What is MRI?
Mason General Hospital's Diagnostic Imaging Department has Magnetic Resonance Imaging (MRI) available. MRI technology combines a powerful magnet, radio waves, and a computer to produce high-quality images that assist physicians in assessing a patient’s condition. It differs from both the x-ray and CT scan because it uses radio waves to pass through the body. This provides exceptional pictures showing soft body tissue in great detail.
There are no known side effects and the unit uses no harmful radiation. Nearly any body part may be evaluated from nearly any angle.
New "Open" MRI
Our new, Panorama High Field Open MRI is now in service! The MRI is spacious and comfortable, boasting an almost 360-degree opening, so that anyone with claustrophobia can be scanned in comfort. No longer will patients have to use the mobile MRI that was located outside of the building, as this new, state-of-the-art MRI is now located inside the Hospital for convenience and privacy.
With your physician’s referral, call (360) 427-9590 to schedule your scan.
Radiology Chief Talks About Hospital's High-Tech CT and MRI
In the past 15 months MGH&FC has added two state-of-the-art diagnostic imaging scanners that no other health care facility in the South Sound region can come close to offering patients – a low dose, large bore, high resolution CT; and a large, open, high resolution MRI. MGH&FC’s Chief of Radiology, board-certified Radiologist Kevin Roscoe, M.D., and Michael Gray, Director of Diagnostic Imaging, were instrumental in bringing these two scanners to MGH.
Q - Dr. Roscoe, this is a very basic question for you – but what does “CT” mean?
A - CT is an acronym for Computed Tomography, often times referred to as a CAT (computer assisted tomography) scan.
Q - You stated that MGH&FC purchased this new CT scanner to “increase image quality while at the same time improving patient care, safety, and comfort”. Can you explain what this means to a patient?
A - First I would like to comment on the CT’s increased image quality, which is very exciting for me as a radiologist. The new Toshiba Prime 80 Slice CT scanner has better resolution than our previous 16-slice CT scanner, and is superior to the typical 64-slice scanners in the area. Its higher resolution allows us to see more detail in the scan to assure an accurate diagnostic study. This model scans the body at 0.5 mm increments, which means increased capability for scanning arteries of the head, neck and peripheral arteries.
To improve ‘safety’, the New CT scanner has the most up-to-date software package available in the new technology of iterative dose reduction. This means not only higher resolution, but lower radiation exposure. So far, this is typically less than 50 percent of the previous scanner, and sometimes as low as 10 percent. We are now starting to use the ultra-low dose chest CT scanning features for following lung nodules on patients who require repeated scans.
As for ‘comfort’, a patient can weigh up to 660 lbs. – and this is regardless of height. The CT scanner’s center opening is the largest in the area at 78 cm in diameter, compared to other models with openings of 70 cm. This allows not only for larger patients to fit more comfortably, but also for lateral table movement to optimize positioning of the patient and alleviate the feeling of claustrophobia during the scan.
Q - Experts say the images of this new CT are “finer than any other scanner in Western Washington”. Can you explain how that benefits the patient?
A - Besides the higher resolution of the 80-slice detector and its smaller increments of acquisition, the scanner also allows for very fast scan times – in the order of just a few seconds. This warrants less concern for a patient’s movements, i.e. breathing, etc. The patient also spends less time on the table, and a lower dose of contrast can be given for those scans that require contrast. The scans are processed incredibly fast and can be reformatted into three dimensional rotating images for the physician and surgeon. This occurs so instantaneously that occasionally an emergency room patient may have their images completed and interpreted before they are transferred to their room.
Q - What does MRI stand for?
A - MRI stands for Magnetic Resonance Imaging.
Q - The new MRI is called an “Open MRI”. Can you explain the benefits of this?
A - The “open” design allows a wide-open area to scan patients. The conventional MRI scanner is a long, horizontal tube that the patient slides into on the table, with the imaged part of the body positioned fully inside the tube. This can be disturbing for patients who have a tendency for claustrophobia – the fear of being in a confined space. The new, open MRI is a table with the cover above patient and all the sides open. The magnetic center is in the middle of the table, allowing the patient to be moved around and positioned at the center of the magnet, or the “sweet spot”. It can be directed over the specific area to be imaged, such as the knee or shoulder or brain. The open design is so open, in fact, that infants and children can be scanned in their mother’s arms. That way the mother can hold and comfort the child while in the scanner. Previous open MRIs had trouble with image quality due to their low magnetic field strength. The new open MRI has high field strength and open design, with images of the same quality as the tube models.
Q - Again, image quality is superb with this new MRI. How does a CT image differ from an MRI image?
