When Is MRI Used?
MRI scan has become the gold standard in imaging the extremities, especially the joints. Some radiology departments use CT scan as the preferred screening test for imaging the brain, but most radiologists consider MRI scan to be the best choice for imaging the upper spine and lower back. CT and MRI are equally useful for the neck. For chest and abdomen, CT scan may be more effective, however, new applications for MRI are constantly being developed.
Ultrasound is still the best way to examine the female pelvis, although MRI scan may be used to image the uterus and ovaries, and CT is helpful in certain cases. Ultrasound often is used to examine the scrotum; however, MRI and radionuclide imaging may also be used.
MRI Risks and Complications
During an MRI scan, the patient is placed inside an enormously powerful magnet, so he or she must not have anything on his or her person that could be attracted to this magnet. What about little pieces of metal inside the body that the patient may or may not know about? For example, tiny metal filings that may have penetrated the skin years ago, or tiny metal clips that were used to tie off a brain aneurysm, and so on? For a full list of MRI risks, patients should be sure to speak with a representative of the MRI facility at which the study will be performed. The MRI technologist can answer any additional questions.
As is the case in CT scan, an MRI may require the injection of intravenous contrast. The most commonly used dye is gadolinium, which basically does to MRI what iodine does to CT. The good news is that unlike the CT dye, with its rare complication, complications from gadolinium are even more rare, and gadolinium can be injected by a thin needle that hurts less.
What Actually Happens during MRI?
MRI scan can be an unpleasant test. Patients who are obese may have additional difficulties during MRI. In most cases, patients are confined in a tight space within the magnet and are asked not to move.
Some patients are too claustrophobic to undergo MRI. The MRI scanner is confining and noisy. Some departments give patients earphones with music to help block the noise and distract them. Newer MRI gantries have a much wider bore and are much less confining. If you receive contrast, the technologist, nurse, or radiologist will generally inject it through a small gage needle that should not be particularly painful.