Morphometric Analysis of the Anterior Clinoid Process and Its Relationship With the Internal Carotid Artery Using MDCT Angiography

The anterior clinoid process (ACP) is a critical osseous structure in skull base surgery because of its close anatomic relationship with the optic nerve and internal carotid artery (ICA). This study aimed to evaluate the morphometric characteristics of the ACP and its relationship with adjacent ICA segments using computed tomography angiography (CTA) in a Turkish population. Cranial CTA images of 200 patients (100 males and 100 females; aged 20-65 y) were retrospectively analyzed. ACP length, width, apical angle, distance to the sagittal midline, and distances to the C4 and C5 ICA segments were measured bilaterally using multiplanar reconstructions in 3D Slicer software. No significant sex differences were observed in ACP length, width, angle, or midline distance (P>0.05), except for a greater ACP-C5 ICA distance in males (P<0.05). Right-sided ACP length, width, and apical angle were significantly greater than those on the left side (P<0.05). The ACP demonstrated close proximity to the ICA, with significantly greater ACP-ICA distances on the right side for both the C4 and C5 segments (P<0.05). Mean ACP length was 13.11±2.47 mm on the right and 12.62±2.70 mm on the left, whereas mean ACP-C4 ICA distance was 1.92±1.02 mm on the right and 1.86±0.60 mm on the left. These findings demonstrate significant morphometric variability of the ACP and emphasize its close anatomic relationship with the ICA, factors that may directly influence the technical complexity and safety of anterior clinoidectomy. CTA-based preoperative evaluation may provide valuable anatomic guidance for safer surgical planning and reduction of neurovascular complications.