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Homogeneous MR images


MR image of a cylindrical water phantom (central axial slice). Above: One coil element is active; the others lead to severe inhomogeneities due to coupling effects (yellow). Below: By using this invention, the field distribution becomes more homogeneous.

Magnetic Resonance Imaging (MRI) at high magnetic fields up to 7 tesla allows a better image resolution, shorter measu-ring times and – thus – better diagnostics. A disadvantage is that, in the case of higher magnetic fields, the images are illuminated only inhomogeneously due to wave phenomena. With multi-channel transmit-receive coil systems it is, however, possible to avoid these image artefacts, but interferences due to mutual couplings between the elements of a multi-channel coil system complicate the precise compensation of signal voids in the MR image. This disturbing cross talk is effectively suppressed by means of a PTB invention. In the transmit and receive mode, it implements the electric current-controlled operation of each individual coil element so that the individual coil elements can be driven independently of each other. This decoupling scheme offers, first of all, an improvement of the existing high-field MR technology, but it could also lead to the development of novel applications such as, e.g., implantable MR coils. The instrument – for which EU and US patents have been granted – is a joint development of PTB and the University of Leipzig.