Recent developments and prospects in high-field MR

摘要: During recent years much effort has been put into detecting and classifying disease states, MR imaging a very important tool in this respect. Up to now, increasing the gradient strength only strategy for meeting demands of advanced diagnostic applications. This is limited by physical, economic, andmedical considerations: technically difficult, associated with significant hardware costs risk inducing unwanted side effects such as peripheral neurostimulation. The main advantage high-field improved signal-to-noise ratio, which scales approximately linearly field from 1.5 T 3 T. signal can be used generatemore accurate spatial representation or speed up times, depending on specific application. Higher strengths change tissue contrast parameters. T1 relaxation time increased 30%, whereas T2 T2* times are decreased about 15% [37]. Increasing also doubles chemical shift susceptibility. spectroscopy benefits considerably spectral resolution possible MR, images acquired demonstrate enhanced sensitivity blood oxygen level-dependent (BOLD) effect [77]. On other hand, heating induced radiofrequency power disadvantage use TMR. In fact, RF absorption rate quadruples when increases most attempt circumvent these limitations parallel MRI.