Morphometry of the Entire Internal Carotid Artery on CT Angiography

Background and Objectives: Knowledge of the internal carotid artery's (ICA) morphometric features is influential in outlining surgical and minimally invasive procedures in the neurovascular field. Many studies have shown divisive numbers regarding the ICA's caliber, with the measuring point of the artery sometimes differing. This study presents ICA dimensions based on computed tomography angiography in each of its seven segments as per Bouthillier's classification, correlating vascular dimensions with anthropometric parameters. Materials and Methods: A thorough CT angiography analysis was performed on 70 patients with internal carotid vessels unaffected by atherosclerotic disease. The extracranial part of the ICA was measured in four locations-carotid bulb, post-bulbar dilation, at its cervical midpoint, and below its entrance into the carotid foramen. Single landmarks were used for measurements in the intracranial segments. ICA length was assessed in the neck region and also in the cranial cavity. Craniometric measurements were performed on sagittal and coronal CT reconstructions. Patient height was taken into consideration. Results: The largest ICA portion is near its origin in the carotid sinus area (7.59 ± 1.00 mm), with a steep decline in caliber following its extracranial course. Distal ICA presented values somewhat similar to its proximal intracranial segment diameters (4.67 ± 0.47 mm). Dimensions of the ICA in the intracranial segments start from a value of 4.53 ± 0.47 mm and decrease by approximately 40% when reaching the origin of the middle cerebral artery (2.71 ± 0.37 mm), showing a marked decrease in caliber after the emergence of the most critical collateral artery, the ophthalmic branch. The length of the ICA varies between genders, with the male ICA being about 10 mm longer in total length than female ICA; this difference is also correlated with patient height and skull dimensions. Conclusions: Both intra- and extracranial ICA have variable dimensions and length related to gender and anthropometric parameters, with no significant differences obtained concerning side or age.