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Mundy, Claire

University of British Columbia

Degenerative Lumbar Spondylolisthesis (DLS) is a frequently diagnosed spine pathology, presenting as an anterior displacement of one vertebra over the subjacent one, and can require surgical treatment. One of the important factors in determining surgical treatment for DLS patients is clinical spinal instability. Unfortunately, clinical spinal instability is not well understood and current clinical methods for evaluating it are considered rather limited as they do not account for vertebral motion in six Degrees of Freedom (DOF). As a result, determining the most appropriate surgical intervention can be challenging. Our research goal is therefore to develop a more accurate method for measuring clinical spinal instability in six DOF, with the overall goal of improving surgical management of DLS patients. In this thesis, we developed and implemented a vertebral 2D/3D registration procedure, which spatially aligns a patient’s preoperative CT to two biplanar X-ray images, to measure intervertebral motion at the level of spondylolisthesis. Our intensity-based registration method uses X-ray images captured using an EOS System, a relatively new clinical biplanar scanner that provides significantly less radiation to subjects compared to conventional X-ray systems. We validated our registration approach with phantom models and found that our process has accuracies ranging between 0.12 to 0.67 mm for translations and -0.02 to 0.74 deg for rotations, which is below the magnitude at which instability may be occurring. We also found that our process is repeatable with sub-millimetre (0.06 to 0.70 mm) and sub-degree (0.01 to 0.51 deg) variability. We compared the micro and normal radiation dose settings of the EOS System, and the results indicate that the microdose and normal dose settings are equivalent (within the bounds of +/- 0.5 mm and +/- 0.5 deg) for most position parameters. In preparation for evaluating our system with clinical data, we have designed a clinical pilot study and have received the necessary hospital approvals to move the project forward. Overall, the EOS biplanar X-ray registration approach presented here appears to have sufficient accuracy and repeatability to be useful in investigating intervertebral motion patterns in DLS patients.

Text

2021-11-25

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/80261

Biomedical Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/