Unlocking the potential of ultra-high-field MRI th.. (MRexcite)
Unlocking the potential of ultra-high-field MRI through manipulation of radiofrequency excitation fields in human tissue
Start date: May 1, 2012,
End date: Apr 30, 2017
In the past three decades, magnetic resonance imaging (MRI) has become a vital tool for clinical diagnosis and research. A major current trend is the introduction of magnets with much more powerful static magnetic fields, including magnets at 7 Tesla (7T) and higher. Advantages of higher magnetic fields include higher signal-to-noise ratios enabling improved spatial and temporal resolution, and new, unique tissue contrasts due to enhanced sensitivity to tissue susceptibility differences.Unfortunately, the radiofrequency (RF) fields used to excite tissue at higher magnetic fields are subject to interference and penetration effects, leading to signal dropouts which vary from subject to subject depending on body habitus. These effects imply that the inherent advantages of 7T often cannot be leveraged to realise practical imaging benefits. A fair evaluation of the diagnostic potential of 7T cannot be achieved, as image quality improvements are handicapped and often counteracted by these unresolved technical hurdles. 7T MRI cannot be considered for routine clinical use or even effectively evaluated for such use until these hurdles have been overcome.Preliminary research indicates that these effects can be addressed by use of parallel transmission strategies. The goal of the proposed project is to develop a highly optimized multi-channel transmit/receive RF coil for body MRI at 7T. This coil should then be used to exploit and manipulate the complex RF field patterns at 7T using parallel transmission approaches. In contrast to previous approaches, a hybrid method including both static and dynamic shimming of the RF field will be investigated. We hypothesise that such an approach would greatly enhance the flexibility of RF manipulation while limiting overall system complexity. It can be conjectured based on the known properties of ultra-high-field MRI that success would have ground-breaking impact on the diagnosis and characterisation of manifold disease processes.
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