Feasibility of simultaneous respiratory function monitoring and determination of respiratory-related intrahepatic vessel excursion using the LifeShirtk system Elliot Levy a, * , Marc Kalis a , Minh Vo b , David Lindisch b , Kevin Cleary b a Department of Radiology, MedStar Georgetown University Hospital, Washington, DC, USA b Imaging Science and Information Systems Center, Department of Radiology, Georgetown University, Washington, DC, USA Abstract. The purpose of this study was to investigate the feasibility of using the LifeShirtk ambulatory functional monitoring system to determine correlations between respiratory functional parameters and liver motion for minimally invasive hepatic interventions. D 2004 Published by Elsevier B.V. Keywords: Respiratory monitoring; Liver ultrasound; Liver motion 1. Introduction Accurate percutaneous placement of needles within the liver is an essential part of a large variety of procedures. Currently, lesions or vessels are targeted within the liver using real-time ultrasound imaging, static computed tomography (CT) or CT fluoroscopy, or MRI. Finally, some procedures such as transhepatic portography, intrahepatic portosyste- mic shunt placement (TIPS), or transhepatic biliary drainage are most often performed blindly until a target vessel or duct is successfully punctured after multiple attempts. In general, intrahepatic needle manipulation is restricted to short time periods during breath holds in the conscious patient in order to minimize the risk of trauma or laceration due to fixed needle position during respiratory-related target organ excursions. In separate experiments, we are evaluating an electromagnetic tracking-based guidance system for intrahepatic interventions. Our algorithm features an internal fiducial with which we monitor respiratory-related hepatic motion to detect the short pause in organ motion which is observed at the end of each exhalation. Needle movements are restricted to this short, regularly observed end-expiratory pause in organ motion. Alternatively, the motion of skin 0531-5131/ D 2004 Published by Elsevier B.V. doi:10.1016/j.ics.2004.03.338 * Corresponding author. E-mail address: levye@gunet.georgetown.edu (E. Levy). www.ics-elsevier.com International Congress Series 1268 (2004) 764 – 769