Urology :: Magnetic Resonance Imaging (MRI)
What is an MRI?
An MRI is a diagnostic procedure that uses a combination of a large magnet, radiofrequencies and a computer to produce detailed images of organs and structures within the body.
How does an MRI scan work?
The MRI machine is a large, tube-shaped machine that creates a strong magnetic field around the patient. The magnetic field, along with a radiofrequency, alters the hydrogen atoms' natural alignment in the body. Computers are then used to form a two-dimensional (2D) image of a body structure or organ based on the activity of the hydrogen atoms. Cross-sectional views can be obtained to reveal further details. MRI does not use radiation.
Due to the use of the strong magnet, MRI cannot be performed on patients with implanted pacemakers, cochlear implants, certain prosthetic devices, implanted drug infusion pumps, neurostimulators, bone-growth stimulators, certain intrauterine contraceptive devices, or any other type of iron-based metal implants. Guidelines from the radiology department will be given to the patient and family prior to the study.
How is an MRI performed?
An MRI may be performed on an outpatient basis, or as part of inpatient care.
- Because of the strong magnetic field, the patient must remove all jewelry and metal objects, such as hairpins or barrettes, hearing aids, eyeglasses, and dental pieces.
- If a contrast medication and/or sedative are to be given by an intravenous line (IV), an IV line will be started in the hand or arm. If the contrast is to be taken by mouth, the patient will be given the contrast to swallow. (Young children may be sedated for the MRI to prevent them from moving around during the test.)
- The patient will lie on a table that slides into a tunnel in the scanner.
- The MRI staff will be in another room where the scanner controls are located. However, the patient will be in constant sight of the staff through a window. Speakers inside the scanner will enable the staff to communicate with and hear the patient. The patient will have a call bell so that he or she can let the staff know if he or she has any problems during the procedure.
- During the scanning process, a clicking noise will sound as the magnetic field is created and pulses of radio waves are sent from the scanner. The patient may be given headphones to wear to help block out the noises from the MRI scanner and hear any messages or instructions from the technologist.
- It is important that the patient remain very still during the examination.
- At intervals, the patient may be instructed to hold his or her breath for a few seconds, depending on the body part being examined. The patient should not have to hold his or her breath for longer than a few seconds, so this should not be uncomfortable.
- The technologist will be watching the patient at all times and will be in constant communication.
Is an MRI dangerous?
An MRI is a safe, noninvasive procedure, and unlike X-rays or CT scans, MRI does not use radiation.