A - Images from a CT and an MRI scan may look similar, but they are produced by very different methods. Basically, an MRI scans where water molecules are in the body, creating images from the signals produced by water interacting with a magnet. A CT produces images by scanning variations in the density of tissues and the absorption of x-rays from iodine in the contrast.
Q - A CT scanner uses radiation, whereas an MRI does not. Can you explain the difference between radiation vs. magnetism?
A - The CT scan uses x-rays – the same as those in a conventional chest or wrist x-ray, except the x-rays are emitted from a tube rotating very quickly around the body, with detectors on the end of the x-ray tube collecting data and reconstructing images in a three-dimensional display. This is a very fast imaging technology that can be done in a matter of seconds.
The MRI uses an incredibly strong magnet to excite tiny fractions of protons in the water molecules of the body, which then interact with a radio frequency, producing images from the data collected by very strong antennas. This is a rather slow process and therefore image acquisition may take 5 to 10 minutes per image, and an entire scan time of 30 minutes to an hour. Its very slow process makes it also susceptible to movement, and therefore the patient must remain as still as possible during the scan.
Q - When will a physician recommend a CT scan? MRI scan?
A - There are certain circumstances for both. Occasionally one may be substituted for the other, however, the decision is based on what type of data the physician needs. The CT scanner is very good at detecting blood in the brain and exquisitely sensitive for fractures, and therefore used heavily in the Emergency Room. It is also able to see the internal organs and bowel. The MRI is superior in imaging the soft tissues of the brain, spinal cord, and looking at ligaments and cartilage of the joints, such as the shoulder, knee, or hip. MRI also detects changes in the uterus and ovaries, and is often used by gynecologists.
Q - Are there concerns about having a child receive a CT and/or MRI? What should a parent look for when choosing a facility for an imaging study?
A - When imaging children, many factors need to be considered by the radiologist and the referring physician. The first priority is patient safety, and second is addressing the medical issue. Children and infants are more sensitive to the effects of radiation than older patients, and therefore prudent use of radiation is mandated by the ALARA principle, which stands for ‘as low as reasonably achievable’. The CT dose reduction makes this more achievable than before and can be lifesaving. The MRI cannot replace the CT in this regard, but it can be used effectively if the patient can hold still for the scan. On occasion, a patient may require sedation in order to remain still; and as mentioned earlier, a child can be held by a parent.
Preparing for your MRI
Your MRI requires very little effort on your part. It's a simple process, but preparation is essential! Here's what you need to know:
When Your Appointment Is Scheduled
Before we schedule you for an MRI exam, we will ask a number of questions. Your answers will help us identify any current conditions that may make it unsafe for your MRI. You will need to inform us if:
- you are pregnant
- you've ever had surgery
- you're on pain medication
- you're claustrophobic
- you have an incident of metal to your eyes
- you have cardiac valve replacements or a pacemaker, bone or joint replacements, or aneurysm clips, or cardiac stents
These conditions may not exclude you from having an MRI scan, but they'll be important determining factors. Please be prepared to provide information on your insurance and medical history. We'll be happy to discuss all aspects of your MRI exam and answer any remaining questions you may have at that time.
The Day Of Your MRI
Your first task for this day is simple: Relax. Typically you can eat normally and take prescribed medication the day of your MRI exam. If you are having an examination of the abdominal area your physician may request that you abstain from eating prior to your scan. For your personal comfort and enjoyment, you may like to have someone accompany you. He or she may be able to sit and talk with you during the exam. We recommend you wear comfortable clothing, free of snaps and zippers. Since rings, watches, and earrings are all metal, and thus, could interfere with your scan, please leave these items at home.
When You Arrive
Plan on arriving 30 minutes ahead of your scheduled appointment. Your technologist and/or patient care associate will discuss the procedure with you at that time.
Starting The Scan
To begin the examination, a technologist will help you lie down on a padded table. You will be positioned so that the part of your body to be examined lies in the center of the machine. A coil may be attached to the part of the body to be scanned, and your physician may request that a contrast agent be injected (to enhance the images). The table will then slide into the center of the MRI machine.
During The Scan
You will be asked to hold still for short periods of time while the scan is in progress. Expect to hear a loud knocking noise from the machine as the pictures are taken. The technologist who will be monitoring the exam from an adjoining room will be able to hear you and talk with you at all times.
After The Exam
When the scan is complete, your technologist will help you leave the table. In most cases, you may return to your normal activities immediately after the procedure.
With The Radiologist
A radiologist who is a specialist in MRI will then interpret your images. The radiologist will make an expert interpretation of the image and prepare a written report to be sent to your referring physician.
With Your Physician
Your personal doctor will review the findings of the MRI in the context of your overall condition and discuss them with you. Based on the interpretation and findings, you and your doctor will plan your treatment. Your doctor may choose to monitor your progress with another MRI scan.