Direct Targeting of the Anterior Nucleus of the Thalamus via 3 T Quantitative Susceptibility Mapping

Abstract

Objective: Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) is a potentially effective, minimally invasive, and reversible method for treating epilepsy. The goal of this study was to explore whether 3 T quantitative susceptibility mapping (QSM) could delineate the ANT from surrounding structures, which is important for the direct targeting of DBS surgery.Methods: We obtained 3 T QSM, T1-weighted (T1w), and T2-weighted (T2w) images from 11 patients with Parkinson’s disease or dystonia who received subthalamic nucleus (STN) or globus pallidus interna (GPi) DBS surgery in our center. The ANT and its surrounding white matter structures on QSM were compared with available atlases. The contrast-to-noise ratios (CNRs) of ANT relative to the external medullary lamina (eml) were compared across the three imaging modalities. Additionally, the morphology and location of the ANT were depicted in the anterior commissure (AC)-posterior commissure (PC)-based system.Results: ANT can be clearly distinguished from the surrounding white matter laminas and appeared hyperintense on QSM. The CNRs of the ANT-eml on QSM, T1w, and T2w images were 10.20 ± 4.23, 1.71 ± 1.03, and 1.35 ± 0.70, respectively. One-way analysis of variance (ANOVA) indicated significant differences in CNRs among QSM, T1w, and T2w imaging modalities [F(2) = 85.28, p < 0.0001]. In addition, both the morphology and location of the ANT were highly variable between patients in the AC–PC-based system.Conclusion: The potential utility of QSM for the visualization of ANTs in clinical imaging is promising and may be suitable for targeting the ANT for DBS to treat epilepsy.

Direct localization and delineation of human pedunculopontine nucleus based on a self‐supervised magnetic resonance image super‐resolution method

“…Due to the high sensitivity to iron and myelin content in the brain tissue, QSM can provide superior imaging contrast between paramagnetic iron‐rich deep brain GM and the surrounding diamagnetic WM structures (Dimov et al, 2018 ; Kerl et al, 2012 ; Sun et al, 2015 ). It has been shown to facilitate the depiction of iron‐rich DBS targeting nuclei and sub‐nuclei from the surrounding WM structures, for example, the subthalamic nucleus (Alkemade et al, 2017 ; Liu et al, 2013 ), globus pallidus internus (Wei, Zhang, et al, 2019 ), sub‐nuclei of the thalamus (Li et al, 2019 ; Yu, Li, et al, 2021 ; Yu, Ren, et al, 2021 ; Zhang et al, 2018 ), and the dentate nucleus of the cerebellum (He et al, 2017 ). A previous study using 7.0‐T MRI susceptibility‐weighted imaging of the non‐human primate brainstem indicated that PPN shows higher susceptibility than its adjacent WM structures, such as the SCP and the lemniscal system (Zitella et al, 2015 ).…”

QSM Throughout the Body

“…[6][7][8] To date, QSM has been performed overwhelmingly in the brain, 2,3,[9][10][11][12][13] and has seen increased adoption in a variety of brain research protocols to study iron, [14][15][16][17][18][19][20][21] myelin, [22][23][24][25] and calcification, 26,27 as well as in clinical protocols such as presurgical mapping of deep brain stimulation targets. [28][29][30][31][32] However, QSM has seen also increasing use throughout the body, which is the focus of this review.…”

“…Quantitative susceptibility mapping (QSM) 1–4 recovers local tissue susceptibility from the nonlocal fields generated by susceptibility sources in gradient echo (GRE) or balanced steady‐state free precession 5 MRI through 1) saving phase in data acquisition and 2) performing spatial deconvolution according to the dipole field model in magnetism physics 6–8 . To date, QSM has been performed overwhelmingly in the brain, 2,3,9–13 and has seen increased adoption in a variety of brain research protocols to study iron, 14–21 myelin, 22–25 and calcification, 26,27 as well as in clinical protocols such as presurgical mapping of deep brain stimulation targets 28–32 . However, QSM has seen also increasing use throughout the body, which is the focus of this review.…”