Clivodens Angle: A New Diagnostic Method for Basilar Invagination at Computed Tomography

Area of Science:

• Radiology
• Orthopedic Surgery
• Neurosurgery

Background:

• Craniovertebral junction anomalies, such as basilar invagination (BI), are challenging to diagnose.
• Existing craniometric methods (e.g., Chamberlain line, McGregor line) have limitations due to normal variations in anatomical landmarks.
• Computed tomography (CT) has become a primary imaging modality for evaluating these anomalies.

Purpose of the Study:

• To evaluate the efficacy of the clivodens angle (CDA) in diagnosing basilar invagination (BI).
• To compare the diagnostic performance of CDA with existing methods for craniovertebral junction assessment.

Main Methods:

• A retrospective study analyzed mid-sagittal reconstructed CT images from 63 BI patients and 100 controls.
• The clivodens angle (CDA), formed by the clivus and dens axes, was measured.
• Diagnostic performance was assessed using receiver operating characteristic (ROC) curves and interobserver reliability was evaluated.

Main Results:

• CDA measurement demonstrated good interobserver agreement (Kendall correlation coefficient = 0.891).
• BI patients exhibited a significantly smaller CDA (mean 110.4° ± 15.8°) compared to controls (mean 135.8° ± 9.2°).
• The ROC analysis yielded an area under the curve of 0.937, with a cutoff value of 125° providing the highest diagnostic accuracy (Youden index = 0.715).

Conclusions:

• The clivodens angle (CDA) is a reliable and accurate metric for diagnosing basilar invagination (BI) on CT.
• CDA demonstrates superior diagnostic performance compared to the clivoaxial angle.
• CDA offers a valuable tool for the assessment of craniovertebral junction abnormalities.