MRI, or magnetic resonance imaging, is a method used to visualize certain structures inside the body. An MRI can be performed on any area of the body, including an arm, a leg, the spine, the head, or the neck. MRIs are often used to assess injuries, joint conditions, internal organ issues, or to look for cancer. However, MRI is not effective for visualizing bone tissue, so other imaging methods (such as X-rays or CT scans) are typically used if there are concerns about the bones.
MRIs do not use any radiation. Instead, the scanner uses radio waves and strong magnetic fields to create images of various tissues inside the body. During an MRI, you will lie inside a tube for about 30 to 45 minutes. It is important to remain still during this time to ensure clear images. Some individuals may require a sedative to help them relax during the scan; your doctor can prescribe this if necessary. MRIs cannot be performed on individuals with certain types of metal in their bodies (such as some implants or shrapnel), as the strong magnetic fields can cause these materials to move.
A contrast dye is sometimes used to highlight specific types of tissue on an MRI. This procedure is called an enhanced MRI or an MRI with contrast. The dye is administered through an IV, and in most people, the kidneys clear it from the body within 24 hours. However, not all MRIs require contrast. MRIs can also be performed without contrast, referred to as unenhanced MRIs.
In some cases, it is useful to obtain MRI images of the same area both with and without contrast. By comparing the two sets of images, a radiologist can better differentiate between types of tissue. For this procedure, an initial MRI is performed without contrast. After the contrast dye is administered through an IV, a second set of MRI images is taken. This process is commonly referred to as an MRI with and without contrast, even though the non-contrast images are taken first.
