Robotic arm for magnetic resonance imaging guided interventions

The purpose of this work is to develop and evaluate the performance of a seven degree of freedom (DOF) remotely controlled manipulator to perform minimally invasive interventions with real-time magnetic resonance imaging (MRI) guidance inside clinical cylindrical scanners. Control of the device is based on MR images collected in real time during the procedure. A user interface fuses all MRI and non-MRI sensor information for man-in-the-loop control. The system offers both stereotactic and "free-hand" (manual) control. Stereotactic guidance uses pre-operatively collected multislice and/or three-dimensional MR images to set a path of insertion. Manual guidance uses a master/slave control device, which replicates the kinematics structure of the arm, to control its motion. In this mode, the manipulator sends instructions to the MRI scanner for on-the-fly continuous adjustment of the imaging plane position and orientation to image the end-effector and the interventional tool, as it maneuvers to acquire a target. The commanded movements of the manipulator are continuously checked by the control software whether they are within an allowable volume, extracted from the MR images, to avoid collision with the scanner or the subject. The device control is performed in real time with a host/target computer configuration. The manipulator compatibility with the MR environment and image-guided maneuvering was tested on a 1.5 Tesla MR scanner.