Magnetic susceptibility is an important source of contrast in MRI, which arises from the subtle field perturbations generated by inter-molecular interaction in response to an external magnetic field. The DRT tract consists mainly of axon fibers covered by myelin sheaths that cause magnetic susceptibility variations. In addition, magnetic susceptibility of fiber bundle is in fact anisotropic. Such distinctive features of the DRT can generate a unique type of susceptibility contrast with respect to its neighboring thalamic tissues, yet clinically practical protocols are lacking. This study will utilize a novel MR susceptibility-based method, termed 'MR Susceptibility Imaging with Short Echo Time (MR-SISET)' which leverages short echo times to realize high contrast for direct and individualized DRT targeting. Combined with machine learning (ML) approaches, an automatic, operator-independent DRT-recognition will be achieved. This could provide a valid support to operators in the surgical planning and significantly improve the current operative methodology.~MR imaging will be done on a 3T MRI Magnet at the NYU Langone Health. All patients will undergo a routine clinical preoperative MRI of the brain under general anesthesia to reduce movement artifacts. The proposed sequence (<15 minutes) will be added as a supplementary sequence only for the preoperative imaging for subjects who agree to participate. The operator/clinician will be blinded to the results of this study for the MRgFUS treatment. A routine clinical postoperative MRI will be performed prior to discharge by the clinician, typically the following day of the MRgFUS treatment. The severity of tremor will be assessed before and after the treatment (~6 weeks). Postoperative clinical data will be retrieved to get a surgical target lesion and clinical outcome after treatment in order to confirm our method.
The purpose of this investigation is to determine the optimal DRT/VIM target location and its safety margins based on MR-SISET imaging features by comparing with postoperative lesions and clinical outcomes in patients with tremor who will undergo the MRgFUS tremor therapy.