Patient tableThe narrow table that slides into the bore.
RF coil (radiofrequency coil)Placed near the body part. It sends and receives radio waves.
Control roomThe room next door, where the operator runs the scanner.
ComputerIt controls the scanner and turns the signals into pictures.
IntercomThe person being scanned and the operator talk through it.
Cut across 3
Main magnetThe large ring of wire coils that makes the strong field.
Liquid heliumIt keeps the coils of the main magnet very cold.
Gradient coilsCoils that change the magnetic field from place to place.
How this list was compiled: Every name checked on 2026-09-30, a name kept only where two of these use it: (1) National High Magnetic Field Laboratory, MRI: A Guided Tour, https://nationalmaglab.org/magnet-academy/read-science-stories/science-simplified/mri-a-guided-tour/ (the bore; the main magnet and its coils in liquid helium; three gradient magnets and the noise they make when switched on and off; the RF coil, a radio transceiver placed by the technologist; the technologist in the control room, talking through an intercom); (2) Wikipedia, Magnetic resonance imaging and Physics of magnetic resonance imaging, text only, https://en.wikipedia.org/wiki/Magnetic_resonance_imaging and https://en.wikipedia.org/wiki/Physics_of_magnetic_resonance_imaging (the main magnet, the shim coils, the gradient system and the RF system, controlled by one or more computers; coils of superconducting wire immersed in liquid helium; the bore; radio frequency coils); (3) MedlinePlus Medical Encyclopedia, MRI, https://medlineplus.gov/ency/article/003335.htm (a narrow table that slides into a large tunnel-shaped scanner; small devices called coils placed around the head, arm or leg; the operator watching from another room; an intercom; a computer); (4) NHS, MRI scan: what happens, https://www.nhs.uk/tests-and-treatments/mri-scan/what-happens/ (a large machine pierced by a short tunnel; its flat bed slides through the scanner; the radiographer controls the scanner from another room); (5) National Institute of Biomedical Imaging and Bioengineering (NIH), Magnetic Resonance Imaging, https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging-mri (the patient is placed inside a large magnet). Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; no photograph or plate followed. Licence: own work
How it works
The parts of an MRI machine are a large magnet with a tunnel through it, a table that slides into the tunnel, and coils that send and receive radio waves. Two drawings give the names only.
Read the full guide
Outside, then inside
The first drawing is the scanner room: the bore, the patient table, an RF coil on the table, and on the wall an intercom and the window of the control room, where the computer is. The second drawing cuts the scanner across. The main magnet is a ring of wire coils that sits in liquid helium. Inside it are the gradient coils, and in the middle is the bore.
The knocking noise of a scan comes from the gradient coils being switched on and off.
This page names parts only. It is not medical advice.
Questions and answers
What are the main parts of an MRI machine?
The main magnet, the gradient coils and the radiofrequency coils, all controlled by a computer. The person being scanned lies on a table that slides into the bore, the tunnel through the magnet.
What is the tube of an MRI machine called?
The bore. It is the tunnel through the middle of the scanner, inside the ring of the main magnet.
Why does an MRI machine use liquid helium?
The main magnet is made of coils of superconducting wire. Liquid helium keeps the wire cold enough to carry an electric current with no resistance.
What is an RF coil in an MRI machine?
A radiofrequency coil sends radio waves and picks up the signal that comes back. Small ones are placed around the part being scanned, such as the head, an arm or a leg.