Neurology Resident NC State University Raleigh, CA, United States
Abstract:
Background: Stainless steel cortical screws (CS) are commonly used in veterinary spinal stabilization procedures with computed tomography (CT) used post-operatively to evaluate implant placement. Hypothesis/
Objectives: This study evaluated the impact of metallic artifact on CT measurements of CS using an in vitro model.
Methods: Eighteen screws (6 each of 2.0 mm, 2.7 mm and 3.5 mm) were placed in ballistic gel and the construct underwent a CT scan. For each screw, Three blinded reviewers measured maximum screw width using a bone window (W 2000, L 500) while a non-blinded reviewer performed the same measurements using an ultrawide window (W 20,000, L 3000). The difference between measured and actual screw size (mean gross difference) was compared between screw sizes and window level.
Results: The mean gross difference across all screw sizes ranged from 1.291 to 2.788 mm with a percentage overestimation of 64.6 to 82.5%. The largest mean gross difference was seen in 3.5 mm screws. A positive correlation was found between implant size and gross difference (p < 0.001). The mean gross difference using the bone window was significantly larger than the ultrawide window for 2.7 mm (p = 0.059) and 3.5 mm (p = 0.011) screws.
Conclusions: Metallic artifact affects CT measurements of CS, with greater overestimation in bone window when compared to ultrawide window. These findings suggest that using an ultrawide window may improve measurement of screws in challenging clinical cases.
