St Bartholomew’s Hospital and Queen Mary University of London 1 article published in JoVE Engineering Three-Dimensional Ultrasonic Needle Tip Tracking with a Fiber-Optic Ultrasound Receiver Wenfeng Xia1,2, Simeon J. West3, Malcolm C. Finlay2,4, Rosalind Pratt5,6, Sunish Mathews1,2, Jean-Martial Mari7, Sebastien Ourselin1,2,6, Anna L. David1,5,8,9, Adrien E. Desjardins1,2 1Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, 2Department of Medical Physics and Biomedical Engineering, University College London, 3Department of Anaesthesia, University College Hospital, 4St Bartholomew's Hospital and Queen Mary University of London, 5Institute for Women's Health, University College London, 6Centre for Medical Imaging Computing, University College London, 7GePaSud, University of French Polynesia, 8Department of Development and Regeneration, KU Leuven (Katholieke Universiteit), 9NIHR University College London Hospitals Biomedical Research Centre Accurate and efficient visualization of invasive medical devices is extremely important in many ultrasound-guided minimally invasive procedures. Here, a method for localizing the spatial position of a needle tip relative to the ultrasound imaging probe is presented.