Which magnet type used in MRI can be routinely turned on and off?

The type of magnet used in MRI that can be routinely turned on and off is the resistive magnet. Resistive magnets operate using electromagnetic coils that generate a magnetic field when an electric current passes through them. This ability to control the flow of current means that the magnetic field can be easily turned on or off and adjusted as needed.

Resistive magnets are particularly beneficial in situations where flexibility is required, such as in temporary installations or specialized scans. However, they typically produce a lower field strength compared to superconductive magnets and may require more power to maintain the magnetic field.

In contrast, permanent magnets provide a constant magnetic field without the need for electricity and cannot be turned off, while superconductive magnets require cooling to maintain their superconducting state and cannot be easily turned on and off. Fixed magnets, similarly to permanent magnets, maintain a constant magnetic field. Thus, the resistive magnet is uniquely suited for applications requiring routine operation and flexibility in the magnetic field.