Visualization of Neural Targets With 3T MRI

Overview

Functional neurosurgery is dedicated to modulating aberrant neural circuits associated with a wide range of neurological conditions. Recently, technological advances in MRI have permitted marked improvements in the direct visualization of neural targets, which is necessary for the accurate targeting in functional neurosurgery procedures. This research study focuses on imaging patient brains before their scheduled procedures by using a 3 tesla (T) MRI to provide higher resolution and quality brain images. The reason for this study is to assess the image quality using different MRI sequences or settings to improve the image resolution of the most common functional neurosurgery targets (e.g., subthalamic nucleus, globus pallidus, and thalamus) and compare the image quality of the brains in patients with healthy controls. Performing a preoperative MRI is standard-of-care for patients indicated for deep brain stimulation (DBS), gamma knife radiosurgery (GKRS), radiofrequency ablation (RFA), magnetic resonance-guided focused ultrasound (MRgFUS). MRI sequence parameters shown to improve the image quality of different neural structures in a recent literature review (Boutet et al. 2021) will be reproduced on the 3T MRI at Toronto Western Hospital.

This is an exploratory prospective experimental study that will assess the ability of different MRI sequences to visualize common functional neurosurgical targets. Some neural structures (i.e., STN) are sometimes not visualized as well, particularly in older patients, when compared to healthy controls. The findings from this study should help in identifying the advanced sequences for direct visualization of these targets, that could then be used for improved preoperative planning of functional neurosurgical procedures. Several advanced MRI sequences will be conducted when imaging patients or healthy participant. All advanced sequences have previously been published in the literature as viable, safe preoperative planning sequences for functional neurosurgical treatments at other centres. All MRI scans in this study will be acquired at the Toronto Western Hospital (TWH). For example, structural scans using sequences that can null or not receive signals from fluids in the brain and reduce geometric distortion (i.e., fluid attenuated inversion recovery (FLAIR)), null white matter signals (i.e., fast gray matter acquisition T1 inversion recovery (FGATIR)), and enhance the visualization of iron concentrated neural structures (i.e., quantitative susceptibility mapping (QSM)) will be performed. These advanced sequences will be compared to conventional structural MRI sequences (i.e., T1-weighted (T1W) or T2-weighted (T2W)) that are typically used for anatomical purposes and direct visualization of neural structures. Ultimately, results from this study should enhance quality of care, clinical benefits, and data quality.