1. Computing Laboratory, University of Oxford, Wolfson Building, Parks Road, Oxford OX1 3DQ, UK
2. Bioengineering Institute, University of Auckland, Auckland 1142, New Zealand
3. Project ASCLEPIOS, INRIA, 2004, Route des Lucioles 06902, Sophia-Antipolis BP 93, France
4. Center for Computational Imaging and Simulation Technologies in Biomedicine (CISTIB), Universitat Pompeu Fabra, CIBER-Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona E08018, Spain