The indications for performing an MRI scan are covered under each organ system being investigated.
An MRI scan takes longer than a CT scan and requires you to lie in a tunnel. A non contrast MRI of the brain takes about 15 minutes whereas a MRI of the spine or breasts with gadolinium contrast material may last for up to 1 hour.
During this time the patient needs to lie still to avoid motion artefact. Some patients may suffer from claustrophobia in which case sedation will be given. Should sedation be needed, the patient will not be allowed to drive home.
An intravenous contrast material, gadolinium, may be used in selected circumstance. This allows enhancement of the vascular structures and other abnormality. Should this be necessary, the radiologist will come into the room during the procedure and inject through a small needle placed in the forearm.
Communication is possible with the radiographer during the procedure should the patient experience any discomfort.
Patients are usually scanned on their backs but sometimes other positions are adopted. The scans are fast and the patient does not lie in a tunnel as with MRI. The procedure is painless other than a small needle prick when contrast is injected. When iodine contrast material is used, it is not uncommon to get a metallic taste in your mouth and experience a ‘hot flush.’ This rapidly disappears.
The Radiologist is equipped to manage any adverse contrast reaction. The needle will be removed after the scan is completed. Results will be available the same day.
Patients with a cardiac pacemaker or certain metallic prosthesis cannot be imaged with MRI due to the magnetic field. The patient must inform the radiographers of any such devices before the scan is booked. Most metals used today are MRI friendly.
The results will be available on the same day from your doctor.
Magnetic resonance imaging (MRI) uses a magnetic field, radio frequency pulses and a computer to produce detailed pictures of internal body structures, to evaluate for the presence of abnormalities. Unlike conventional x-ray examinations and computed tomography (CT) scans, MRI does not depend on ionizing radiation (X rays).
MRI of the breast is not a replacement for mammography and ultrasound imaging, but rather a supplemental tool that has many important uses, including: screening in women at high risk for breast cancer, determining the extent of cancer after a new diagnosis of breast cancer, follow up following breast cancer treatment, including surgery, radiation and chemotherapy and evaluating breast implants.
The best time for a breast MRI is between day 6 and 12 of the menstrual cycle (day 1 is the day your period starts) and 4 to 6 weeks after stopping any hormone replacement therapy (HRT).
On the day of the appointment, please bring any mammogram, breast ultrasound and biopsy results with you to the radiology department. You may be asked to wear a disposable gown and surgical bra during the exam, and tape small oil filled capsules over your nipples as an aid for localisation.
The radiology staff will take a brief medical history and should know if you have any serious health problems or if you have recently had surgery. If there is a history of kidney disease, it may be necessary to perform a blood test to determine whether the kidneys are functioning adequately. Women should always inform the staff if there is any possibility that they are pregnant.
If you have claustrophobia (fear of enclosed spaces) or anxiety, you may want to ask your doctor for a prescription for a mild sedative prior to the scheduled examination, however it is important that you remain awake and co-operative during the MRI.
Patients with the following implants should not enter the MRI scanning area unless explicitly instructed to do so by a radiologist or technologist who is aware of the presence of any of the following: internal cardiac defibrillator or pacemaker, cochlear (ear) implant, some types of clips used on brain aneurysms, metal coils placed within blood vessels, artificial heart valves, implanted drug infusion ports or nerve stimulators and artificial limbs or metallic joint prostheses.
The MRI unit is a large cylinder-shaped tube surrounded by a circular magnet. You will lie on a moveable examination table that slides into the center of the magnet.
Before the examination starts, the radiologist will insert an intravenous (IV) line into a vein in your hand or arm. A saline solution will drip slowly through the IV to prevent blockage of the line until the contrast material is injected half way through the scan.
For an MRI of the breast, you will lie prone (face down) on a platform specially designed with openings to accommodate your breasts, and allow them to be imaged without compression. It is important to remain very still throughout the exam and we will try to make you as comfortable as possible.
MRI exams include multiple runs (sequences), some of which may last several minutes and the total imaging session lasts approximately 45 minutes. You will know when images are being recorded because you will hear loud tapping or thumping sounds when the coils that generate the radiofrequency pulses are activated. You may be offered or you may request earplugs to reduce the noise of the MRI scanner. You will usually be alone in the exam room during the MRI procedure. However, the technologist will be able to see, hear and speak with you at all times using a two-way intercom. In some circumstances we may allow a friend or parent to stay in the room as long as they are also screened for safety in the magnetic environment.
When the contrast material is injected, it is normal to feel coolness and a flushing sensation for a minute or two.
A radiologist, a doctor specifically trained to supervise and interpret radiology examinations, will analyze the images and send a CD and report to your referring doctor, who will discuss the results with you.
If you have any further questions, please contact our department.