Magnetic Resonance Imaging (MRI) is a medical imaging procedure for making images of the internal structures of the body. MRI scanners use strong magnetic fields and radio waves (radiofrequency energy) to make images. The signal in an MR image comes mainly from the protons in fat and water molecules in the body.
During an MRI exam, an electric current is passed through coiled wires to create a temporary magnetic field in a patient’s body. Radio waves are sent from and received by a transmitter/receiver in the machine, and these signals are used to make digital images of the scanned area of the body. A typical MRI scan last from 20 - 90 minutes, depending on the part of the body being imaged.
For some MRI exams, intravenous (IV) drugs, such as gadolinium-based contrast agents (GBCAs) are used to change the contrast of the MR image. Gadolinium-based contrast agents are rare earth metals that are usually given through an IV in the arm.
MRI Research Programs at FDA
- MHRA Safety Guidelines for Magnetic Resonance Imaging Equipment in Clinical Use (March 2015)
- FDA/CDER: Information on Gadolinium-Based Contrast Agents
- Safety Concerns with Implantable Infusion Pumps in the Magnetic Resonance (MR) Environment: FDA Safety Communication