Magnetic Resonance Imaging (MRI)

Magnetic Resonance Imaging (MRI)

What is MRI?

• Magnetic resonance imaging (MRI) is an imaging technique used in radiology to investigate the anatomy and function of the body. MRI scanners use strong magnetic fields and radio waves to form detailed images that allow radiologists to evaluate various parts of the body and determine the presence of certain diseases.
• MRI is used to help the clinician diagnose a wide range of diseases such as stroke, infection and tumors.

How is it done?

• The procedure is performed by a licensed radiologic technologist under the supervision of a radiologist.
• MRI requires a strong uniform magnetic field around the area to be imaged. This magnetic field interacts with the hydrogen atoms in our body producing radio frequency signals which are then picked-up by coils and converted by a computer into cross-sectional images.
• The interpreting radiologist can then view these images to make a diagnosis.

How long does it take?

• MRI scanning time varies, depending on the procedure and the body part to be examined.
• Routine non-contrast procedures generally take between 30 minutes to one hour.
• Contrast procedure and special procedures can last anywhere between one or two hours.

What are the preparations?

• You will be asked to arrive one hour prior to scheduled procedure.
• Avoid clothing with snaps, zippers, metallic studs, rivets or accents.
• For intravenous contrast procedures, a normal serum creatinine result taken within 10 days of the scheduled procedure is required.
• For contrast procedures either intravenously or orally administered:

-          You may be asked to eat or drink anything for a few hours beforehand.

• Please inform your attending physician or radiologist if you have any metallic objects in your body. These objects may react with the strong magnetic field surrounding the MRI. Clearance from your attending physician may be required prior to the procedure.

-          Surgical devices (surgical clips, aneurysm coils and clips, vascular clips and coils)

-          Pacemaker

-          Cochlear (ear) implants

-          Dental implants (braces, fillings, bridgework)

-          Orthopedic devices (joint replacement, metal rods and screws)

-          Foreign objects (bullet or bullet fragments, body piercings)

-          Tattoos

• Inform your attending physician if you are pregnant.
• Inform your attending physician if have any history of claustrophobia (fear of enclosed spaces) and/or anxiety. Medications or sedatives may be given by your attending physician.
• Do not forget to bring your doctor’s request and previous CT, MRI or ultrasound examinations if available.

What can you expect at the MRI Suite?

• You will be asked to arrive one hour prior to the scheduled procedure for patient registration followed by a short interview and physical exam.
• For intravenous contrast studies, a needle will be inserted into your vein.
• You will be REQUIRED to remove any metallic objects in your person (keys, coins, credit cards, jewelry watches, and cell phones among others).
• You may be required to remove your top, bra or pants and change into a hospital gown.
• The radiologic technologist begins by positioning you on the movable examination table.
• Straps and pillows will be used to stabilize you and help you remain still during the study.
• You may also be asked to hold your breath during the scan. (Any motion, whether breathing or body movements, can lead to blurring of the images resulting in a longer scanning time).
• Devices called “coils” may be placed around or adjacent to the area of the body being studied. These may be restrictive and sometimes uncomfortable but are necessary to acquire the images.
• The table will then be moved into the magnet of the MRI scanner.
• You will be along in the MRI room during the procedure. In special circumstances, a relative may be allowed in the room.
• Loud mechanical noises will be heard during the examination. Some patients also complain of heat while being scanned.
• The radiologic technologist and radiologist will be able to see you, and hear and speak with you throughout the procedure through the two-way glass window, built-in intercom and CCTV system. A call button is available for any concerns during the procedure.
• For intravenous contrast studies, the contrast will be injected into your vein and additional scans will be taken.
• When the examination is completed, you may be asked to wait in case additional images are needed.
• If you received contrast material, you will be given special home instructions.

What are the benefits of the procedure?

• MRI does not emit any ionizing radiation.

What are the risks of the procedure?

• Metallic objects (surgical, orthopedic and/or dental devices) within the body can cause heat or pain when placed within the magnetic field of the MRI machine. Although rare, movement of these objects is a possibility.
• Claustrophobia (fear of enclosed spaces) and/or anxiety.
• Pregnant women usually are advised not to have an MRI exam during the first trimester unless medically necessary.
• Large individuals may not fit into the opening of certain types of MRI machines.
• Pain or discomfort from intravenous line (IV) insertion and injection.
• Although rare, there may be serious allergic reaction to the contrast material.

What are the possible alternatives?

• Depending on the body part to be examined, other imaging modalities such as x-ray, ultrasound or CT scan may be requested.
• For patients who cannot tolerate the prolonged scanning time and/or anxious/claustrophobic patients, mild sedation may be requested by your attending physician.

When will the results be ready?

• For routine procedures, results will be ready 24 hours after the procedure.
• For special procedures and difficult cases, review of previous imaging studies and/or consult with the attending physician may be necessary for optimal interpretation, requiring more time.

How can The Medical City help you?

The Medical City has a complete roster of competent radiologists capable of performing and interpreting different imaging modalities and radiologic procedures.

For scheduling and other inquiries, please contact:

DEPARTMENT OF RADIOLOGY

Tel. no. (632) 988-1000 / (632) 988-7000 ext. 6337

CENTER FOR PATIENT PARTNERSHIP

Tel. no. (632) 988-1000 / (632) 988-7000 ext. 6444

References:

Fundamentals of Diagnostic Radiology, 4^th Ed 2012, Brant and Helms

American College of Radiologic Guidelines

Philippine College of Radiologic Guidelines

TMC – Department of Radiology Operation Policies

Note: This information is not intended to be used as a substitute for professional medical advise, diagnosis or treatment.   If you or someone you know have any of the symptoms mentioned above, it is advisable to seek professional help.