Three Dimensional Artifact Free Visualization of Different Metallic Intervertebral Disc Spacers With Flat Panel Detector Volume CT (FD-VCT): A Comparative Cadaveric Spine Study
Prof. Dr. Thorsten Ernstberger, Christian Dullin, Gottfried Buchhorn, Gabert Heidrich

Abstract
Image quality and implant detectability by conventional imaging methods are suboptimal for perioperative spinal diagnostics, primarily limited by implant-related artifacts. This preclinical experimental study aimed to evaluate the imaging quality of two different metallic intervertebral spacers used as stand alone cages examined by flat-panel detector-based volumetric computed tomography (FD-VCT) versus MRI. Both spacer types (titanium, cobalt-chrome-molybdenum) were implanted in a porcine cadaver spine and then examined by MRI using T1-weighted turbo spin echo sequences. Comparative imaging was performed with an experimentally approved FD-VCT prototype featuring 2D and 3D imaging and high isotropic spatial resolution. Data analysis focused on spacer shape, implant positioning and implant-bone interface. Compared to MRI, image quality and detectability of all target characteristics were better with FD-VCT and without the usual artifacts. Using its option for implant-specific imaging, the experimental FD-VCT imager allowed reliable determination of additional data such as dimension and volume. These experiments provide initial evidence that FD-VCT produces an excellently artifact-free imaging considering distinguishing key characteristics of intervertebral implants. Thus, FD-VCT appears to be the ideal modality in preclinical studies for evaluation of osseous integration processes secondary to interbody spondylodesis.

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