Functional magnetic resonance imaging (fMRI) is often used to enhance visualization and provide target localization during the planning phase of neurosurgical procedures. Although parametric maps have been used to identify areas of eloquent cortex such as the primary (S1) and secondary (S2) somatosensory areas for tumor surgery, to date, few fMRI methods exist to localize subcortical targets for surgical interventions used to treat movement disorders. The scanning time required to obtain statistically significant functional signals must be balanced against the possibility of movement artifacts and patient discomfort. We propose a vibrotactile stimulation technique to activate the somatosensory pathway for neurosurgical planning and perform a sensitivity analysis to determine the amount of time required to achieve significant activations of S1, S2, and sensory thalamus in individual subjects. Bilateral stimulation experiments were carried out on two MRI scanners (n = 13 at 1.5 T; n = 5 at 3.0 T). The analysis demonstrates that statistically significant functional activations can be achieved in clinically acceptable times: 16 min at 1.5 T (26/26 experiments) and 6 min at 3.0 T (10/10) for S1 activations; 24 min at 1.5 T (22/26) and 18 min at 3.0 T for S2 activations (9/10); and 32 min at 1.5 T (15/26) and 18 min at 3.0 T (10/10) for activation of thalamic nuclei. These results demonstrate that S1 and S2 activations are robust at 1.5 and 3.0 T, and that robust thalamic activations in individual subjects are possible at 3.0 T. These techniques demonstrate that this technique can be used for preoperative planning for surgical candidates.

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Pre-operative neurosurgical planning often uses data from functional magnetic resonance imaging (fMRI) to identify areas of eloquent cortex, such as the primary and secondary somatosensory cortices, to be spared during surgery. However, the in-vivo visualization of subcortical neurosurgical targets has typically involved the warping of subcortical atlases or T2-and diffusion-weighted imaging techniques to help define the anatomical borders. We propose a novel vibrotactile stimulation technique to activate the somatosensory pathway, and particularly the sensory thalamus. Experiments were executed on two MRI scanners (1.5T and 3.0T). A sensitivity analysis demonstrated that statistically significant functional activations of the sensory thalamus can be in achieved in clinically acceptable time (32 minutes at 1.5T and 12 minutes at 3.0T), thus enabling this technique to be used for pre-operative planning in patients.