diagnostic tool.


    Oncological applications
    The principal application of whole body MRI is in detecting skeletal metastases as an alternative to skeletal scintigraphy.3–6 In contrast to scintigraphy, where localisation of tumour deposits is indirect and requires tumour induced activity in osteoblasts, the abundance of protons in the matrix of the tumour allows direct visualisation at MRI. Regional MRI has been shown to be more sensitive than skeletal scintigraphy in the detection of skeletal metastases. More recent studies comparing whole body MRI with scintigraphy have reproduced these results, and again MRI has been found to be at least as effective as scintigraphy (fig 1 and fig 2).3–5 Whole body MRI tends to better detect lesions in the spine and pelvis. In one study authors evaluating the use of whole body MRI as an alternative to bone scan reported finding metastases in 57 of 175 sites in 25 patients compared with 43 of 175 sites in the same 25 patients at scintigraphy (P < 0.001).4 In a more recent study whole body MRI showed 53 of 60 metastases identified at bone scintigraphy. Although lesions in the ribs and skull were missed at magnetic resonance imaging, additional bone metastases were identified when whole body MRI was used in the spine, pelvis, and femur.

    n addition to improving detection of skeletal metastases, whole body MRI may allow simultaneous evaluation of soft tissue organs and in so doing facilitate an overview of total tumour burden in an affected patient. In effect, rather than multimodality staging integrating skeletal scintigraphy with computed tomography of the chest, abdomen, and pelvis at the expense of radiation dose, a single whole body MRI scan may facilitate assessment of total tumour burden, particularly in patients whose tumours spread preferentially to brain, bone, and liver, such as breast and lung tumours. In this setting, tumour staging is done without exposing the patient to radiation. In a preliminary study of 17 patients with breast carcinoma, whole body MRI allowed detection of skeletal metastases in 11, liver metastases in five, and intracranial metastases in three patients. Interestingly, contrast enhanced computed tomography identified liver metastases in only three of the 17 patients.7

    Of the patients who present with skeletal metastatic disease 15% have no known primary tumour.8 In these patients, despite an extensive search integrating serological tests, endoscopy, and imaging, a primary tumour is likely to be found in only one in five patients at a mean cost of $16 000 (£7000; €12 000).8 As an alternative, total morphological assessment of the body, as afforded by whole body MRI, may allow the detection of a primary tumour as often as the other described, costly approaches. In a preliminary study using whole body MRI in this role, primary tumours were identified in the thyroid, prostate, and lung in patients presenting with skeletal metastases predominantly in the spine.8 Similar preliminary studies have proposed a role for positron emission tomography scanning in the same group of patients, to help localise the primary tumour.  

    Non-oncological applications
    A worldwide fall in autopsies has prompted a search for a minimally invasive alternative. Attempting to provide an acceptable alternative, whole body MRI has been shown to be effective in the gross assessment of the corpse, helping to identify sites suitable for percutaneous biopsy, particularly in immunocompromised hosts.9 Whole body MRI has been similarly successful in whole body fat measurements and body composition research, and more recently as a primary diagnostic tool in patients with polymyositis.10 11 The advent of molecular imaging, fusing the specificity of molecular technology with the spatial resolution of imaging, is likely to herald many new scanning applications for whole body sequences.
















    MRI Scan Spine

    WHAT IS MRI SCAN  OF SPINE ?

    MRI is a technique which have changed the dimensions of the medical science. It guides clear about the status of the fault in the parts of the body.Magnetic resonance imaging (MRI) is a noninvasive medical test that helps physicians diagnose and treat medical conditions.

    MR imaging 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 or CAT scanning).
    An MRI of the spine shows the anatomy of the vertebrae that make up the spine, as well as the disks, spinal cord and the spaces between the vertebrae through which nerves pass.
    Currently, MRI is the most sensitive imaging test of the spine in routine clinical practice.

    PROCEDURES
         * assess the spinal anatomy.
        * visualize anatomical variations and diseased tissue in the spine.
        * help plan surgeries on the spine such as decompression of a pinched nerve or spinal fusion.
        * monitor changes in the spine after an operation, such as scarring or infection.
        * guide the injection of steroids to relieve spinal pain.
        * assess the disks - bulging, degenerated or herniated intervertebral disk—a frequent cause of severe lower back pain and sciatica.
        * evaluate compressed (or pinched) and inflamed nerves.
        * explore possible causes in patients with back pain (compression fracture for example).
        * image spinal infection or tumors that arise in, or have spread to, the spine.

    PREPARATION FOR MRI SCAN OF SPINE
    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. For some types of exams, you will be asked to fast for 8-12 hours. Unless you are told otherwise, you may follow your regular daily routine and take medications as usual.

    Some MRI examinations may require the patient to swallow contrast material or receive an injection of contrast 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 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 1980's 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 from the MRI is assumed to outweigh the potential risks. See the Safety page (www.RadiologyInfo.org/en/safety/) for more information about pregnancy and MR imaging.

    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.

    Infants and young children usually require sedation to complete an MR exam without moving. Moderate and conscious sedation can be provided at most facilities. A physician or nurse specializing in the administration of sedation to children will be available during the exam to ensure your child's safety while under the effects of sedation. You will be given special instructions how to prepare your child for the sedation.

    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

    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.

    Parents who accompany children into the scanning room also need to remove metal objects and notify the technologist of any medical or electronic devices they may have.