Comparative computation of orbital volume from axial and coronal CT using three-dimensional image analysis

Area of Science:

• Ophthalmology
• Radiology
• Medical Imaging

Background:

• Accurate orbital volume measurement is crucial for diagnosing and managing various orbital conditions.
• Computed tomography (CT) is a primary imaging modality for orbital assessment.
• Standardized methods for orbital volume calculation are needed to ensure consistency.

Purpose of the Study:

• To compare the accuracy of orbital volume measurements derived from axial versus coronal CT scans.
• To investigate the impact of anterior limit criteria on coronal orbital volume calculations.
• To explore novel cephalometric angles for understanding volumetric measurement discrepancies.

Main Methods:

• Thirty facial CT scans of normal orbits were analyzed using the Dextroscope image analysis program.
• Orbital volumes were calculated from both axial and coronal CT datasets.
• Coronal measurements were stratified using two anterior limit criteria (C1 and C2).
• Three novel cephalometric angular measurements of the anterior orbital aperture were computed.

Main Results:

• Orbital volume was greatest with axial scans (25.6 ± 2.4 ml), followed by coronal scans with C1 (23.8 ± 2.9 ml) and C2 (16.6 ± 2.2 ml) delimitation.
• Significant underestimation of orbital volume was observed with coronal measurements, particularly with the C2 criterion.
• Three novel angles—anterovertical, posterovertical, and horizontal orbital aperture angles—were identified and related to volume underestimation.

Conclusions:

• Coronal CT scans tend to underestimate orbital volume compared to axial scans.
• The choice of anterior limit criterion significantly influences coronal orbital volume determination.
• Novel cephalometric angle measurements may offer insights into the inaccuracies of orbital volume measurements.