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Magnetic resonance imaging (MRI) provides both accurate and partly functional scans without x-rays. The method is based on the reaction of the body’s hydrogen atoms in the device’s magnetic field. This method is suitable for the study of various patients, from newborn babies to elderly patients.
The MRI scanner has a scanning tunnel, the diameter of which is approximately 60cm. The tunnel is ventilated, illuminated and open at both ends. At times, the scanner produces relatively loud noises so the patient is provided a set of hearing protectors that can also be used to listen to the radio or music from a CD. The patient is also provided a call button to hold that he or she can use to contact the nurse, if necessary. A person accompanying the patient may stay in the examination room. An MRI takes approximately 15–45 minutes.
In most cases, you may eat and drink normally and take your regular medications before the scan. All metal objects, watches, jewellery, bank and credit cards and hearing aids are left outside the scanning room in a locked cabinet, because the strong magnetic field attracts metal and these items would smash against the tunnel wall.
If you have intracorporeal metal parts (cardiac pacemaker, prosthesis, surgical clip, shrapnel, pharmaceutical pump) you should contact the MRI unit before the procedure, because they may prevent the study. In most cases, joint prostheses do not prevent scanning. In addition, the examination should be avoided during early pregnancy. Before the MRI, you must complete a patient history form, which clarifies these issues.
A contrast medium injected into a vein in the hand can also be used in an MRI study. The contrast medium does not contain iodine. It provides information regarding the hyperaemia of tissues and improves the contrast of the scanned site, while facilitating the interpretation of the images to reach a reliable diagnosis.