Perioperative Structural Magnetic Resonance Imaging in Neurosurgery

• Author / Creator

  Elliott, Cameron Alistair

• Magnetic resonance imaging (MRI) is a universally-used tool in clinical neurosurgery. It has revolutionized preoperative diagnosis, surgical planning, intraoperative targeting, and postoperative surveillance. Nevertheless, the idea that early, quantifiable perioperative structural changes of the brain relate meaningfully to the prediction of long-term structural consequences and functional outcomes remains underdeveloped.
  The central hypothesis of this thesis is that the perioperative period provides a unique opportunity to examine brain structure using MRI, which may predict eventual clinical outcomes. The specific aims of this thesis were to determine (1) the predictive value of early, post-injury, perioperative clinical diffusion-weighted imaging (DWI) in the setting of pediatric traumatic brain injury (TBI) and suspected non-accidental trauma (NAT) to predict ultimate distribution of structural brain damage and functional outcome; (2) the relationship between structural characteristics of various components of the limbic system, measured using perioperative MRI, and seizure control or neuropsychological outcomes in patients with drug-resistant temporal lobe epilepsy (TLE); and (3) the feasibility of acquiring diffusion tensor imaging (DTI) intraoperatively, with an open cranium, during surgery for intraaxial brain lesions using a novel, readout-segmented DTI approach.
  In study #1, we demonstrate that the pattern of restricted diffusion on early post-injury diffusion-weighted MRI is predictive of long-term structural volume loss and corresponding clinical functional deficits in pediatric TBI due to suspected NAT. In study #2, we characterize the macrostructural and microstructural changes of limbic structures following resective surgery for drug-resistant TLE using a within-subjects longitudinal design with special focus on the early postoperative period. This work identified a novel structural biomarker of refractory postoperative seizures—contralateral hippocampal volume loss—significant within one-week of surgery and found to be more pronounced amongst those with postoperative seizures. Postoperative hippocampal DTI changes suggest that the mechanism of contralateral hippocampal atrophy is multifactorial, involving resolution of cytotoxic edema and deafferentation but not early postoperative fluid shifts. In study #3, we demonstrate the utility of readout-segmented DTI (compared to conventional, single-shot DTI) for open cranial intraoperative white matter reconstructions of surgically relevant tracts during resective neurosurgery by reducing the impact of susceptibility artifact-related image degradation and spatial distortion. Taken together, the studies presented in this thesis establish that structural brain changes can indeed be measured in the perioperative period and do relate meaningfully to patient outcome.

• Subjects / Keywords

  • Temporal Lobe Epilepsy Surgery
  • Diffusion Tensor Imaging
  • Magnetic Resonance Imaging
  • Hippocampal Volumetry

• Graduation date

  Fall 2018

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3S46HN9Q

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.