Susceptibility-enhanced 3-Tesla T1-weighted spoiled gradient echo of the midbrain nuclei for guidance of deep brain stimulation implantation

SURGICAL PLANNING FOR deep brain stimulation implantation procedures requires T1-weighted imaging (T1WI) for stereotactic navigation. Because the subthalamic nucleus, the main target for deep brain stimulation, and other midbrain nuclei cannot be visualized on the stereotactic guidance T1WI, additional T2-weighted imaging (T2WI) is generally obtained and registered to the T1WI for surgical targeting. Surgical planning based on the registration of the 2 data sets is subject to error resulting from inconsistent geometric distortions and any subject movement between the 2 scans. In this article, we propose a new method to produce susceptibility-enhanced, contrast-optimized T1-weighted 3-dimensional spoiled gradient recalled acquisition in steady state images with enhanced contrast for midbrain nuclei within the volumetric T1WI data set itself, eliminating the need for additional T2WI. The scan parameters of 3-dimensional spoiled gradient recalled acquisition in steady state are chosen in a way that T1WI can be obtained from conventional magnitude reconstruction and images with improved contrast between midbrain nuclei and surrounding tissues can be produced from the same data by performing susceptibility-weighted imaging reconstruction on a chosen region of interest. In addition, our preliminary experience suggests that the resulting contrast between the midbrain nuclei is superior to the current state-of-the-art fast spin echo T2WI in depicting the subthalamic nucleus as distinct from the substantia nigra pars reticulata and clear depiction of the nucleus ventrointermedius externus of thalamus.