Target Identification for Stereotactic Thalamotomy Using Diffusion Tractography

Kincses, Zsigmond Tamás; Szabó, Nikoletta; Valálik, István; Kopniczky, Zsolt; Dézsi, Lívia; Klivényi, Péter; Jenkinson, Mark; Király, András; Babos, Magor; Vörös, Erika; Barzó, Pál; Vécsei, László

doi:10.1371/journal.pone.0029969

Cited by 30 publications

(43 citation statements)

References 39 publications

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“…However, current magnetic resonance imaging (MRI) sequences (both 1.5 and 3 Tesla) fail to visualize the VIM, and conventional surgical targeting relies on a combination of indirect targeting methods and microelectrode recordings (MER) . The indirect targeting methods do not take into account the variability in the location of VIM . This may result in heterogeneous and suboptimal outcomes with tremor surgery .…”

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confidence: 99%

Tractography‐Based Ventral Intermediate Nucleus Targeting: Novel Methodology and Intraoperative Validation

et al. 2016

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Backgro und: The ventral intermediate nucleus of the thalamus is not readily visible on structural magnetic resonance imaging. Therefore, a method for its visualization for stereotactic targeting is desirable. Objective: The objective of this study was to define a tractography-based methodology for the stereotactic targeting of the ventral intermediate nucleus. Methods:The lateral and posterior borders of the ventral intermediate nucleus were defined by tracking the pyramidal tract and medial lemniscus, respectively. A thalamic seed was then created 3 mm medial and anterior to these borders, and its structural connections were analyzed. The application of this method was assessed in an imaging cohort of 14 tremor patients and 15 healthy controls, in which we compared the tractography-based targeting to conventional targeting. In a separate surgical cohort (3 tremor and 3 tremor-dominant Parkinson's disease patients), we analyzed the accuracy of this method by correlating it with intraoperative neurophysiology.

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confidence: 99%

Tractography‐Based Ventral Intermediate Nucleus Targeting: Novel Methodology and Intraoperative Validation

et al. 2016

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“…White matter tractography based on diffusion tensor imaging (DTI) has been proposed as a tool to assist localization of targets based on their white matter connectivity and has been applied to the Vim, to identify cerebellar input to the Vim (dentate-rubro-thalamic tract) with improved clinical outcomes. 9,13,17,25,26,29 Low-intensity focused ultrasound has also been proposed as a method to assist intraoperative targeting. 24 These low-intensity focused ultrasound sonications, which create no histological damage and have no MR thermometry heat signature (i.e., do not cause heating), are able to stimulate neural tissue and generate somatosensory evoked potentials when targeting the ventral posterolateral nucleus in an animal model.…”

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confidence: 99%

Volumetric analysis of magnetic resonance–guided focused ultrasound thalamotomy lesions

