MRI Compatible Robot Systems for Medical Intervention

Abstract

Magnetic resonance imaging (MRI) is a non-invasive medical imaging tool that helps physicians diagnose and treat medical conditions. It offers excellent visualization of softtissue in any imaging plane without using of iodinated contrast agent or ionizing radiation. In addition to anatomical morphology, MRI can also provide functional information. With novel fast imaging technologies, MRI became an imaging tool for guiding and monitoring various interventions and biopsy procedures on various organs including the brain, breast, prostate, liver and spine (Jolesz, 1998, Melzer & Seibel, 1999). High performance magnetic field gradients, multi-channel receivers, and advanced reconstruction systems improve the clinical applicability of real time MRI procedures (Nayak et al., 2004, Bock et al., 2004, Guttman et al., 2003, Lederman, 2005). Modern scanners designed for the interventional environment can provide real-time images of acceptable quality in excess of 10 frames per second. As a result, real-time MRI (rtMRI) is becoming an attractive method for many minimally invasive cardiac interventions (Kuehne et al., 2003, Raval et al., 2006, Henk et al., 2005, McVeigh et al., 2006, Horvath et al., 2007). However the confined physical space of MRI scanner challenges medical intervention, even the magnets with open architecture provide only a limited working space, at the expense of image quality. The use of robots inside the MRI scanner is a very attractive solution: a robot manipulates the intervention instruments while MR images continuously give feedback of the position of the instruments which are controlled by the robot. MR compatible robotic systems have been researched and developed for prostate biopsy and brachytherapy (Chinzei et al., 2000, Krieger et al., 2005, Fischer et al., 2006, Stoianovici et al., 2007a), breast intervention (Kaiser et al., 2000, Larson et al., 2004), interventional spinal procedure (Hempel et al., 2003), neurosurgery (Masamune et al., 1995, Koseki et al., 2002), interventional liver therapy (Hata et al., 2005, Kim et al., 2002), and cardiac intervention (Li et al., 2008). Design of a system operating inside or close to the bore of a high field MRI scanner is of significant complexity. Due to the strong magnetic field of the MRI, standard materials, sensors and actuators cannot be employed. Due to the confined space of MRI bore, the mechanical design should be compact and simultaneously functional. In this chapter, we 22