Edge-enhancing gradient echo with multi-image co-registration and averaging (EDGE-MICRA) for targeting thalamic centromedian and parafascicular nuclei

Abstract

Background and purpose Deep brain stimulation of the thalamus is an effective treatment for multiple neurological disorders. The centromedian and parafascicular nuclei are recently emerging targets for multiple conditions, such as epilepsy and Tourette syndrome; however, their limited visibility on conventional magnetic resonance imaging sequences has been a major obstacle. The goal of this study was to demonstrate the feasibility of a high-resolution and high-contrast targeting sequence for centromedian-parafascicular deep brain stimulation using a recently described magnetic resonance imaging sequence, three-dimensional edge-enhancing gradient echo. Methods The three-dimensional edge-enhancing gradient echo sequence was performed on a normal volunteer for a total of six acquisitions. Multi-image co-registration and averaging was performed by first co-registering each of the six scans and then averaging to produce an edge-enhancing gradient echo-multi-image co-registration and averaging scan. The averaging was also performed for two, three, four and five scans to assess the change in the signal-to-noise ratio and identify the ideal balance of image quality and scan time. Results The edge-enhancing gradient echo-multi-image co-registration and averaging scan allowed clear boundary delineation of the centromedian and parafascicular nuclei. The signal-to-noise ratio increased as a function of increasing scan number, but the added gain was small beyond four scans for the imaging parameters used in this study. Conclusions The recently described three-dimensional edge-enhancing gradient echo sequence provides an easily implementable approach, using widely available magnetic resonance imaging technology without complex post-processing techniques, to delineate centromedian and parafascicular nuclei for deep brain stimulation targeting.

Centromedian thalamic neuromodulation for the treatment of idiopathic generalized epilepsy

“…Accordingly, studies have attempted to define both optimal targeting techniques as well as success based on active contact location ( Velasco M. et al, 2000 ; Velasco et al, 2007 ; Ilyas et al, 2022 ). Newer imaging modalities and improved MRI sequences may provide better delineation of the CM and allow for direct targeting in future studies ( Warren et al, 2020 ; Middlebrooks et al, 2021 ).…”

DiMANI: diffusion MRI for anatomical nuclei imaging—Application for the direct visualization of thalamic subnuclei

“…This has led surgical teams to use templates and atlases, which do not account for inter-individual anatomic variability, and are oftentimes derived from individuals outside of the patient's population demographics (e.g., age, disease state). Several groups have worked to develop new imaging methods for direct visualization, including susceptibility weighted imaging (SWI) (Abosch et al, 2010 ; Najdenovska et al, 2019 ), quantitative magnetic susceptibility mapping (QSM) (Deistung et al, 2013 ; Chiang et al, 2018 ), or white-matter nulled T1 imaging, such as FGATIR (Sudhyadhom et al, 2009 ; Hoch and Shepherd, 2022 ), 3D-EDGE (Middlebrooks et al, 2021 ), and WMn-MPRAGE (Su et al, 2019 ). However, these methods have drawbacks.…”

Synthetic Inversion Image Generation using MP2RAGE T1 Mapping for Surgical Targeting in Deep Brain Stimulation and Lesioning

“…More recently, various sequence modifications have been proposed to improve the identification of these key targets and have become widely accepted standards for targeting approaches. By applying various inversion times (TI) to a traditional high-resolution, 3D T1-weighted gradient echo sequence (e.g., MPRAGE), several valuable contrasts can be obtained, such as white matter nulled (Fast Gray Matter Acquisition T1 Inversion Recovery [FGATIR]), gray matter nulled, and Edge-Enhancing Gradient Echo (EDGE) [6][7][8]. For example, FGATIR can accurately delineate the prelemniscal radiations/dentato-rubro-thalamic tract in DBS for tremor and the anterior nucleus and mammillothalamic tract in epilepsy DBS [9][10][11].…”

“…For example, FGATIR can accurately delineate the prelemniscal radiations/dentato-rubro-thalamic tract in DBS for tremor and the anterior nucleus and mammillothalamic tract in epilepsy DBS [9][10][11]. EDGE has been shown to delineate the CM and parafascicular nuclei [8]. Unfortunately, acquiring multiple sequences individually can be a time-consuming process, and prescribing different sets of sequences for each surgical indication is a complex process that may lead to errors in acquiring the correct images.…”