A newly developed removable dental device for fused 3-D MRI/MEG imaging

Recently 3-D imaging techniques have been used to shed light on the role of abnormal brain functions in such conditions as nocturnal bruxism and orofacial pain. In order to achieve precise 3-D image fusion between magnetic resonance images (MRI) and magnetoencephalography (MEG) data, we developed a removable dental device which attaches rigidly to the teeth. Using this device, correlation of MEG and MRI data points was achieved by the co- registration of 3 or more fiducial points. Using a Polhemus 3-space digitizer the locations of the points were registered on MEG and then a small amount of high-water-content material was placed at each point for registering these same points on MRI. The mean reproducibility of interpoint distances, determined for 2 subjects, was between 0.59 and 0.82 mm. Using a Monte Carlo statistical analysis we determined that the accuracy of a posterior projection from the fiducial points to any point within the strata of the brain is ±3.3 mm. The value of this device is that it permits reasonably precise and repeatable co-registration of these points and yet it is easily removed and replaced by the patient. Obviously such a device could also be adapted for use in diagnosis and analysis of brain functions related with other various sensory and motor functions (e.g., taste, pain, clenching) in maxillofacial region using MRI and MEG.