What is an MRI?
Magnetic Resonance Imaging (MRI) is a diagnostic imaging technique that combines a powerful magnetic field with computer technology to produce exquisitely detailed images of your body's soft tissue (organs, muscles, fat). Because certain atoms in our cells respond, or resonate, slightly in the presence of magnetic fields, MRI is able to use that response to create an amazingly clear, detailed computer representation of internal organs, muscles, connective tissue, and the central nervous system. Using cross-sectional imaging of the body along multiple planes (like slices of bread), the clarity of these images is far greater than is available with conventional CT scans, X-rays, or even myelograms, allowing your physician to make an earlier and more accurate diagnosis. MRI is noninvasive (except in cases where contrast agents are injected), and doesn't expose patients to radioactive materials, X-ray, or any form of ionizing radiation. To the best of our knowledge, MRI produces no harmful side effects. What happens during an MRI scan?
Upon your arrival at Shields MRI, you will be welcomed by a friendly, knowledgeable, patient advocate who will obtain insurance information and answer any questions you may have. Please plan on arriving at least one half hour before your scheduled appointment time.
This is followed by a brief interview with an MRI technologist, who will discuss the procedure with you and confirm that you have no metal implants or other conditions that could interfere with the scan.
After discussing the exam with your technologist, you'll recline comfortably on a cushioned table and your exam will begin. Depending on what information your doctor needs, your MRI scan may require the use of an intravenously injected contrast, which will assist in visualizing certain structures in your body. If prescribed, this contrast will be administered by a specially trained Shields technologist. You will be in constant communication with your technologist throughout the entire exam.
As the MRI scanner calibrates to obtain each series of images, you will hear persistent buzzing and thumping noises, but at no time will you experience any physical sensation or discomfort. Click here to hear what an MRI sounds like. You may wear earplugs or listen to music during your exam if you wish.
While the pictures, or images, are being recorded, all you have to do is lie still and follow the technologist's simple instructions. The images obtained from your MRI are very sensitive to motion. Even the slightest movement can distort the image and limit its diagnostic value. As a result, it is important for you to remain as still as possible during your scan.
Most MRI exams last 20-40 minutes, although compound studies and Open MRI exams can last up to an hour. After your MRI, you may return home or to work. Shields MRI will contact your doctor over the next few days with the results of your study. Only your doctor is authorized to discuss your MRI results with you. How do I obtain results of the scan?
After you leave, your images are interpreted by a radiologist, a doctor who specializes in reading MRI. Within the next few days, the radiologist will contact your physician with the results of your study. Your physician will then contact you to discuss your results and, if necessary, prescribe treatment. Your physician is the only person authorized to discuss your MRI results with you.
Can anyone undergo an MRI exam?
Although an MRI is completely safe and painless, some people should not undergo an MRI, or will need to make special arrangements. Any of the following conditions may interfere with your MRI. Please call us immediately if you:
- Have a cardiac pacemaker
- Have a prosthetic heart valve
- Have a surgical clip, bone or joint replacement, or any metallic implant
- Have at any time held a job in a metal-working industry or one where you may have been exposed to metallic dust or splinters
- Have suffered a shrapnel wound
- Have any metallic chips or splinters in the eye
- Are pregnant, or think you might be
What does an MRI sound like?
Click here to hear what an MRI sounds like
Is there a checklist for the day of my visit?
Click here for a checklist What if I am claustrophobic?
Patients that are too claustrophobic to undergo an MRI scan do have options. Many of our claustrophobic patients obtain a prescription for a mild sedative from their physician and have a family member drive them to and from their exam. If you prefer, a friend, family member, or Shields MRI medical professional can sit in the room with you to provide support throughout your scan after he or she is screened for metal on or in the body. Open MRI systems are another terrific alternative for patients who are restricted by the size constraints of conventional MRI systems. Shields offers 7 Open MRI scanners throughout Massachusetts, available at our centers in Boston, Brockton, Cape Cod, Dartmouth, Springfield, Worcester, and Providence, RI. What is the difference between an Open MRI and a conventional, or high-field, MRI?
Open MRI is an outstanding tool for scanning patients who would otherwise not be able to benefit from MRI's invaluable diagnostic capabilities. Featuring a much larger patient gantry and an open-end design, Open MRI systems have become an attractive option for patients who have difficulty with the size constraints of conventional MRI systems, and provide a patient-friendly environment for high-quality routine head, neck, body, and musculoskeletal MRI exams.
Because an Open MRI machine is, in fact, open-ended, the magnetic field it produces is less than the magnetic field produced by a conventional, high-field scanner. Subsequently, Open MRI scan times can be considerably longer than those of high-field machines. For example, a shoulder scan on a standard high-field machine might take 20 minutes. On an Open MRI system, it could take close to an hour to produce similar results. Our modern high-field MRI scanners are capable of some amazing new studies that are not yet available on Open MRI systems. Therefore, certain types of exams can be performed only on high-field scanners. What is the difference between MRI and CT?
Both MRI and CT are diagnostic exams used to thoroughly image a selected area of the human body. Similarly, both MRI and CT require the use of a large machine, and each method relies upon computer technology to reconstruct a cross-sectional image of the body. Aside from these very fundamental similarities, there are many inherent differences between MRI and CT scans. • Magnetic Resonance Imaging (MRI)- Compared to CT, MRI technology is still in its infancy. Developed in the mid 1980's, MRI technology utilizes radio frequency waves and very powerful magnets. After applying a very strong, localized electromagnetic field, the MRI scanner emits a series of radio pulses into the body, exciting the hydrogen protons found in the body's soft tissue. Upon measuring the relaxation times of these hydrogen protons, the MRI scanner employs sophisticated computer technology to interpret the protons' behavior and recreates a 3-dimensional image of the body. Since hydrogen is the most abundant element in the body, MRI technology is capable of producing amazingly clear images of organs and soft tissue. MRI is able to detect disease or injury in muscle structure along ligaments, and is used to assist in the visualization of tumors. The ability to visualize soft-tissue and the vascular system make MRI an outstanding tool for imaging brain and spinal cord abnormalities. MRI is non-invasive, although certain studies may require the use of an intravenous contrast agent. MRI does not involve any ionizing radiation, and aside from a persistent thumping noise, patients will experience no discomfort or side effects. • Computerized Tomography (CT or CAT scan)- Developed in the 1970's CT technology utilizes a highly sensitive X-ray beam that is focused on a specific part of the body. Upon passing through the body, the beam hits a detector, which relays this information into a computer. The computer analyzes the information based upon tissue density, and feeds it into a cathode ray tube. Like MRI, a cross-sectional representation (like slices of bread) of the body is produced. Bone shows up white, gases and liquids black, and tissue as varying shades of gray, depending on density. Generally, CT provides much better visualization of bone detail than MRI. CT scans provide excellent information on anatomical features and tissue density (this allows for the detection of tumors, and sometimes the ability to distinguish between malignant and benign tumors). CT scans can also detect calcium deposits, cysts, and abscesses. They are often used in place of ultrasound for obese patients because fat deposits often hinder ultrasonic waves. CT scanning does carry with it the risks associated with X-ray exposure, although it is significantly less than that from ordinary X-rays. How long does an MRI exam take to complete?
Your entire visit to Shields will take anywhere from an hour to an hour and a half. You should arrive a half hour before your scheduled appointment time so our friendly medical staff can obtain your insurance information, explain the exam to you, and answer any of your questions. Depending on what information your doctor needs, the scanning process will last anywhere from 20 minutes to an hour, after which you may return home or to work. |
