School of Biomedical Engineering & Imaging Sciences, King's College London, Rayne Institute, 4th Floor, Lambeth Wing, SE1 7EH, London, UK. siddharth.1.agarwal@kcl.ac.uk. School of Biomedical Engineering & Imaging Sciences, King's College London, Rayne Institute, 4th Floor, Lambeth Wing, SE1 7EH, London, UK. Leicester Medical School, University of Leicester, LE1 7RH, Leicester, UK. Centre for Medical Image Computing, Department of Computer Science, University College London, WC1V 6LJ, London, UK. School of Biomedical Engineering & Imaging Sciences, King's College London, Rayne Institute, 4th Floor, Lambeth Wing, SE1 7EH, London, UK. thomas.booth@kcl.ac.uk. Department of Neuroradiology, Ruskin Wing, King's College Hospital NHS Foundation Trust, SE5 9RS, London, UK. thomas.booth@kcl.ac.uk.