TY - JOUR A1 - Umutlu, L. A1 - Maderwald, S. A1 - Kinner, S. A1 - Kraff, O. A1 - Bitz, Andreas A1 - Orzada, S. A1 - Johst, S. A1 - Wrede, K. A1 - Forsting, M. A1 - Ladd, M. E. A1 - Lauenstein, T. C. A1 - Quick, H. H. T1 - First-pass contrast-enhanced renal MRA at 7 Tesla: initial results JF - European Radiology Y1 - 2013 U6 - http://dx.doi.org/10.1007/s00330-012-2666-0 SN - 1432-1084 VL - 23 IS - 4 SP - 1059 EP - 1066 PB - Springer CY - Berlin ER - TY - JOUR A1 - Orzada, S. A1 - Maderwald, S. A1 - Poser, B. A. A1 - Johst, S. A1 - Kannengiesser, S. A1 - Ladd, M. E. A1 - Bitz, Andreas T1 - Time-interleaved acquisition of modes: an analysis of SAR and image contrast implications JF - Magnetic Resonance in Medicine N2 - s the magnetic field strength and therefore the operational frequency in MRI are increased, the radiofrequency wavelength approaches the size of the human head/body, resulting in wave effects which cause signal decreases and dropouts. Especially, whole-body imaging at 7 T and higher is therefore challenging. Recently, an acquisition scheme called time-interleaved acquisition of modes has been proposed to tackle the inhomogeneity problems in high-field MRI. The basic premise is to excite two (or more) different Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-1 modes using static radiofrequency shimming in an interleaved acquisition, where the complementary radiofrequency patterns of the two modes can be exploited to improve overall signal homogeneity. In this work, the impact of time-interleaved acquisition of mode on image contrast as well as on time-averaged specific absorption rate is addressed in detail. Time-interleaved acquisition of mode is superior in Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-2 homogeneity compared with conventional radiofrequency shimming while being highly specific absorption rate efficient. Time-interleaved acquisition of modes can enable almost homogeneous high-field imaging throughout the entire field of view in PD, T2, and T2*-weighted imaging and, if a specified homogeneity criterion is met, in T1-weighted imaging as well. Y1 - 2012 U6 - http://dx.doi.org/10.1002/mrm.23081 SN - 1522-2594 VL - 67 IS - 4 SP - 1033 EP - 1041 PB - Wiley-Liss CY - New York ER - TY - CHAP A1 - Bitz, Andreas A1 - Kraff, O. A1 - Orzada, S. A1 - Maderwald, S. A1 - Brote, I. A1 - Johst, S. A1 - Ladd, E. T1 - Assessment of RF Safety of Transmit Coils at 7 Tesla by Experimental and Numerical Procedures (490.) T2 - 19th annual ISMRM scientific meeting and exhibition 2011 : Montreal, Quebec, Canada, 7 - 13 May 2011 Y1 - 2012 SN - 978-1-61839-284-8 IS - Volume 1 SP - 475 PB - Curran CY - Red Hook, NY ER -