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. 2010 Mar;2(1):8-12.
doi: 10.4055/cios.2010.2.1.8. Epub 2010 Feb 4.

Inter- and intra-observer variability of a cervical OPLL classification using reconstructed CT images

Han Chang  1 , Chae-Gwan Kong, Ho-Yeon Won, Ju-Hwan Kim, Jong-Beom Park
Affiliations

Inter- and intra-observer variability of a cervical OPLL classification using reconstructed CT images

Han Chang et al. Clin Orthop Surg. 2010 Mar.

Abstract

Background: The lateral radiograph-based system described by Tsuyama is used widely to classify ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. However, OPLL is a complex 3-dimensional (3-D) lesion, not a simple and uniplanar one, which is often difficult to identify on a lateral radiograph. Furthermore, its reliability among spine surgeons has not been investigated. Given the popularity of a reconstructed computed tomography (CT), this study examined the inter- and intra-observer reliability of lateral radiograph-based OPLL classification using that modality.

Methods: Five spine surgeons independently reviewed the lateral radiograph, axial CT, 2-D (sagittal) and 3-D reconstructed CT images of 108 OPLL patients on 2 separate occasions. Based on these images, the reviewers classified each OPLL case according to the Tsuyama's system. The kappa values were used to assess the statistical reliability.

Results: The inter- and intra-observer kappa values were only 0.51 and 0.67 for the lateral radiograph, even in combination with the axial CT images, 0.70 and 0.85 for 2-D CT images, and 0.76 and 0.86 for 3-D CT images, respectively. These kappa values showed a good-to-excellent range for the 2-D and 3-D reconstructed CT images while those of the lateral radiograph indicated a fair range. According to the OPLL types, the inter- and intra-observer reliability was low in the continuous type and high in the circumscribed type on the lateral radiograph. However, the low reliability of the continuous type on lateral radiograph was overcome somewhat using 2-D and 3-D reconstructed CT images.

Conclusions: The inter- and intra-observer kappa values were only 0.51 and 0.67 for the lateral radiograph, even in combination with the axial CT images, 0.70 and 0.85 for 2-D CT images, and 0.76 and 0.86 for 3-D CT images, respectively. These kappa values showed a good-to-excellent range for the 2-D and 3-D reconstructed CT images while those of the lateral radiograph indicated a fair range. According to the OPLL types, the inter- and intra-observer reliability was low in the continuous type and high in the circumscribed type on the lateral radiograph. However, the low reliability of the continuous type on lateral radiograph was overcome somewhat using 2-D and 3-D reconstructed CT images.

Keywords: Classification; Computed tomography; Ossification of the posterior longitudinal ligament; Reliability.

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Figures

Fig. 1
Fig. 1
Sixty-one-yr-old male patient presented with the typical clinical symptoms of cervical myelopathy due to ossification of the posterior longitudinal ligament (OPLL). Most reviewers classified this case into the continuous type OPLL extending C1 to C7 using the lateral radiograph in combination with the axial CT images (A). However, the 2-dimensional (2-D) and 3-D CT reconstructed images showed an interrupted OPLL at the C4-C5 disc level (arrow) (B). Most of the reviewers re-classified this case into the mixed type OPLL extending C1 to C7 using the reconstructed CT images.
See this image and copyright information in PMC

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