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

Area of Science:

• Orthopedic Surgery
• Radiology
• Spinal Imaging

Background:

• The Tsuyama system, based on lateral radiographs, is widely used for classifying cervical spine ossification of the posterior longitudinal ligament (OPLL).
• OPLL is a complex 3-dimensional lesion, posing challenges for accurate identification on standard lateral radiographs.
• The reliability of radiograph-based OPLL classification among spine surgeons has not been well-established.

Purpose of the Study:

• To evaluate the inter- and intra-observer reliability of the Tsuyama system for OPLL classification using lateral radiographs compared to reconstructed computed tomography (CT) imaging.
• To determine if CT-based imaging modalities improve the reliability of OPLL classification.

Main Methods:

• Five spine surgeons independently reviewed images from 108 OPLL patients on two separate occasions.
• Image modalities included lateral radiograph, axial CT, 2-D sagittal CT, and 3-D reconstructed CT.
• Kappa values were calculated to assess inter- and intra-observer reliability for OPLL classification using Tsuyama's system.

Main Results:

• Lateral radiographs yielded low inter- and intra-observer kappa values (0.51 and 0.67), indicating fair reliability.
• 2-D and 3-D reconstructed CT images demonstrated significantly higher reliability (kappa values 0.70-0.86).
• Reliability was lower for the continuous OPLL type on radiographs but improved with CT imaging.

Conclusions:

• Lateral radiography alone provides only fair reliability for OPLL classification.
• Reconstructed CT imaging (2-D and 3-D) offers good-to-excellent reliability for assessing OPLL, particularly for challenging continuous types.
• CT-based modalities are superior to lateral radiography for consistent OPLL classification by spine surgeons.