Magnetic Resonance Imaging (MRI)

Magnetic Resonance Imaging (MRI) - Body

• What is MRI of the Body?
• What are some common uses for MRI of the Body?
• How is the MRI scan performed?
• Who interprets the results and how do I get them?
• What are the limitations of MRI of the Body?
• What are the benefits vs. risks?

What is MRI of the Body?

Magnetic resonance imaging (MRI) uses radiofrequency waves and a strong magnetic field rather than x-rays to provide remarkably clear and detailed pictures of internal organs and tissues. The technique has proven very valuable for the diagnosis of a broad range of pathologic conditions in all parts of the body including cancer, heart and vascular disease, stroke, and joint and musculoskeletal disorders. MRI requires specialized equipment and expertise and allows evaluation of somebody structures that may not be as visible with other imaging methods.

What are some common uses for MRI of the Body?

Organs of the chest and abdomen-including the lungs, liver, kidney, spleen, pancreas and abdominal vessels-are examined in high detail with MRI, enabling the diagnosis and evaluation of tumors and functional disorders. Because no radiation exposure is involved, MRI is often the preferred diagnostic tool for examination of the male and female reproductive systems, pelvis and hips and the bladder.

How is the MRI scan performed?

The patient is placed on a sliding table and positioned comfortably for the MRI examination. Then the technologist leaves the room and the individual MRI sequences are performed. The patient is able to communicate with the technologist at any time using an intercom. Also, many MRI centers allow a friend or, if a child is being examined, a parent to stay in the room. Depending on how many images are needed, the exam will generally take 45 minutes, although a very detailed study may take longer. You will be asked not to move during the actual imaging process, but between sequences some movement is allowed. Patients are generally required to remain still for only a few minutes at a time. Depending on the part of the body being examined, a contrast material (usually gadolinium) may be used to enhance the visibility of certain tissues or blood vessels. The contrast material is injected about two-thirds of the way through the exam. A small needle connected to an intravenous line is placed in an arm or hand vein for the injection. When the exam is over the patient is asked to wait until the images are examined to determine if more images are needed.

Who interprets the results and how do I get them?

A radiologist, who is a physician experienced in MRI and other radiology examinations, will analyze the images and send a signed report with his or her interpretation to the patient's personal physician. A preliminary interpretation may be available shortly after the exam and a formal report of the complete results will be sent to the referring physician within a day. Your primary physician or the radiologist may discuss the findings of the MRI examination with you. New technology also allows for distribution of diagnostic reports and referral images over the Internet to our facility.

What are the limitations of MRI of the Body?

Bone is better imaged by conventional x-rays in some cases and CT is preferred for patients with severebleeding. MRI may not always distinguish between tumor tissue and edema fluid and does not detect calcium when this is present within a tumor. In most cases the examination is safe for patients with metal implants, with the exception of a few types of implants, so patients should inform the technician of an implant prior to the test. The examination must be used cautiously in early pregnancy. MRI typically costs more than CT scanning.

What are the benefits vs. risks?

Benefits:

• Images of the soft-tissue structures of the body-such as the heart, lungs, liver and other organs-are clearer and more detailed than with other imaging methods.

• The detail makes MRI an invaluable tool in early diagnosis and evaluation of tumors.

• MRI contrast material is less likely to produce an allergic reaction than the iodine-based materials used for conventional x-rays and CT scanning.

• MRI enables the detection of abnormalities that might be obscured by bone with other imaging methods.

• MRI provides a fast, noninvasive alternative to x-ray angiography for diagnosing problems of the cardiovascular system. A variant called MR angiography (MRA) provides detailed images of blood vessels of the body-oftentimes without the need for contrast material. The risk of an allergic reaction from MRA contrast is extremely low and kidney damage does not occur.

• Exposure to radiation is avoided.

Risks:

• There are no definite side effects from any type of MRI study, including MR angiography.

• An undetected metal implant may be affected by the magnetic field. The procedure should be avoided in any patient with a pacemaker, implanted neurostimulator, certain types of metallic ear implants (cochlear implants) or metallic object within the eye socket. It should also be avoided if the patient has a port for delivering insulin or chemotherapy (however, many ports are detachable so patients can safely undergo MRI examinations).

• MRI is generally avoided in the first 12 weeks of pregnancy. Doctors usually use other methods of imaging, such as ultrasound, on pregnant women unless there is a strong medical reason.

• Women who are breast-feeding should inform the radiologist and ask how to proceed. If necessary they may pump breast milk before the exam for use until the gadolinium contrast material has cleared from the body.

this is a link