Harary¹,

Essayed²,

Valdés³

et al. 2018

Neurosurgical Focus

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OBJECTIVEMagnetic resonance–guided focused ultrasound (MRgFUS) thalamotomy was recently approved for use in the treatment of medication-refractory essential tremor (ET). Previous work has described lesion appearance and volume on MRI up to 6 months after treatment. Here, the authors report on the volumetric segmentation of the thalamotomy lesion and associated edema in the immediate postoperative period and 1 year following treatment, and relate these radiographic characteristics with clinical outcome.METHODSSeven patients with medication-refractory ET underwent MRgFUS thalamotomy at Brigham and Women’s Hospital and were monitored clinically for 1 year posttreatment. Treatment effect was measured using the Clinical Rating Scale for Tremor (CRST). MRI was performed immediately postoperatively, 24 hours posttreatment, and at 1 year. Lesion location and the volumes of the necrotic core (zone I) and surrounding edema (cytotoxic, zone II; vasogenic, zone III) were measured on thin-slice T2-weighted images using Slicer 3D software.RESULTSPatients had significant improvement in overall CRST scores (baseline 51.4 ± 10.8 to 24.9 ± 11.0 at 1 year, p = 0.001). The most common adverse events (AEs) in the 1-month posttreatment period were transient gait disturbance (6 patients) and paresthesia (3 patients). The center of zone I immediately posttreatment was 5.61 ± 0.9 mm anterior to the posterior commissure, 14.6 ± 0.8 mm lateral to midline, and 11.0 ± 0.5 mm lateral to the border of the third ventricle on the anterior commissure–posterior commissure plane. Zone I, II, and III volumes immediately posttreatment were 0.01 ± 0.01, 0.05 ± 0.02, and 0.33 ± 0.21 cm3, respectively. These volumes increased significantly over the first 24 hours following surgery. The edema did not spread evenly, with more notable expansion in the superoinferior and lateral directions. The spread of edema inferiorly was associated with the incidence of gait disturbance. At 1 year, the remaining lesion location and size were comparable to those of zone I immediately posttreatment. Zone volumes were not associated with clinical efficacy in a statistically significant way.CONCLUSIONSMRgFUS thalamotomy demonstrates sustained clinical efficacy at 1 year for the treatment of medication-refractory ET. This technology can create accurate, predictable, and small-volume lesions that are stable over time. Instances of AEs are transient and are associated with the pattern of perilesional edema expansion. Additional analysis of a larger MRgFUS thalamotomy cohort could provide more information to maximize clinical effect and reduce the rate of long-lasting AEs.

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“…Probabilistic tractography can be used to establish the connectivity profile of major thalamic target nuclei (and particularly the Vim nucleus) prior to functional neurosurgery [24,25,33]. Although the Vim nucleus can be identified with this technique, the extensive postacquisition data processing is not currently compatible with routine SRS planning software, and these techniques have yet to be validated in the clinic.…”

Section: Discussionmentioning

confidence: 99%

Prelemniscal Radiations: A New Reliable Landmark of the Thalamic Nucleus Ventralis Intermedius Location?

Lefranc

Carron²,

Régis³

2015

Stereotact Funct Neurosurg

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Background: The thalamic nucleus ventralis intermedius (Vim nucleus) is the main surgical target for the management of intractable tremor. The Vim nucleus cannot be reliably located with routine stereotactic imaging, and so targeting relies on indirect coordinates. Objective: We propose to investigate if colored fractional anisotropy (FA) mapping can help to locate the Vim nucleus by identifying its borders, particularly the prelemniscal radiations (Raprl) that lie below and behind the nucleus. Method: We retrospectively reviewed the colored FA maps for 18 consecutive patients having undergone gamma knife stereotactic Vim thalamotomy for disabling tremor. Results: The Raprl were easily located on colored FA maps and enabled the identification of the lower and posterior borders of the Vim nucleus in all patients. In the medial plane, the mean distance ± SD between the Raprl and Vim nucleus was 0.77 ± 1.19 mm (range: 0.1-3.3). The Raprl were located 1.35 ± 1.33 mm (range: 0.2-3.9) behind the Vim nucleus and 1.99 ± 1.23 mm (range: 0.7-4.4) below it. The mean vector distance ± SD between the Vim nucleus and the Raprl was 3 ± 1.38 mm (range: 1.25-5.2). Conclusion: The Raprl can be easily seen on colored FA maps and constitute a reliable landmark for the borders of the Vim nucleus.

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Target Identification for Stereotactic Thalamotomy Using Diffusion Tractography

Cited by 30 publications

References 39 publications

Tractography‐Based Ventral Intermediate Nucleus Targeting: Novel Methodology and Intraoperative Validation

Tractography‐Based Ventral Intermediate Nucleus Targeting: Novel Methodology and Intraoperative Validation

Volumetric analysis of magnetic resonance–guided focused ultrasound thalamotomy lesions

Prelemniscal Radiations: A New Reliable Landmark of the Thalamic Nucleus Ventralis Intermedius Location?

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