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-tonoise 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.