Imaging for deep brain stimulation: The zona incerta at 7 Tesla.

AIM

To evaluate different promising magnetic resonance imaging (MRI) methods at 7.0 Tesla (T) for the pre-stereotactic visualization of the zona incerta (ZI).

METHODS

Two neuroradiologists qualitatively and quantitatively examined T2-turbo spin-echo (T2-TSE), T1-weighted gradient-echo, as well as FLASH2D-T2Star and susceptibility-weighted imaging (SWI) for the visualization of the ZI at 7.0 T MRI. Delineation and image quality for the ZI were independently examined using a 6-scale grading system. Inter-rater reliability using Cohen's kappa coefficient (κ) were assessed. Contrast-to-noise ratios (CNR), and signal-to-noise ratios (SNR) for the ZI were calculated for all sequences. Differences in delineation, SNR, and CNR between the sequences were statistically assessed using a paired t-test. For the anatomic validation the coronal FLASH2D-T2Star images were co-registered with a stereotactic atlas (Schaltenbrand-Wahren).

RESULTS

The rostral part of the ZI (rZI) could easily be identified and was best and reliably visualized in the coronal FLASH2D-T2Star images. The caudal part was not definable in any of the sequences. No major artifacts in the rZI were observed in any of the scans. FLASH2D-T2Star and SWI imaging offered significant higher CNR values for the rZI compared to T2-TSE images (P > 0.05). The co-registration of the coronal FLASH2D-T2Star images with the stereotactic atlas schema (Schaltenbrand-Wahren) confirmed the correct localization of the ZI in all cases.

CONCLUSION

FLASH2D-T2Star imaging (particularly coronal view) provides the reliable and currently optimal visualization of the rZI at 7.0 T. These results can facilitate a better and more precise targeting of the caudal part of the ZI than ever before.