Rabu, 21 Disember 2011
Magnetic Resonance Imaging MRI
Magnetic Resonance Imaging
MRI or Magnetic Resonance Imaging is a technology that revolutionized several fields. This method of scanning was developed primarily for use in medicine, but it has also been used to study fossils and historical artifacts. Early doctors were only able to gather data about a patient through observation and rudimentary tests. X-rays provided doctors with one of the first ways of peering within a living person. The MRI was one of the exciting successors to the X-ray.
To perform a MRI scan, the patient is securely placed on an imaging table within a large MRI scanner. Powerful magnetic fields are administered to align the nuclei within the atoms of the patient's body. Next, radio frequency pulses are applied; finally, the nuclei release some of the radio frequency energy and these emissions are detected by the MRI equipment. With this data, a computer generates a surprisingly detailed view of tissues within the body.
Earlier imaging technologies, such as X-rays, were able to detect dense tissues, particularly bones. MRIs give doctors the ability to view all sorts of body structures including soft tissues.
MRIs are frequently used to detect cancers that would otherwise be difficult to diagnose, such as mesothelioma. The ability to detect abnormalities, such as cancers at their early stages, has brought these scanners to the forefront of the battle against many diseases. It is generally believed that patients are not harmed by undergoing the procedure, since MRIs do not use radiation. There are not any side effects, but patients with pacemakers or other metallic implants are not eligible for these scans.
Exams typically take between 30 minutes and one hour. Early models of MRI scanners required patients to be placed in confined positions; newer versions of these machines, however, are based on an open design that is much more spacious and comfortable. The images themselves are often available immediately after the scan and the patient is able to resume normal activity.
I work at an MRI center. There are many metal objects that can safely go into an MRI scanner. The issue is what kind of metal is it. If it is attracted to a magnet, it should not even go into the room, much less into the scanner. Items that are real gold or real silver are not attracted to magnets, therefore safe to be in the room. (Like your wedding ring.) Also, implants such as knee implants, hip implants, staples and many other surgically implanted items often can be safely entered into the magnetic field. Since the advent of MRI and it being used so much, most surgical implants are of titanium, and not a problem. NO implants are put into the machine without documentation that the implant has been tested(endlessly and carefully in thorough research) that it is safe in a particular strength machine. Another consideration is that there are different 'strengths' (called 'Tesla') of machines. And a 3T machine is exponentially stronger than a 1.5T (which is common).
Bottom line - don't try to figure it out yourself. If you have anything that you weren't born with in or around your body, tell the technologist performing your scan before going into the room!!! They are responsible for your being safe. They have endless books and studies they can reference to know if an item is safe to be in the scanner room or not. Consider all the kinds of implants people can have now; stents, portacaths, staples, pins and rods, joint replacements, plates, etc, etc. If you tell the tech everything in or around your body, trust me, they will not Let you enter the room unsafely.
That said, you may have something like a 'safe to go into the room' pin in your leg, but they can't do your scan. That's because while the pin in your leg is safe to be in the machine, if you're getting a scan of the same part of the body where the metal is, it will distort the imaging, making it undiagnostic. (unable to give you information about the injury or reason you were scanned.) The metal distorts the imaging/picture.
Your safety is in the hands of you and your technologist. You - to let them know about anything on you that you weren't born with; and them - to make sure they don't put anything unsafe into the machine. In the 19 years I've worked in MRI - the only errors were made by people not letting the techs know about something. Never an error of a tech putting something into the machine that should not be there.
MRI procedures aren't like surgery, so the staples can't be ripped out of you. Though I don't know, I'd predict that the doctors intentionally used staples that wouldn't cause problems in an MRI. As for the wedding ring, I'm guessing that since it's probably not made out of magnetic material, it won't have a huge effect on the results of the MRI either.
If I were you, I'd trust the MRI technician.
hello , my name is lori and i am scheduled for an mri on the 18 of this month and i know from having done this before that you are suppose to take off all jewlery and when i called the mri department and told them i can not take off my wedding ring and i asked then if i had to cut it off in order to have the test and she told me no it is ok i could leave it on.is that true or due i have it cut off? won't it mess up the machine? also i had gastric by-pass 1yr. ago and surgical staples are still in me and they will be there for life what about them? will the machine rip them out of me? please find out for me .it is very important that i find out right away. thank you very much. lori
MRI stands for magnetic resonance imaging; it basically uses powerful magnets and radio waves to create detailed images of the interior of your body. It can be done with or without contrast. Contrast is a type of dye that is injected intravenously either right before, or during the procedure. Certain abnormalities, such as tumors, will absorb the dye and show up very clearly on the MRI with contrast. Your doctor will determine whether you need an MRI with contrast or without, and may order both tests.
An MRI scan is different than a regular x-ray or a CT scan, which both use ionizing radiation to create images. MRI scans generally produce clearer images with much more detail than an x-ray or CT scan. Small tumors, which may be invisible on an x-ray or CT scan, may be detected by MRI. In the case of most cancers, the earlier treatment is begun, the better the outcome of treatment, so an early MRI scan of any suspicious area can literally mean the difference between life and death.
As good as a standard MRI image is, the image can be improved even further by adding contrast. Tumors and other abnormalities will absorb the contrast dye as it progresses through your blood vessels, and on the MRI scan this area will glow. This allows for the detection of even the smallest tumors, and it also gives your doctor a clearer idea about the location and size of a tumor and which organs or tissues are involved. In addition, contrast allows a doctor to observe functional abnormalities that are not visible on a regular scan, particularly problems with how well your blood is flowing through your vessels.
The contrast medium used in MRI, generally gadolinium, is different than the contrast dyes used in x-rays or CT scans. Adverse reactions to gadolinium are much rarer than iodine-based dyes. However, if you have abnormal kidney function, you may be at increased risk for nephrogenic systemic fibrosis caused by the MRI dye. This complication is extremely rare, but always be sure your doctor and radiology technician are aware of any medical problems or allergies you may have, before you are injected with any type of contrast dye. Most people tolerate MRI with contrast just fine, and the benefits of early tumor detection generally outweigh the minor risks associated with the dye.
An MRI with contrast is generally painless, but you may experience some discomfort with the IV or needle used to inject the dye. You will be placed on a table and positioned so that the scan will show the affected area most clearly. You may be slid inside a long narrow tube in a closed MRI, or you may have an open MRI, in which the scanning equipment is shaped like a large doughnut and only scans a certain portion of your body at a time. The imaging process itself may take 45 minutes up to two hours, and you may be offered headphones so you can listen to music during the scan. Once the scanning is complete, a radiologist will read and interpret the scan and your doctor will discuss the results with you.