Stereotactic targeting of the ventrointermediate nucleus of the thalamus by direct visualization with high-field MRI.

To evaluate the ability of high-field MRI to consistently produce high-resolution, anatomical images of the thalamic ventrointermediate nucleus (Vim) suitable for stereotactic targeting. MR images of the thalamus of patients treated for essential tremor were acquired prior to treatment using a 3-tesla MR system. Similar images were acquired in 6 volunteers using, for comparison, both a 1.5-tesla and a 3.0-tesla system. The thalamic Vim was clearly and consistently delineated on the 3-tesla images. These images were successfully used for target localization in essential tremor patients. In the volunteers data, images acquired using the 1.5-tesla system were inferior to those acquired using the 3-tesla system, lacking the ability to consistently provide reliably defined borders of the Vim. 3-Tesla MRI can provide high-quality depiction of the Vim, potentially enabling accurate treatment planning by direct visualization and definition of the targeted Vim.