Evaluation of anatomical landmark consistency in the external auditory meatus using cone-beam computed tomography (CBCT) imaging

The present study evaluated the consistency and reliability of five anatomical landmarks in the external auditory meatus using CBCT (cone beam computed tomography) scans. The goal was to determine if these landmarks could reliably replace the commonly used point Porion for superimposing CBCT scans in clinical practice. Consistent anatomical features in the external auditory meatus are essential for accurate cranial assessments in dentistry and medicine. Despite their importance, these features have been underexplored, making this study a valuable contribution to improving clinical evaluation accuracy. 22 CBCT scans were analyzed using ITK-Snap software. The shape of the External Auditory Meatus had been rendered by segmentation. These segmentations were used as a basis to locate the landmarks. The spread in location of the suggested landmarks concerning a reference coordinate system was treated as a measure for consistency. For that purpose, the absolute mean distance from all registered landmarks to the center of the location cloud was calculated for each dataset. The smallest spread in locations was measured for the so-called Epitympanic Notch, with 4.3 mm on average (SD 1.7). However, recognizing this landmark in the segmented images appeared to be relatively difficult. The landmark with the second smallest spread in locations (4.4 mm (SD 2.2)) and an easier recognition in the segmented image was the most superior point of the external auditory meatus. The most inferior point appeared to be the least reliable of all five landmarks. Based on the present study, a consistently reliable landmark in the External Auditory Meatus to replace point Porion could not be identified. The hypothesis that any landmark could suffice for superimposing CBCT scans was not confirmed. • The relationship between point Porion and the External Auditory Meatus is ambiguous. • Five landmarks may define the shape of the External Auditory Meatus. • External AuditoryMeatus landmark position with respect to the skull differs. • Alignment of CBCT scans of the human head is challenging.