ISSN 1590-8844 International Journal of Mechanics and Control, Vol. 11, No. 01, 2010 29 MR COMPATIBLE DEVICE FOR ACTIVE AND PASSIVE FOOT MOVEMENTS Guido Belforte* Gabriella Eula* Giuseppe Quaglia* Silvia Appendino* Franco Cauda** Katiuscia Sacco** * Department of Mechanics, Politecnico di Torino, Torino, Italy ** Department of Psychology, Università di Torino, Italy ABSTRACT The present paper presents a new MR compatible robotic device able to induce foot dorsiflexion and plantarflexion movements (‘passive’ patient mode), or to set and control for a series of parameters (force, amplitude) when the same movements are performed by the subject (‘active’ patient mode). Recent studies have demonstrated that the foot dorsiflexion is a critical component of the gait cycle; thus, ankle dorsiflexion/plantarflexion has been proposed as part of locomotor rehabilitation protocols, as well as a functional magnetic resonance imaging (fMRI) paradigm for defining brain activity relevant to gait. The principal aim of this work was to develop a robotic device to be used during fMRI testing, in pre- and post-locomotor therapy evaluations of cerebral activity. The same device can furthermore be used in the rehabilitation of neurological paretic patients, who need to practise foot movements and/or to relearn locomotor schemas. Design criteria and implementation are described, as well as the final prototype. Great concern was given to choice of materials (for MR compatibility) and to anthropometric dimensions (for patient adapting). Furthermore pneumatic circuit and control software are illustrated. Finally preliminary results obtained from a fMRI exam on a healthy subject are pointed up. Keywords: MR compatible, lower limb rehabilitation, robotics, neuroimaging 1 INTRODUCTION Functional magnetic resonance (fMRI) is an in vivo imaging technique which allows the mapping of active processes within the brain, thus revealing the cerebral areas involved in a particular motor or cognitive task. Most fMRI studies measure changes in blood oxygenation over time. Because blood oxygenation levels change rapidly following activity of neurons in a brain region, fMRI allows researchers to localize brain activity on a second-by-second basis and within oxygenation occur intrinsically as part of normal brain Contact author: Gabriella Eula 1 1 Politecnico di Torino, Department of Mechanics Corso Duca degli Abruzzi, 24 – 10129 Torino Italy E-mail: gabriella.eula@polito.it millimetres of its origin. Besides, as changes in blood physiology, fMRI is a non-invasive technique that can be repeated as many times as needed in the same individual. It is then used both for clinical aims and for research purposes. One of the main clinical applications concerns the detection of brain functional changes after rehabilitation programs in order to evaluate their efficacy. Robotics can greatly improve the accuracy of such medical evaluations, especially when the fMRI test is of motor type, i.e. where patient must achieve motor tasks or receive motor inputs during fMRI. For example, the motor rehabilitation of neurological paretic patients can be evaluated through the same fMRI motor task administered before and after the rehabilitation protocol: obviously, the force, the frequency and the amplitude of the limb movements must be identical in the two conditions. As