Predicting Post-Operative Side Effects in VIM MRgFUS Based on THalamus Optimized Multi Atlas Segmentation (THOMAS) on White-Matter-Nulled MRI: A Retrospective Study - PubMed (original) (raw)
Predicting Post-Operative Side Effects in VIM MRgFUS Based on THalamus Optimized Multi Atlas Segmentation (THOMAS) on White-Matter-Nulled MRI: A Retrospective Study
Sonoko Oshima et al. AJNR Am J Neuroradiol. 2025.
Abstract
Background and purpose: Precise and individualized targeting of the ventral intermediate thalamic nucleus for the MR-guided focused ultrasound is crucial for enhancing treatment efficacy and avoiding undesirable side effects. In this study, we tested the hypothesis that the spatial relationships between Thalamus Optimized Multi Atlas Segmentation derived segmentations and the post-focused ultrasound lesion can predict post-operative side effects in patients treated with MR-guided focused ultrasound.
Materials and methods: We retrospectively analyzed 30 patients (essential tremor, n = 26; tremor-dominant Parkinson's disease, n = 4) who underwent unilateral ventral intermediate thalamic nucleus focused ultrasound treatment. We created ROIs of coordinate-based indirect treatment target, focused ultrasound-induced lesion, and thalamus and ventral intermediate thalamic nucleus segmentations. We extracted imaging features including 1) focused ultrasound-induced lesion volumes, 2) overlap between lesions and thalamus and ventral intermediate thalamic nucleus segmentations, 3) distance between lesions and ventral intermediate thalamic nucleus segmentation and 4) distance between lesions and the indirect standard target. These imaging features were compared between patients with and without post-operative gait/balance side effects using Wilcoxon rank-sum test. Multivariate prediction models of side effects based on the imaging features were evaluated using the receiver operating characteristic analyses.
Results: Patients with self-reported gait/balance side effects had a significantly larger extent of focused ultrasound-induced edema, a smaller fraction of the lesion within the ventral intermediate thalamic nucleus segmentation, a larger fraction of the off-target lesion outside the thalamus segmentation, a more inferior centroid of the lesion from the ventral intermediate thalamic nucleus segmentation, and a larger distance between the centroid of the lesion and ventral intermediate thalamic nucleus segmentation (p < 0.05). Similar results were found for exam-based side effects. Multivariate regression models based on the imaging features achieved areas under the curve of 0.99 (95% CI: 0.88 to 1.00) and 0.96 (95% CI: 0.73 to 1.00) for predicting self-reported and exam-based side effects, respectively.
Conclusions: Thalamus Optimized Multi Atlas Segmentation-based patient-specific segmentation of the ventral intermediate thalamic nucleus can predict post-operative side effects, which has implications for aiding the direct targeting of MR-guided focused ultrasound and reducing side effects.
© 2025 by American Journal of Neuroradiology.
Figures
Graphical abstract
FIG 1.
Imaging feature extraction pipeline. ROIs of standard target, FUS lesions and THOMAS segmentations were registered to the population-specific template generated from pre-operative T1-w and FGATIR images. Spatial relationships of ROI centroids, overlap of FUS lesions with segmentations and lesion volume characteristics were assessed. MRgFUS, MR-guided focused ultrasound; FGATIR, Fast Gray Matter Acquisition T1 Inversion Recovery; THOMAS, THalamus Optimized Multi Atlas Segmentation; VIM, ventral intermediate nucleus; TH, thalamus; AP, anterior-posterior; RL, right-left, SI, superior-inferior; ROI, region of interest.
FIG 2.
Procedures to create standard target, FUS lesions and THOMAS segmentations of thalamus and VIM. A, Standard target ROIs were created from coordinates of the first sonication. B, FUS lesions were generated by subtracting the pre-operative T2-weighted image from the post-operative image and applying a thresholding method. C, The thalamus and VIM were segmented by applying THOMAS to pre-operative FGATIR images. The VIM here corresponds to the ventral part (inferior half) of the ventral lateral posterior nucleus in the Morel atlas. MRgFUS, MR-guided focused ultrasound; THOMAS, THalamus Optimized Multi Atlas Segmentation; VIM, ventral intermediate nucleus; FGATIR, Fast Gray Matter Acquisition T1 Inversion Recovery; ROI, region of interest.
FIG 3.
Example THOMAS segmentations (yellow line: thalamus; white line: VIM nucleus) and MRgFUS treated lesions (magenta: Zone A; cyan: Zone B) are shown in axial and coronal views. In the patient with side effects A, lesions extend farther out of the thalamus and segmented VIM, compared to the patient without side effects (B). FGATIR, Fast Gray Matter Acquisition T1 Inversion Recovery; MRgFUS, MR-guided focused ultrasound; THOMAS, Thalamus Optimized Multi Atlas Segmentation; VIM, ventral intermediate nucleus; ROI, region of interest.
FIG 4.
Probabilistic maps of Zone A in the population-specific template space. The spatial relationship between THOMAS-based thalamic nuclei segmentations, Zone A probabilistic maps, and standard targets are illustrated in different cohorts. The Zone A probabilistic map represents the voxel-wise percentage of FUS lesions across the subjects, and the standard target contour represents 75th percentile of standard coordinate ROI across the subjects. THOMAS, THalamus Optimized Multi Atlas Segmentation; FUS, focused ultrasound; VA, ventral anterior nucleus; VLa, ventral lateral anterior nucleus; VLP, ventral lateral posterior nucleus; VPL, ventral posterior lateral nucleus; VPLd, dorsal part of ventral posterior lateral nucleus; Pul, pulvinar nucleus; CM, centromedian nucleus; MD-Pf, mediodorsal-parafascicular nucleus; Hb, habenula; MGN, medial geniculate nucleus; ROI, region of interest.
FIG 5.
Results of imaging feature comparisons between patients with self-reported or physical exam-based gait/balance side effects and those without. In patients with side effects, Zone B shows less overlap with VIM segmentation and the off-target fraction of Zone B outside TH segmentation is greater (Graphs A–B and D–E). Graphs C and F show receiver operating characteristic curves of multivariate prediction models of side effects using imaging features. ET, essential tremor; PD, Parkinson’s disease; VIM, ventral intermediate nucleus; TH, thalamus; AUC, area under the curve.
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