Preliminary studies for using magnetic resonance imaging systems as a mean of propulsion for microrobots in blood vessels and evaluation of ferromagnetic artefacts

A prototype for a magnetically controlled microrobot for applications in blood vessels is being developed. A strong and variable driving magnetic field exerts propulsion forces in three dimensions to a ferromagnetic core embedded onto the microrobot. Magnetic resonance imaging (MRI) systems are being considered as they provide the required magnetic fields and controls. Their imaging capabilities could also be used to track the displacements of the robots, providing position feedback informations. The paper describes tests made for spin echo and gradient echo sequences. They show that ferromagnetic materials cause imaging distortions (artefacts) several times larger than the size of the ferromagnetic core. It is critical to retrieve the robot's position from the distorted image but, the elimination or reduction of such ferromagnetic artefacts is currently a serious problem. Therefore, alternative solutions to the imaging problems like artefact cancelation or artefact pattern tracking softwares need to be developed.