1. Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, 49 Convent Drive, Bethesda, Maryland 20892-5772, USA
2. Laboratoire Interdisciplinaire de Physique CNRS, Université Grenoble Alpes, F-38402 Saint Martin d’Hères Cedex, France