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Corresponding author:John M. Rhee, Department of Orthopedic Surgery, Emory Spine Center, Emory University, 59 Executive Park South, Atlanta, GA 30327, USA. Email: jmrhee@emory.edu

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: John M. Rhee earns royalties from Biomet Zimmer Spine and Lippincott, is a consultant for Biomet Zimmer Spine, is a speaker for Depuy Spine, is a board member of the Cervical Spine Research Society, and holds stock in Phygen/Alphatec.

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The author(s) received no financial support for the research, authorship, and/or publication of this article.

Keywords:

  • foraminal stenosis
  • cervical spine
  • diagnostic study
  • 3-dimensional CT

Assessing Foraminal Stenosis in the Cervical Spine: A Comparison of Three-Dimensional Computed Tomographic Surface Reconstruction to Two-Dimensional Modalities

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Journal Title:

Global Spine Journal

Volume:

Volume 7, Number 3

Publisher:

, Pages 266-271

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Article | Final Publisher PDF

Abstract:

Study Design: Retrospective radiographic study. Objective: The optimal radiographic modality for assessing cervical foraminal stenosis is unclear. Determination on conventional axial cuts is made difficult due in part to the complex, oblique orientation of the cervical neuroforamen. The utility of 3-dimensonal (3D) computed tomography (CT) reconstruction in improving neuroforaminal assessment is not well understood. The objective of this study is to determine inter-rater variability in grading cervical foraminal stenosis using 3 different CT imaging modalities: 3D CT surface reconstructions (3DSR), 2D sagittal oblique multiplanar reformations (2D-SOMPR), and conventional 2D axial CT imaging. Methods: Pretreatment CT scans of 25 patients undergoing surgery for cervical spondylotic radiculopathy were analyzed at 2 levels: C5-C6 and C6-C7. Simple interrater agreement and kappa-Fleiss coefficients were calculated for each imaging modality and stenosis grade. Image reviewers (attending spine surgeon, attending neuroradiologist, spine fellow) interpreted each CT scan in 3 different formats: axial, 2D-SOMPR, and 3DSR. Four cervical foramina at 2 spinal levels were graded as normal (no stenosis), mild (≤25% stenosis), moderate (25%-50% stenosis), or severe (>50% stenosis). Results: Across all imaging modalities, interrater reliability was fair when grading foraminal stenosis (κ < 0.4). Agreement was lowest for the axial images (κ = 0.119) and highest for the 3D CT reconstructions (κ = 0.334). 2D-SOMPR images also led to improved interrater reliability when compared with axial images (κ = 0.255). Conclusion: Grading cervical foraminal stenosis using conventional axial CT imaging is difficult with low interrater reliability. CT modalities that provide a circumferential view of the cervical foramen, such as 2D-SOMPR and 3D CT reconstruction, had higher rates of interobserver reliability in grading foraminal stenosis than conventional axial cuts, with 3D having the highest. As these 3D reconstructions can be obtained at no additional cost or radiation exposure over a conventional CT scan, and because they can provide useful information in determining levels being considered for surgical decompression, we recommend they be utilized when evaluating cervical foramina.

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Copyright © The Author(s) 2017

This is an Open Access work distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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