Magnetic resonance imaging, or MRI, is a way of obtaining very detailed images of organs and tissues throughout the body without the need for x-rays or "ionizing" radiation. Instead, MRI uses a powerful magnetic field, radio waves, rapidly changing magnetic fields, and a computer to create images that show whether or not there is an injury, disease process, or abnormal condition present. For the MRI procedure, the patient is placed inside of the MR scanner—typically a large, tunnel or doughnut-shaped device that is open at both ends. The powerful magnetic field aligns atomic particles called protons that are present in most of the body's tissues. The applied radio waves then cause these protons to produce signals that are picked up by a receiver within the MR scanner. The signals are specially characterized using the rapidly changing magnetic field, and, with the help of computer processing, very clear images of tissues are created as "slices" that can be viewed in any orientation. An MRI examination causes no pain, and the magnetic fields produce no known tissue damage of any kind. The MR scanner may make loud tapping, knocking or other noises at times during the procedure; using earplugs prevents problems that may be associated with this noise. You will be able to communicate with the MRI technologist or radiologist at any time using an intercom system or by other means.
MRI is the preferred procedure for diagnosing a large number of potential problems or abnormal conditions in many different parts of the body. In general, MRI creates pictures that can show differences between healthy and unhealthy tissues. Physicians use MRI to examine the brain, spine, joints (e.g., knee, shoulder, hip, wrist, and ankle), abdomen, pelvic region, breast, blood vessels, heart and other body parts.
The powerful magnetic field of the MR system will attract iron-containing (also known as ferromagnetic) objects and may cause them to move suddenly and with great force. This can pose a possible risk to the patient or anyone in an object's "flight path." Great care is taken to be certain that objects such as ferromagnetic screwdrivers and oxygen tanks are not brought into the MR system area. As a patient, it is vital that you remove all metallic belongings in advance of an MRI exam, including watches, jewelry, and items of clothing that have metallic threads or fasteners. Additionally, makeup, nail polish, or other cosmetics that contain metallic particles should be removed if applied to the area undergoing the MRI examination. The powerful magnetic field of the MR system will pull on any iron-containing object in the body, such as certain medication pumps or aneurysm clips. Every MRI facility has a comprehensive screening procedure and protocol that, when carefully followed, ensures that the MRI technologist and Radiologist knows about the presence of metallic implants and materials so that special precautions can be taken. In some unusual cases, due to the presence of an unacceptable implant or device, the exam may have to be canceled. For example, the MRI exam will not be performed if a ferromagnetic aneurysm clip is present because there is a risk of the clip moving or being dislodged. In some cases, certain medical implants can heat substantially during the MRI examination as a result of the radiofrequency energy that is used for the procedure. Therefore, it is very important to inform the MRI technologist about any implant or other internal objects that you may have. The magnetic field of the MR system may damage an external hearing aid or cause a heart pacemaker, electrical stimulator, or neurostimulator, to malfunction or cause patient injury. If you have a bullet or other metallic fragment in your body (e.g., any metallic foreign body) there is a potential risk that it could change position, possibly causing injury. In addition, a metallic implant or other objects may cause signal loss or distort the MR images. This may be unavoidable, but if the MRI Technologist and Radiologist know about it, allowances can be made when obtaining and interpreting the MR images.
What should patients expect?
Depending on the examination ordered, an MRI scan may take from 25 minutes up to an hour.
As a patient, it is vital that you remove all metallic belongings in advance of an MRI exam, including watches, jewelry, and items of clothing that have metallic threads or fasteners. Additionally, the MRI Technologist may ask that makeup, nail polish, or other cosmetics that contain metallic particles be removed if applied to the area undergoing the MRI examination.
If you are pregnant or suspect you are pregnant, you should inform the MRI technologist at time of scheduling your appointment and before the MRI examination is performed. In general, there is no known risk of using MRI in pregnant patients. However, Boulder MRI’s protocol is reserved for use in pregnant patients only to address very important problems or suspected abnormalities. In any case, MRI is safer for the fetus than imaging with x-rays or computed tomography (CT).
Some patients who undergo MRI examinations may feel confined, closed-in, or frightened. Perhaps one in twenty may require a sedative to remain calm. Boulder MRI’s machine configuration is much wider and shorter - for many patients, claustrophobia can be avoided by being examined in this newer MRI, more "open" design. Some MRI facilities permit a relative or friend to be present in the MR system room, which also has a calming effect. If patients are properly prepared and know what to expect, it is almost always possible to complete the examination.
While Boulder MRI caters to the comfort and health of our patients and clients, we do not prescribe medication or sedatives which may be helpful for your procedure. If needed, medication or sedatives must be ordered prior to your visit by a physician. We do not offer conscious sedation at Boulder MRI.
Will I be given a Contrast Agent?
Our MRI Technologists are certified to administers the contrast injection intravenously when necessary by request of the referring physician. Should the contrast agents by ordered for an arthrogram procedure, a Radiologist administers the contrast agents through a needle into the joint under fluoroscopic guidance.
Gadolinium is non-radioactive, colorless, and resembles clear water. This contrast agent does not contain iodine and allergic reactions are extremely rare. Contrast materials are safe drugs; adverse reactions ranging from mild to severe do occur, but severe reactions are very uncommon. While serious allergic or other reactions to contrast materials are rare, radiology departments are well-equipped to deal with them. Patients with a history of kidney diseases or liver damage should inform their physician before undergoing an MRI scan. Boulder MRI heavily prescreens for this history upon registration and immediately prior to performing the MRI examination.
The contrast agent, Gadolinium, does not contain iodine. However, if an arthrogram procedure is performed, an iodinated-based contrast material must be injected by the Radiologist under fluoroscopic guidance to ensure that the gadolinium is correctly placed into the joint capsule. A very small percentage of patients may develop a delayed reaction when an iodine-based contrast material is injected. Side effects can include a rash which can occur hours to days after an imaging exam. Most are mild, but severe rashes may require medication after discussion with your physician.
Contrast agents refer to the injection of a visual agent (Gadolinium) either intravenously (through a vein) or arthrography (injection into a joint) to increase contrast and visualization of tissues in certain anatomical structures. The use of artificial contrast media enhances the contrast between different parts of the body. Contrast media is used to help distinguish between parts of the body that have a similar composition to provide a clearer image of how the body is working, or if there is any disease present. With clearer images, the radiologist can provide your doctor with a more accurate diagnosis of your symptom or condition, to assist in deciding what treatment will be most appropriate. Contrast media are not needed for every type of imaging test in order to obtain very high- quality images. The radiologist will determine if the use of contrast will be helpful in your particular situation.