Direct visualization of anatomic subfields within the superior aspect of the human lateral thalamus by MRI at 7T.
The morphology of the human thalamus shows high interindividual variability.  Therefore, direct visualization of landmarks within the thalamus is essential for an improved definition of electrode positions for deep brain stimulation.  The aim of this study was to provide anatomic detail in the thalamus by using inversion recovery TSE imaging at 7T. The MR imaging protocol was optimized on 1 healthy subject to segment thalamic nuclei from one another.  Final images, acquired with 0.5(2)-mm2 in-plane resolution and 3-mm section thickness, were compared with stereotactic brain atlases to assign visualized details to known anatomy.  The robustness of the visualization of thalamic nuclei was assessed with 4 healthy subjects at lower image resolution.  Thalamic subfields were successfully delineated in the dorsal aspect of the lateral thalamus.  T1-weighting was essential.  MR images had an appearance very similar to that of myelin-stained sections seen in brain atlases.  Visualized intrathalamic structures were, among others, the lamella medialis, the external medullary lamina, the reticulatum thalami, the nucleus centre médian, the boundary between the nuclei dorso-oralis internus and externus, and the boundary between the nuclei dorso-oralis internus and zentrolateralis intermedius internus.  Inversion recovery-prepared TSE imaging at 7T has a high potential to reveal fine anatomic detail in the thalamus, which may be helpful in enhancing the planning of stereotactic neurosurgery in the future.