1. Centre for Advanced Biomedical Imaging (CABI), Department of Medicine, University College London, London WC1E 6DD, UK
2. Healthcare Biomagnetics Laboratory, University College London, 21 Albemarle Street, London, W1S 4BS, UK
3. Resonant Circuits Limited, 21 Albemarle Street, London, W1S 4BS, UK
4. School of Life Science, Pharmacy & Chemistry, Kingston University, Penrhyn Road, Kingston upon Thames, KT1 2EE, UK