MRI FAQ

A: MRI is an imaging technique that employs a non-invasive strong magnetic field and radio waves to create images. Procedure is painless and does not involve any ionizing radiation. There is no known side effect.

However, there are safety concerns for the MRI environments. One should bear in mind that the magnetic field is ALWAYS ON. Metallic objects can be dangerous when they are being attracted by the strong magnetic field. It is necessary to take off all metallic possessions such as keys, watches, hairpins, earrings, etc. before entering the scan room. A safety checklist must be completed before starting a scan as safety measures.

Metallic implants or metallic foreign bodies also pose concerns on MRI safety. Please inform our staff if you have any metallic implants or prosthesis. Some common implants are listed as follows:

• Cardiac pacemaker/defibrillator
• Artificial heart valve
• Orthopedic prosthesis
• Cerebral aneurysm clips
• Neurostimulators
• Cochlear implants
• Newly placed orthopedics metallic implant or pin

A: MRI will not affect the dental fillings. However, metal components used in the dentures can influence the image quality.  Therefore, removeable dentures should be taken away before exam.

A: Depending on the examination requested by your doctor and the clinical indications, you may be required to have contrast medium injection for more information. Our staff will discuss with you before a contrast enhanced study.

A: Gadolinium-based MRI contrast medium is a safe drug. Reactions are uncommon and usually very mild. Please inform your doctor and our staff if you have previous history of allergy to gadolinium-based MRI contrast medium before examination. Steroid cover on the day before contrast MRI examination may be advised.

• Mild reactions: 
  Minor reactions such as headache, dizziness, nausea or vomiting, might occur in about 1% of patients.

• Severe reactions:
  Rarely! Gadolinium-based MRI contrast medium can cause severe reaction, such as convulsion, severe anaphylaxis and death, but is extremely rare. The chance of this fatal occurrence is about 1 in 400,000. For 1-7% of the patients with severely impaired renal function or on dialysis, gadolinium-based contrast media associated with nephrogenic systemic fibrosis and deaths have been reported. Fortunately, with the safety of the newest contrast media, these adverse effects are very rare.

Gadolinium may deposit in various structures of the brain following repeated injection of gadolinium-based MRI contrast media. To date, there is no proof that these gadolinium deposits in the brain have been associated with adverse health effects or pathological consequences.

A: MRI is considered a safe test, and no ionizing radiation is involved. However, long term biological effects of MRI examination on fetus are still not fully understood. MRI imaging of pregnant patient is carried out only when the patient’s doctor has decided that the advantages of MRI outweigh the potential risks.

Please inform your doctor and our staff if you are or may be pregnant before the examination.

A: Breast-feeding after the injection of Gadolinium-based MRI contrast medium is considered safe since only about 0.01% of the maternal Gadolinium dose is excreted into breast milk. Concerned mothers may discard milk for 24 hours after receiving contrast to avoid fetal exposure to contrast medium.

A: Most claustrophobic patients can still undergo an MRI examination with the assistance of our staff. An intercom system is available between patient and our staff for communication whilst an emergency call bell is also provided during the scan. Some patients may require mild sedation with medication prescribed by doctor. If needed, a family member is allowed to stay with the patient in the scan room throughout the examination after he/she is screened for metal on or in the body.

A: Yes, a requisition form signed by your doctor will provide us with your necessary clinical information; and we will tailor the examination accordingly.

A: The more information that our radiologist has when he reviews your study, the more specific the interpretation will be. Correlations with other studies are often helpful.

A: After the MRI examination, our radiologist will interpret your scan and issue an imaging report to your doctor who will then explain the findings and diagnosis to you.