• Open Access

Optic radiation tractography and vision in anterior temporal lobe resection

Authors

  • Gavin P. Winston MA, BM, BCh,

    Corresponding author
    1. Epilepsy Society Magnetic Resonance Imaging Unit, Department of Clinical and Experimental Epilepsy, University College London Institute of Neurology, London, United Kingdom
    • UCL Institute of Neurology (Box 29), Queen Square, London, WC1N 3BG, United Kingdom
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  • Pankaj Daga MSc,

    1. University College London Centre for Medical Image Computing, London, United Kingdom
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  • Jason Stretton BSc,

    1. Epilepsy Society Magnetic Resonance Imaging Unit, Department of Clinical and Experimental Epilepsy, University College London Institute of Neurology, London, United Kingdom
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  • Marc Modat MSc,

    1. University College London Centre for Medical Image Computing, London, United Kingdom
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  • Mark R. Symms PhD,

    1. Epilepsy Society Magnetic Resonance Imaging Unit, Department of Clinical and Experimental Epilepsy, University College London Institute of Neurology, London, United Kingdom
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  • Andrew W. McEvoy MB, BS,

    1. Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, London, United Kingdom
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  • Sebastien Ourselin PhD,

    1. University College London Centre for Medical Image Computing, London, United Kingdom
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  • John S. Duncan DM, FRCP

    1. Epilepsy Society Magnetic Resonance Imaging Unit, Department of Clinical and Experimental Epilepsy, University College London Institute of Neurology, London, United Kingdom
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Abstract

Objective:

Anterior temporal lobe resection (ATLR) is an effective treatment for refractory temporal lobe epilepsy but may result in a contralateral superior visual field deficit (VFD) that precludes driving in the seizure-free patient. Diffusion tensor imaging (DTI) tractography can delineate the optic radiation preoperatively and stratify risk. It would be advantageous to incorporate display of tracts into interventional magnetic resonance imaging (MRI) to guide surgery.

Methods:

We studied 20 patients undergoing ATLR. Structural MRI scans, DTI, and visual fields were acquired before and 3 to 12 months following surgery. Tractography of the optic radiation was performed on preoperative images and propagated onto postoperative images. The anteroposterior extent of the damage to Meyer's loop was determined, and visual loss was quantified using Goldmann perimetry.

Results:

Twelve patients (60%) suffered a VFD (10–92% of upper quadrant; median, 39%). Image registration took <3 minutes and predicted that Meyer's loop was 4.4 to 18.7mm anterior to the resection margin in these patients, but 0.0 to 17.6mm behind the resection margin in the 8 patients without VFD. The extent of damage to Meyer's loop significantly correlated with the degree of VFD and explained 65% of the variance in this measure.

Interpretation:

The optic radiation can be accurately delineated by tractography and propagated onto postoperative images. The technique is fast enough to propagate accurate preoperative tractography onto intraoperative scans acquired during neurosurgery, with the potential to reduce the risk of VFD. ANN NEUROL 2012;

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