• 7 T;
  • renal angiography;
  • non-contrast enhanced;
  • Bmath image shimming;
  • kidney


The purpose of this study was to detail a strategy for performing non-contrast enhanced renal magnetic resonance angiography studies at 7.0 T. It is demonstrated that with proper Bmath image management, these studies can be successfully performed at ultrahigh field within local specific absorption rate constraints. An inversion prepared gradient echo acquisition, standard for non-contrast renal magnetic resonance angiography studies, required radiofrequency pulse specific Bmath image shimming solutions to be dynamically applied to address the field dependent increases in both B0 and Bmath image inhomogeneity as well as to accommodate limitation in available power. By using more efficient Bmath image shimming solutions for the inversion preparation and more homogeneous solutions for the excitation, high quality images of the renal arteries were obtained without venous and background signal artifacts while working within hardware and safety constraints. Finite difference time domain simulations confirmed in vivo measurements with respect to Bmath image distributions and homogeneity for the range of shimming strategies used and allowed the calculation of peak local specific absorption rate values normalized by input power and Bmath image. Increasing Bmath image homogeneity was accompanied by decreasing local specific absorption rate per Watt and increasing maximum local specific absorption rate per [Bmath image]2, which must be considered, along with body size and respiratory rate, when finalizing acquisition parameters for a given individual. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.