connectivity-augmented surgical targeting: individualization of a 3d atlas of the human thalamus

Connectivity-augmented Surgical Targeting: Individualization of a Mean, 3D Atlas of the Human Thalamus

A. JAKAB1,3, R. BLANC1, A. MOREL2, E. BERENYI3, G. SZEKELY1

1. Computer Vision Laboratory, ETH, Zurich

2. Center for Clinical Research, University Hospital Zurich

3. Department of Biomedical Laboratory and Imaging Science, University of Debrecen

Mittwoch, 12. April 2023 2D-ITET / COMPUTER VISION LABORATORY

Transcranial MR-guided Focused Ultrasound Surgery

(1st Study on TcMRgFUS thalamotomy – Kinderspital, Zurich) Deep brain stimulation

New demands

Image-guided interventions in the thalamus

Higher precision of structural imaging,

intraprocedural

New information on internal structure

(nuclei) and function (connection)

Direct targeting, individual maps

State of the art imaging of the thalamus with DTI

Mittwoch, 12. April 2023 3D-ITET / COMPUTER VISION LABORATORY

Diffusion tensor imaging and probabilistic

tractography visualizes cortico-thalamic

connections

Top right images> Behrens et al. Non-

invasive mapping of connections

between human thalamus and cortex

using diffusion imaging Nature

Neuroscience 6, 750 - 757 (2003)

Clinical, 1.5T 3DT1

Gross, structural information

STUDY OBJECTIVES

(1) To develop a target map generation tool for image-guided neurosurgery

(2) Fit a 3D thalamus atlas to the patient’s geometry, refined by functional information (e.g. locations of specific cortico-thalamic connectivities)

(3) Assess the feasibility by observing ultrahigh-field MRI and postmortem MRI images with intrathalamic contrast

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Methods – data and image preparation

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A Krauth, R Blanc, A Poveda, D Jeanmonod, A Morel, G Székely (2010)A mean three-dimensional atlas of the human thalamus: Generation from multiple histological data. Neuroimage. 49(3). 2053-2062.

3D THALAMUS ATLAS – 7 thalami1. Healhy Controls (n=40)

2. 3DT1+DTI tractography

3. Use STATISTICAL SHAPE MODELS to deform the thalamus to patient space

4. How to deform the thalamus:

1. Outline, warping

2. Inside – match DTI points

5. Validation

1. Nuclei vs. tractography

2. Postmortem hi-res images(n=4)

Results – aligned maps and intrathalamic landmarks

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Black outlines: SSM-matched thalamus atlas Red spot: somatosensory connections, VPL

Results – Comparison to ACPC matching

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Blue: SSM-based target map

Red: ACPC aligned thalamus atlas

Comparison on 1.5 T clinical imaging and CORTICOTHALAMIC TRACTOGRAPHY

VL nucleus(VLa, VLpv)

Somatomotor connections

Somatomotor connections

Results – Comparison to ACPC matching

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Blue: SSM-based target map

Red: ACPC aligned thalamus atlas

Comparison on 7.0 T post mortem imagingCENTROMEDIAN NUCLEUS

Results – spatial accuracy (qualitative)

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Post-mortem high-res. MRI (protondensity-weighted)

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Name of the structure tested

Alignment method Mean distance (mm)

Median distance (mm)

Thalamus outline ACPC reg. with scaling 1.44 ± 0.44 1.24 ± 0.44

Thalamus outline Rigid reg. of surface 1.16 ± 0.11 1.07 ± 0.13

Thalamus outline SSM matching of outline

0.83 ± 0.1 0.56 ± 0.09

Thalamus outline Hybrid SSM matching (internal landmarks)

1.07 ± 0.18 0.83 ± 0.17

Postmortem nuclei (AV, MDmc, MDpc)

SSM matching of outline

0.79 ± 0.22 0.59 ± 0.14

Results – spatial accuracy (quantitative)

CONCLUSIONS(1) We aligned a 3D mean thalamus atlas to the patient’s geometry with feasible accuracy (< 1mm)

(2) Comparison with the conventional ACPC matching method shows superiority

(3) Nonlinear deformation of the thalamus makes the shape more individual = follows individual variability

(4) DTI corticothalamic tractography can be implemented in the method

(5) Such target maps can be used for image-guided neurosurgery

Mittwoch, 12. April 2023 11D-ITET / COMPUTER VISION LABORATORY

Thank you for your attention…

Acknowledgements:

Anne Morel – thalamus cyto work

Rémi Blanc – SSM programming

Klaas Pruesmann – 7T imaging lab