How does an MRI scanner generate a magnetic field?

An MRI scanner generates a magnetic field using superconducting coils made of niobium-titanium.

MRI scanners use a strong magnetic field to align the protons in the body's hydrogen atoms. This magnetic field is generated by superconducting coils made of niobium-titanium, which are cooled to a temperature of -269°C using liquid helium. When cooled to this temperature, the coils become superconducting, meaning they can conduct electricity with zero resistance. This allows a large current to flow through the coils, creating a strong magnetic field.

The strength of the magnetic field is measured in tesla (T), with most MRI scanners operating at 1.5T or 3T. The higher the magnetic field strength, the clearer the resulting images. However, higher field strengths also require more powerful and expensive magnets, as well as more complex cooling systems.

In addition to the main magnetic field, MRI scanners also use gradient coils to create small variations in the magnetic field. These variations are used to spatially encode the signals received from the body, allowing the scanner to create detailed 3D images.

Overall, the magnetic field generated by an MRI scanner is a crucial component of the imaging process, allowing for the creation of detailed images of the body's internal structures.