Magnetic resonance imaging

Since its first proposal by Lauterbur in 1973 magnetic resonance imaging (MRI) has become one of the most advantageous diagnostic tools in medicine. It has led to the first industrial routine application of superconductive magnets. The authors outline the principles of magnetic resonance and how the spatial distribution of the nuclear magnetization in an object can be obtained by the application of magnetic field gradients. The state of the art of technology and parameters that influence contrast, resolution and noise in the image are described. The authors give examples of applications of MRI in soft tissue characterization, obtaining imaging times of less than a second, 3D imaging and the investigation of blood flow by magnetic resonance angiography. Spectroscopy can identify metabolites in vivo, but its clinical usefulness is still unclear because the low amounts of metabolites limit spatial resolution. Very recently functional imaging of brain activation has become possible, i.e. the measurement of local blood perfusion changes in the brain caused by sensory stimulation.