Magnetic Resonance Imaging (MRI) is a non-invasive imaging technique that uses a strong magnetic field, radio waves, and a computer to produce detailed images of organs, soft tissues, and other structures within the body. It is one of the most commonly used imaging techniques in the medical field, mainly because of its ability to generate high-resolution images without the use of radiation.

Magnetic Field

The magnetic field used in MRI is produced by a powerful magnet, which is usually made of superconducting material. This material has the ability to conduct electricity without resistance. This magnetic field is composed of two primary components: a static magnetic field, and a time-varying radio frequency field. The static field is produced by a large superconducting magnet and is typically either 1.5 or 3.0 Tesla in strength. To give you an idea of this strength, 1.5T is 30,000 times stronger than the magnetic field produced by Earth. This field is used to align the hydrogen atoms in the body in a uniform orientation and is responsible for the creation of the images.

The time-varying radio frequency field is the second component of the MRI scanner and is used to excite the hydrogen atoms in the body and create a signal which is then detected by the scanner. The frequency and strength of the radio frequency field are determined by the type and size of the scanner and can vary from 0.4 to 64 MHz.

Measuring the Field

In order to measure the magnetic field of an MRI scanner, several different techniques are used. These include proton resonance frequency (PRF) measurements, which measure the frequency of the static magnetic field, and magnetic resonance frequency (MRF) measurements, which measure the frequency of the time-varying radio frequency field.

The PRF measurements are used to determine the accuracy of the static magnetic field, while the MRF measurements are used to determine the accuracy of the time-varying radio frequency field. The measurements are typically performed at various points throughout the scanner and at different depths within the body in order to ensure that the magnetic field is uniform and of the correct strength.

MRI magnetic measurements are an important part of the MRI scanning process, as they ensure that the scanner is functioning properly and that the images generated are of the highest quality. In addition, these measurements are also used to monitor the safety of the scanner, as they provide an indication of the strength of the magnetic fields used in the scanning process.