Simultaneous B1+ homogenisation and SAR hotspot suppression by a phased array MR transmit coil.
van den Berg C, Kroeze H, Lagendijk J, Bartels L, van den Bergen B
University Medical Centre
In this study it is demonstrated that in 3 Tesla whole-body MR imaging, quadrature performance is severely deteriorated. FDTD simulations with four different patient models demonstrated severe B1+ non-uniformity and elevated SAR deposition, especially for obese patients. These effects can be explained by the dielectric interaction of an elliptical geometry with a circularly polarized RF field. A phased array transmit coil is able to correct for this effect and suppress B1+ non-uniformity and SAR hotspots. This technique would allow higher flip angles and/or higher RF duty cycles at 3T while gaining in flip angle uniformity.